Evening Gents new to this forum. I am rebuilding a 1993 FJ1200 which had been sat for 7 years after the previous owner died. Stripped it all down and have been reassembling it and have now got to the fuel system. I have a fuel reserve switch next to the choke which plugs in to the harness. I have a stop cock on the bottom of the tank which has a single pipe which goes to the fuel pump with an inline plastic fuel filter. The fuel pump is connected to the wiring harness. I have a fuel line from the pump to the carburettors.
Can someone tell me how the fuel reserve switch works? What does it activate? Am I missing something and if so what and where should it be?
According to the Haynes manual I should have a solenoid type switch either between the tank stop cock and the fuel pump or instead of the stop cock but I have nothing and there was nothing on the bike when I stripped it down.
Any help would be appreciated. Diagrams of the set up or photos would be great.
Rob.C.
Quote from: Cass on May 11, 2017, 01:28:04 PM
Evening Gents new to this forum. I am rebuilding a 1993 FJ1200 which had been sat for 7 years after the previous owner died. Stripped it all down and have been reassembling it and have now got to the fuel system. I have a fuel reserve switch next to the choke which plugs in to the harness. I have a stop cock on the bottom of the tank which has a single pipe which goes to the fuel pump with an inline plastic fuel filter. The fuel pump is connected to the wiring harness. I have a fuel line from the pump to the carburettors.
Can someone tell me how the fuel reserve switch works? What does it activate? Am I missing something and if so what and where should it be?
According to the Haynes manual I should have a solenoid type switch either between the tank stop cock and the fuel pump or instead of the stop cock but I have nothing and there was nothing on the bike when I stripped it down.
Any help would be appreciated. Diagrams of the set up or photos would be great.
Rob.C.
The reserve switch....?
Uh Oh... the next question you can expect is what is the best oil...?! :rofl2:
:Facepalm:
edit: that isn't a very useful answer for OP, but I gave up on my reserve switch long ago, and rely only on my trip meter. Reset every fillup and get nervous above 200 miles.
The petcock on a '93 is only on or off. The line runs from the petcock, to the filter under the tank then to the fuel pump as you described.
From what I experienced on my '93, when the fuel level gets low (amount left will vary from bike to bike) the fuel pimp circuit will shut off causing you to experience what it feels like to run out of fuel. Flipping the reserve switch restores power to the pump and will allow you to run the tank to empty without further intervention. Once you activate the reserve function, fill up as soon as possible.
Quote from: Mike Ramos on May 11, 2017, 02:42:01 PM
The reserve switch....?
Uh Oh... the next question you can expect is what is the best oil...?! :rofl2:
Obviously you did not read the questions I was asking or you might have been more helpful. I asked how it worked as it is not obvious. It is quite clear from your reply that you know as little as I do about the reserve operation. Maybe oil is your speciality and you should stick to it! Thanks for your input.
Quote from: FJ_Hooligan on May 11, 2017, 03:31:42 PM
The petcock on a '93 is only on or off. The line runs from the petcock, to the filter under the tank then to the fuel pump as you described.
From what I experienced on my '93, when the fuel level gets low (amount left will vary from bike to bike) the fuel pimp circuit will shut off causing you to experience what it feels like to run out of fuel. Flipping the reserve switch restores power to the pump and will allow you to run the tank to empty without further intervention. Once you activate the reserve function, fill up as soon as possible.
Thank you FJ Hooligan that explains a lot. It was not very clear looking at what I had on the bike how it worked and I did not have a operators manual come with the bike. Thanks for your prompt and informative reply.
Quote from: Cass on May 11, 2017, 04:50:00 PM
Quote from: Mike Ramos on May 11, 2017, 02:42:01 PM
The reserve switch....?
Uh Oh... the next question you can expect is what is the best oil...?! :rofl2:
Obviously you did not read the questions I was asking or you might have been more helpful. I asked how it worked as it is not obvious. It is quite clear from your reply that you know as little as I do about the reserve operation. Maybe oil is your speciality and you should stick to it! Thanks for your input.
Nah, it's kind of an inside thing on this forum about the reserve switch. There's been years of debate on how it works, what it does and such. Literally years and probably thousands of posts on it. Kind of a hot topic with as many opinions as....well, which oil is best to use.
You just had the misfortune to stumble into it, not knowing the history. Kind of like running around a corner and going face first into a hornets nest you didn't know was hanging there....... :crazy:
But, it is an on/off thing. The bike will start to "stutter/miss/etc" once the fuel level reaches a certain point.
The debate is on what the switch actually does, since it's not a traditional style petcock where there is a stand tube inside the tank. Some say it cuts ignition, some say it turns off the fuel pump, some think it's the pull of the moon on the fuel level in the bowls.........(I kid).
I personally, do as an above poster, as I have with all my bikes through the years: set the trip, start looking for fuel up when I know I'm getting close. If it starts to sputter, walking is imminent (in my mind at least). Toss the RES switch and hope it has enough for you to find the next gas stop.
I also don't particularly trust the "electronic res" switch on the FJ. Sure, it works, but I don't have the confidence in it reading the fuel level as I do with a stand pipe petcock where I absolutely
know beyond a shadow of a doubt there's so many gallons left when it starts to sputter.....
;)
I thought that was put to bed several years ago....the reserve switch re-activates the fuel pump...period.
You can hear it clearly.
Quote from: Cass on May 11, 2017, 04:50:00 PM
Quote from: Mike Ramos on May 11, 2017, 02:42:01 PM
The reserve switch....?
Uh Oh... the next question you can expect is what is the best oil...?! :rofl2:
Obviously you did not read the questions...
Oh, he read it...
It has been cover at length with, arguably, no clear understanding.
Reserve Switch (http://www.fjowners.com/index.php?topic=9996.msg99506#msg99506)
Randy - RPM
Quote from: Pat Conlon on May 11, 2017, 05:24:59 PM
I thought that was put to bed several years ago....the reserve switch re-activates the fuel pump...period.
Pat, after looking at the circuit many more times I am still not convinced or been shown the that the fuel pump is shut of...period.
Unless there is a turbo fill function like Harvy said way back then...
Look at #3 of the operation in the schematic below...
"Determining timing for switch on ignition coil (duty cycle)"
(http://i1215.photobucket.com/albums/cc517/racerrad8/fuelpump001_zpsb2265a3f.jpg~original) (http://s1215.photobucket.com/user/racerrad8/media/fuelpump001_zpsb2265a3f.jpg.html)
And then, I do not see the "reserve switch" listed, shown or mentioned in the "fuel pump circuit" below.
(http://i1215.photobucket.com/albums/cc517/racerrad8/FuelPumpCircuit001_zps98e8bd01.jpg~original) (http://s1215.photobucket.com/user/racerrad8/media/FuelPumpCircuit001_zps98e8bd01.jpg.html)
I still stick with my theory of the CDI receiving the low fuel reading from the sender. It then changes the duty cycle of the coil drivers. The bike then misfires, but not so much it would affect the performance. Once the "reserve" switch is toggled, the proper duty cycle is then re-activated and the bike runs at full song.
If not, please, please, please explain to me how the bike instantly comes back to proper running/full power without having a delay of refilling the fuel bowls since the fuel pump has been turned off and the fuel bowls are running dry.
Randy - RPM
Quote from: Cass on May 11, 2017, 04:50:00 PM
Quote from: Mike Ramos on May 11, 2017, 02:42:01 PM
The reserve switch....?
Uh Oh... the next question you can expect is what is the best oil...?! :rofl2:
Obviously you did not read the questions I was asking or you might have been more helpful. I asked how it worked as it is not obvious. It is quite clear from your reply that you know as little as I do about the reserve operation. Maybe oil is your speciality and you should stick to it! Thanks for your input.
Hold on a minute... obviously you did not read the series of posts from several years ago or you might have been a little less.... Oh forget it!
Hey Cass, lighten up, sometimes just having a bit of fun is the way to go - so let's not get too serious; laughter is the best medicine...!
[The serious thing is to always] Ride Safe,
Midget
It's quite easy to find out for your self:
Run the bike until it stumbles and the engine dies. Clutch in, pull over to the side of the road. Take your helmet off and ear plugs out so you can hear. Now turn the key off, and then on. Do you hear the fuel pump? The usual 3-5 second chatter ((before it times out) when you turn the key on? No, you don't.
Wait! You say you don't hear the fuel pump because the bowls are full....
Here's the kicker:
Now turn the reserve switch to reserve and turn the key on.
You will now hear the fuel pump chattering away.
If it was ignition interrupt I would expect to hear a pop or backfire from igniting all the accumulated unburned fuel. The same sound you get from today's quick shifters which use ignition interrupt.
You will say, but it's a soft stumble, Ok, that would prevent that, but, tell me.
If it were set as an ignition interrupt why does it get progressively worse?
To a point where the engine dies. Why can't you just limp along with the stumble? Why kill the engine?
Like I said: It's easy to find out yourself (just don't do it on the freeway)
OK, next time I run out of gas I'll check it out. But not something I think will happen anytime soon.
As far as your backfire theory.
I did not say shut the ignition off which will then flood the cylinder with unburned fuel. Then once spark is introduced a backfire occurs due to the unburned fuel in the exhaust pipes.
I am saying reduced duty cycle causing misfire.
Now, the explanation on how the engine comes back to life instantly with the flip of the reserve switch. I previously posted a video of your bike stumbling as the carbs refill.
I did this with your bike to make sure there was no question about the electrical reserve system. Your bike does not have it.
So, what is your take on the instantaneous change with the flip of the switch, what happens?
Randy - RPM
Sorry Randy, I was modifying my post when you responded...
My '84 doesn't have that silly reserve system. It's a big boys bike. No nanny here.
My theory is that for the bike to start to stumble, the fuel level in the bowls just has to be a *tiny* bit low at the pilots.
The rider flips the reserve switch before the fuel level gets too low, and the pump cycles back on and "quickly"
brings the fuel level back up to the level of the pilot jets.
We are not talking about the time it takes to fill up an empty bowl, nothing like that.
Just the time it takes add a millimeter (or two) of fuel to the bowls.
A few questions based on your theory.
1) So, there is a "quick fill" function of the fuel pump.
How does that work?
Regulated voltage to the pump?
2) Are you implying the pilot jet circuit is still in play at 60 mph?
If that is not the case, how does the engine start to sputter when the pilot circuit is not in use?
3) finally, since the only function is the fuel pump being shut down how do you explain the function of the 86-87 reserve system.
There is no "quick fill" option there. So how does the gravity feed system quickly refill the carbs?
Randy - RPM
Seems to me a simple experiment could sort it out.
Drain the tank, set up a gravity feed like what I use for carb synch. Simulate the fuel sender showing empty with the RES off (ie normal position).
If the bike stumbles on a straight gravity feed and the gauge showing empty (or near it) it would seem the bike is pulling ignition. If it keeps chugging right along, then it's manipulating the fuel pump.
Would be easy enough when doing a carb sync to perform that simple little test.
I might check it out myself when I do my 4 gas and carb balance for this season....more for the sake of my own curiosity as anything else....
My response is in green
A few questions based on your theory.
1) So, there is a "quick fill" function of the fuel pump.
How does that work?
Regulated voltage to the pump?
No, just the regular fill rate
2) Are you implying the pilot jet circuit is still in play at 60 mph?
Sure, Speed has nothing to do with it, throttle position does. At 1/4 throttle opening the pilots are flowing. When a rider runs out of fuel the bike starts to stumble. The rider naturally opens the throttle further and the bike momentarily recovers as it draws fuel from the mains (feeding the needle jets) this continues until the fuel level in the bowls drop below the level of the mains, then the engine stalls.
If that is not the case, how does the engine start to sputter when the pilot circuit is not in use?
3) finally, since the only function is the fuel pump being shut down how do you explain the function of the 86-87 reserve system.
My experience (that supports my theory) is with the fuel pump FJ's. I do not have, or ever had an '86/87 FJ so I can only guess...Ok so we are back to the non fuel pump '86/87 with a reserve switch. Obviously not a fuel pump interrupt.
***Tell me the purpose of the wires going to the petcock on the '86/87?***
Ignition interrupt? Not likely.
I would like to experiment with a '86/87 petcock, see what happens to the flow
Quote from: great white on May 11, 2017, 09:37:20 PM
Seems to me a simple experiment could sort it out.
Drain the tank, set up a gravity feed like what I use for carb synch. Simulate the fuel sender showing empty with the RES off (ie normal position).
If the bike stumbles on a straight gravity feed and the gauge showing empty (or near it) it would seem the bike is pulling ignition. If it keeps chugging right along, then it's manipulating the fuel pump.
Would be easy enough when doing a carb sync to perform that simple little test.
I might check it out myself when I do my 4 gas and carb balance for this season....more for the sake of my own curiosity as anything else....
Good idea :good2: Certainly safer than what I went through.....
Gentlemen,
In response to Great White here is something along the lines you suggest - but in actual riding. It may not be conclusive and I do not claim it is, however it is based on repeated experiences... [I trust dear Mr. Cass is not offended...] Anyways, below is from a post from September, 2013...! Keep smiling...
"Howdy everyone,
Well, while Mr. Conlon's statement implies the fuel pump is involved in the operation of the reserve switch it does not disprove that the CDI unit is not canceling out the ignition as well.
If I may state my experience, which while it may not be conclusive to this discussion, it may have some merit.
I have an auxiliary fuel tank that I have plumbed through a fuel transfer valve which in turn leads to the fuel pump.
As I run the auxiliary tank dry, without involving the CDI unit or fuel pump shut off in any way, the engine stumbles and misses, prompting me to transfer to the main tank and there is a delay before the engine is up and running again.
Now, running on the main tank as I go on reserve the engine again begins to miss but it seems to be just that, an engine misfiring, not running out of fuel, AND it is noticeably different from when the auxiliary tank runs dry. And when switched to the reserve (on the main tank) and the engine resumes its' normal cadence, it is noticeably different and quicker than when the engine has actually run out of fuel.
So for what it is worth, that is my experience with the reserve switch...."
I am glad I have an 86 .
with all this information on the fuel pump models cutting out the ign. I thought this was solved years ago and somebody figured out it just cuts 1 of the coils and runs on the other till you click onto reserve. Basically running on 2 cylinders .
I am so sorry for opening this can of worms and so glad that I put that I was new to the forum at the beginning of my question.
Not being aware of the previous history of this subject I apologies to Mr Ramos for being short with him.
Having said that I did try and search the forum on details of the reserve switch but came up blank so I blame the forum search engine for not being any good.
Thanks for all your replies and I will keep an eye on the trip rather than rely on the switch.
yeah , just like the old days before fuel guages on bikes... wow how spoiled we are now.
I remember just opening the gas cap and looking in as you rock the bike side to side and telling your buddies " ya , I can go another 50 miles".
Final note from me on the fuel reserve is that it works on the FM electrical principal ... Fuck'in Magic .
In my opinion,with a few notable exceptions, this has been a very informative, educational thread on the reserve switch. Lots of knowledgeable exchange of opinions and theory's. There is apparently still a lot of meat left on this bone. Maybe it is time for another oil thread. :drinks:
Oh Jesus... this again? :flag_of_truce:
edit: never mind... I remember Randy was right.
Quote from: Mark Olson on May 12, 2017, 02:57:31 AM
it works on the FM electrical principal ... Fuck'in Magic .
Ha... and the magic smoke got out of mine I guess since it doesn't work at all.
I've never bothered to figure out why, but Wiz only runs the fuel pump with the switch in reserve. If you switch to normal, it also runs fine until the fuel bowls start to run dry and then it sputters and gets worse until it dies. Switching back to reserve quickly, but not immediately fixes the problem as the bowls refill... this supports the thought it just interrupts fuel pump power when low fuel light comes on (Wiz was ABS, so it has no low fuel light).
My $0.02...
Frank
What a way to welcome in the weekend with the resurfacing of this old chestnut.
Let me make it very clear. How the reserve switch functions is not and never has been in doubt. The only issue has ever been who understands it and who doesn't.
How do you like your proof served up...
Anecdotal
professional
Empirical
Scientific
It has been proven every which way.
FFS, this is kindergarten level diagnostics. I know this is an owner's forum and not a mechanic's forum but proving it for yourself for those who have even basic mechanical knowledge is simple. This idea that it is an ongoing mystery is absolute rubbish.
Some years back when this was discussed at length, I conducted some tests, not for my benefit but to demonstrate beyond doubt how it worked. The results were irrefutable, until Randy called into doubt my professional credentials and suggested that my findings were not credible unless supported by video. Errr, that would be a video showing a test light on......then off......then on...... The suggestion that I couldn't tell the difference or that I was misrepresenting the facts beggars belief.
Rich Pleinnes- there is no meat left on the bone. This is not the space shuttle, it is the reserve switch on a motorbike. Figuring out how it worked was instant, proving it took 5 mins (and has been previously posted)
Mark Olsen - the symptoms of electrical vs fuel interuption cannot be mistaken one for the other. Especially a bike cutting to 2 cylinders as opposed to running out of fuel. There is a chasm between the two. The idea you mention that it cuts to 2 cylinders was not the resolution but the myth that was dispelled. I see no point in being glad you don't have a fuel pump, it is the only way to get proper filtration and in use, are trouble free. Petcocks seem to give far more grief here than pumps.
Mike Ramos - I don't know where your reserve fuel tank is but presumably it is further away from the pump than the bike tank. Of course it's going to take longer to draw fuel from it. The time it takes is relative to the distance it has to travel and the amount of fuel it has to move).
Great White - the test has been done a number of ways. The simplest one being putting a test light on the pump when the main tank starts to splutter. Tip the bike to left so that what little fuel remains flows away from the sender unit and the light goes out. Stand the bike upright (or to the right} it comes back on. With it tilted to the left and the test light off, move the switch to "RES" and the light will instantly come on. Or, as Pat described, simply pull over when the bike stops running on the main tank, with the ignition on and switch to RES and you can hear the pump spring into action.
Randy - there is no "quick fill" function and there is no relevance to earlier non fuel pump models. The restoration of normal power is NOT instant when you flick the switch, it takes a number of seconds to regain normal operation. The time depends of the how long you have let it stumble before switching it over. If you are tuned into your bike and pick it up at the very subtle onset, it is very quick, it you wait until the thing will barely run, it takes longer after switching over (more fuel needed to fill the bowls) As for the manual not mentioning the switch in the circuit, as you know, workshop manuals have many errors and omissions. However, what you have in front in you is what it is.
Pat Conlon - you are right, it starts out so subtly you can barely pick it and gets progressively worse until it eventually dies, switching to reserve if left until this stage takes longer to restore power.
Randy (again) much of you argument seems to stem from the belief that power is restored "instantly" when switched to reserve, it's not. The longer you leave it stumbling before switching over, the longer it takes to run clean again.
I don't know whether you ride this model yourself and if so how often you run it to reserve, but the restoration of power is definitely not instant.
Zoa - maybe you could contribute your own findings on this subject.
Frank - makes sense.
The bottom line is, there is no mistaking an engine running out of fuel with one that is running out of spark.
Great stuff guys, just like the old days!
IMO
Noel
I hope you undestand my bad english : reserve switch work that vay (AND IT VORKS OPPOSITE WAY BY SWITCH) , first cut off 2 cylinder (one coil) then bike run rough, if contininue driving pump cut fuel fuel supply(all in cdi brains)
as you parked bike abouth 5min reseve switch reset (cdi) and you can drive abouth 3-5 miles, then it will do it again IT was pain in ass to find
problem aboth 1000 dollars for pieces, hope no one dont have to fix 1dollar problem that way) now days dont use that switch bypassed by cdi and prefer gauge and tank .
yours SEPPO
Good morning fellas (notice I did not say Gentlemen; wanted to include everybody!).
Holy Toledo!
Noel, nice to see you so inclusive! I think you covered almost everyone & some more than once!
Speaking only for myself, it is not the distance the fuel travels but the symptoms observed over several years, many a mile & repetitions. That being said, I make NO definitive claim other than it is merely an OBSERVATION.
Mr. Cass – no apologies necessary as it is all in good fun – actually that word cannot be found on this Forum so let's "blame the useless search engine for not being any good"... in fact how can you be "short" with someone who is a Midget...?!
Uh oh... Now I see Reply #26... a possible refutation of the test which are (were?) irrefutable... Noel, you may not believe this coming from me but I hope you are not (once again) going away...
Oh my, never thought I would see the day where it may be better to discuss oil – would the gentleman from southern California like to begin...?!
Keep smiling!!!
And of course ride safe,
Midget
EDIT: Mr. T: just kidding
Once again this topic will just go away with no true, factual supported resolution; although it was again a nice debate. But there are questions that cannot and have not been answered.
I give up, :flag_of_truce: I concede :flag_of_truce: and you guys can run with your synopsis.
Quote from: Pat Conlon on May 11, 2017, 05:24:59 PM
I thought that was put to bed several years ago....the reserve switch re-activates the fuel pump...period.
Quote from: ribbert on September 26, 2013, 06:28:04 PM
I don't know why everyone's making such a meal of this, it's simple enough to check, and I just have.
My bike happens to only have a cupful of fuel in it and has been on reserve for a few days.
I just started it on the side stand, switched it back to main, waited for it to splutter, probed the live wire to the pump, nothing. While holding the test light on the terminal, switched to reserve, light immediately comes on, power restored to pump.
Repeat cycle 3 times, same results.
Noel
Quote from: RichBaker on September 26, 2013, 07:25:46 PM
ETA: Looks like Noel just proved it's a FUEL-cut, not spark, for the pump-equipped models...
Someday someone, somewhere will actually have to apply a little more diagnosis and research and present the facts. But until then
kindergarten diagnostics and
personal interpretation/observations will have to suffice.
Man, I wish it was the weekend here, Friday has just begun.
I have a rally to work on, I'm out of this one for now...
Randy - RPM
I have a tank that is empty. I will pull the fuel sending unit out and investigate and see if I can get some definitive information this weekend.
Fred
Quote from: racerrad8 on May 12, 2017, 10:40:00 AM
Someday someone, somewhere will actually have to apply a little more diagnosis and research and present the facts.
We can make this a WCR project... Wiz always needs to be in Res to run the fuel pump, so we know the pump's not getting power in Normal. All we have to test is whether I'm getting a low signal from my fuel level sensor. If I am, then switching to Normal position should induce a miss instantly if there is any ignition impact from the low fuel signal... I know it doesn't do that (we'll confirm that as well however), so we would have definitive proof for a '92 ABS model at least.
Frank
Re: Speed Hut Multi Gauge install
« Reply #27 on: March 30, 2017, 10:32:45 AM »
Reply with quoteReply with Quote Modify messageModify Remove messageRemove Split TopicSplit Topic
The only negative that I can take away from this project reared it's head this morning. This revolves around the reserve switch circuit. With the switch in the on position, there is no power to the fuel relay. Put the switch in the reserve position and the fuel pump is happily clicking away. At the moment I am not that concerned. The new fuel gauge has a low fuel warning light and I plan to monitor the fuel situation as the tank gets near the empty mark.
I pulled this from my aftermarket gauge install for the 1989 1300. Just like the Wizard, I am required to have the reserve switch activated for the fuel pump to work. I have not investigated the whys for this to be the case.
The empty fuel tank and the fuel sender that I will look at this weekend is on my 1990 1200 that has all OEM wiring and gauges. I am hopeful that I can submit some good answers. I think it will help, that I am an Electrician by trade.
Fred
Quote from: Mike Ramos on May 12, 2017, 10:18:07 AM
Good morning fellas (notice I did not say Gentlemen; wanted to include everybody!).
Holy Toledo!
<snip>
Oh my, never thought I would see the day where it may be better to discuss oil – would the gentleman from southern California like to begin...?!
Keep smiling!!!
And of course ride safe,
Midget
EDIT: Mr. T: just kidding
I'll take my cue:
AmsOil (http://www.fjowners.com/index.php?topic=80.0) is the only way to go!. If you use anything else you might as well run Harley oil! :diablo:
Ed
Quote from: ribbert on May 12, 2017, 09:29:02 AM
What a way to welcome in the weekend with the resurfacing of this old chestnut.
Let me make it very clear. How the reserve switch functions is not and never has been in doubt. The only issue has ever been who understands it and who doesn't.
How do you like your proof served up...
Anecdotal
professional
Empirical
Scientific
It has been proven every which way.
FFS, this is kindergarten level diagnostics. I know this is an owner's forum and not a mechanic's forum but proving it for yourself for those who have even basic mechanical knowledge is simple. This idea that it is an ongoing mystery is absolute rubbish.
Some years back when this was discussed at length, I conducted some tests, not for my benefit but to demonstrate beyond doubt how it worked. The results were irrefutable, until Randy called into doubt my professional credentials and suggested that my findings were not credible unless supported by video. Errr, that would be a video showing a test light on......then off......then on...... The suggestion that I couldn't tell the difference or that I was misrepresenting the facts beggars belief.
Rich Pleinnes- there is no meat left on the bone. This is not the space shuttle, it is the reserve switch on a motorbike. Figuring out how it worked was instant, proving it took 5 mins (and has been previously posted)
Mark Olsen - the symptoms of electrical vs fuel interuption cannot be mistaken one for the other. Especially a bike cutting to 2 cylinders as opposed to running out of fuel. There is a chasm between the two. The idea you mention that it cuts to 2 cylinders was not the resolution but the myth that was dispelled. I see no point in being glad you don't have a fuel pump, it is the only way to get proper filtration and in use, are trouble free. Petcocks seem to give far more grief here than pumps.
Mike Ramos - I don't know where your reserve fuel tank is but presumably it is further away from the pump than the bike tank. Of course it's going to take longer to draw fuel from it. The time it takes is relative to the distance it has to travel and the amount of fuel it has to move).
Great White - the test has been done a number of ways. The simplest one being putting a test light on the pump when the main tank starts to splutter. Tip the bike to left so that what little fuel remains flows away from the sender unit and the light goes out. Stand the bike upright (or to the right} it comes back on. With it tilted to the left and the test light off, move the switch to "RES" and the light will instantly come on. Or, as Pat described, simply pull over when the bike stops running on the main tank, with the ignition on and switch to RES and you can hear the pump spring into action.
Randy - there is no "quick fill" function and there is no relevance to earlier non fuel pump models. The restoration of normal power is NOT instant when you flick the switch, it takes a number of seconds to regain normal operation. The time depends of the how long you have let it stumble before switching it over. If you are tuned into your bike and pick it up at the very subtle onset, it is very quick, it you wait until the thing will barely run, it takes longer after switching over (more fuel needed to fill the bowls) As for the manual not mentioning the switch in the circuit, as you know, workshop manuals have many errors and omissions. However, what you have in front in you is what it is.
Pat Conlon - you are right, it starts out so subtly you can barely pick it and gets progressively worse until it eventually dies, switching to reserve if left until this stage takes longer to restore power.
Randy (again) much of you argument seems to stem from the belief that power is restored "instantly" when switched to reserve, it's not. The longer you leave it stumbling before switching over, the longer it takes to run clean again.
I don't know whether you ride this model yourself and if so how often you run it to reserve, but the restoration of power is definitely not instant.
Zoa - maybe you could contribute your own findings on this subject.
Frank - makes sense.
The bottom line is, there is no mistaking an engine running out of fuel with one that is running out of spark.
Great stuff guys, just like the old days!
IMO
Noel
Ugh... as an electronics technician trained in TTL logic, I understand the function of a digital system and the use of square wave duty cycle to modulate fuel delivery, therefore, it makes sense that the fuel sensor that is fed to the digital computer is doing precisely that - varying the duty cycle of the ignition, not turning off the fuel pump, which in turn reduces the flow of fuel (modulates pressure), while not simply draining the bowls empty. This is why both theories have some validity.
There.
I'm confused. How does varying the duty cycle of the ignition reduce fuel flow?
Those appear to be totally different and unrelated outputs of the Digital Ignitor Unit.
Quote from: aviationfred on May 12, 2017, 11:52:05 AM
Re: Speed Hut Multi Gauge install
« Reply #27 on: March 30, 2017, 10:32:45 AM »
Reply with quoteReply with Quote Modify messageModify Remove messageRemove Split TopicSplit Topic
The only negative that I can take away from this project reared it's head this morning. This revolves around the reserve switch circuit. With the switch in the on position, there is no power to the fuel relay. Put the switch in the reserve position and the fuel pump is happily clicking away. At the moment I am not that concerned. The new fuel gauge has a low fuel warning light and I plan to monitor the fuel situation as the tank gets near the empty mark.
I pulled this from my aftermarket gauge install for the 1989 1300. Just like the Wizard, I am required to have the reserve switch activated for the fuel pump to work. I have not investigated the whys for this to be the case.
The empty fuel tank and the fuel sender that I will look at this weekend is on my 1990 1200 that has all OEM wiring and gauges. I am hopeful that I can submit some good answers. I think it will help, that I am an Electrician by trade.
Fred
I think I can explain this based on the first diagram that Randy posted.
On the upper left, what is called the Fuel "Censor" (A) appears to be a variable resistor to ground. Part of this circuit includes the Fuel Warning Light (B). Current flows through the light on its way to ground through the Fuel Sensor. I would assume that the Fuel Sensor has high resistance when the tank is full and gets progressively less restrictive as the tank empties. The Digital Ignitor Unit (H) sees the fuel level as a signal that's proportional to the amount of current flowing through the Fuel Sensor via the Fuel Sensor Input Circuit (I) which converts the analog signal into something digital that the CPU uses.
As the resistance decreases and the current flow through this part of the circuit increases it begins to light up the Fuel Warning Light. The light gets brighter as the fuel level goes down. The Fuel Level Input Signal is evidently an input to the CPU which activates the Fuel Pump Relay (T) and keeps the pump running. At some point, the "fuel" signal exceeds a threshold current level and the CPU shuts off the fuel pump relay.
The Reserve Switch (D) provides an input to the CPU that provides bypass logic that turns the fuel pump relay (back) on.
If you need to have the reserve switch on all the time then that means you've lost the leg of the circuit that includes the Fuel Warning Light and the input signal to the Fuel Sensor Input Circuit. Does your fuel gage work? I would think this signal is a derivative of what drives the fuel gage.
DavidR.
Studying the wiring diagram, the fuel gage level is a separate signal from the tank sender unit. It's a green wire.
The input to the Relay Assembly and the Fuel Pump Relay that also runs to the Fuel Warning Light is G/R (green/red).
See if you can ohm the G/R wire from the tank sensor connector to the Relay Assembly connector. If you don't have continuity, that would be a good place to start. I don't think the circuit grounds through the Fuel Warning Light (although that's a remote possibility, meaning that if the bulb is not in place then the circuit is dead but that would be a really dumb circuit design)
Noel,
no fuel pump to go bad , I have a larger hose to fill my bowls.....
larger needle and seat that don't plug up , and living in California my fuel is good.
So yeah ,, I'm Glad.
As for the Reserve switch quest , it appears the fuel relay power is cut ...and what else? maybe it reduces power to conserve fuel to get you to the next gas station. An off the road stationary test is invalid.
Please conduct the following test for the good of the FJ collective.
attach sensors and probes to your ignition system to record input and out put voltages while operating your FJ.
now ride till you run out of gas and have to switch to reserve but don't switch till the engine dies and you can record your readings ... Like does the engine still get spark when you have stalled with the reserve switch still off.
Make sure you ride to a remote area as roadside tests are dangerous ..
I am counting on you.
Quote from: Mark Olson on May 13, 2017, 03:15:16 AM
Noel,
no fuel pump to go bad , I have a larger hose to fill my bowls.....
larger needle and seat that don't plug up , and living in California my fuel is good.
So yeah ,, I'm Glad.
As for the Reserve switch quest , it appears the fuel relay power is cut ...and what else? maybe it reduces power to conserve fuel to get you to the next gas station. An off the road stationary test is invalid.
Please conduct the following test for the good of the FJ collective.
attach sensors and probes to your ignition system to record input and out put voltages while operating your FJ.
now ride till you run out of gas and have to switch to reserve but don't switch till the engine dies and you can record your readings ... Like does the engine still get spark when you have stalled with the reserve switch still off.
Make sure you ride to a remote area as roadside tests are dangerous ..
I am counting on you.
Yeah, sure Mark. as soon as I finish the parabolic algorithms for re entry I'm working on I'll move onto the serious stuff. :biggrin:
Mark, I don't have a handle on your sense of humour and I don't want to offend you but I will go with my gut feel and assume your suggestions are tongue in cheek.
On the off chance you are being serious......
Why is an "off road stationary test" invalid. How does forward speed effect such a test?
You agree power is cut to the fuel pump. Why would you then have reduced spark as well if there is no fuel to ignite?
There is one point that many seem to overlook, it is just a fuel reserve function on a garden variety bike. Just how complicated were Yamaha going to make it?
I say again, there is no mistaking a bike running out of fuel with one running out of spark.
As for the bigger needle and seat (which really isn't that much bigger and the bigger hose which is irrelevent), they just let bigger crap through.
The benefit from the filter the pump allows you to run is less crap in your carbies. A fuel pump should only need replacing once in the entire life of your bike, hardly a biggy.
You are lucky to live somewhere with good fuel. We are also lucky here in that regard.
IMO
Noel
If you don't charge the coil up to its rated voltage then the spark is weak(er). Just how much spark does it take to ignite an air/fuel mixture?
If you cut the spark completely you run the risk of fouling a plug.
I don't think either of those options are a logical design approach for a running out of fuel simulation.
Quote from: ZOA NOM on May 12, 2017, 04:31:35 PM
Ugh... as an electronics technician trained in TTL logic, I understand the function of a digital system and the use of square wave duty cycle to modulate fuel delivery, therefore, it makes sense that the fuel sensor that is fed to the digital computer is doing precisely that - varying the duty cycle of the ignition, not turning off the fuel pump, which in turn reduces the flow of fuel (modulates pressure), while not simply draining the bowls empty. This is why both theories have some validity.
There.
Rick, thanks for responding but you're attributing way too much complication to such a simple task and have ignored one very basic feature, the fuel pump DOES turn off when low on fuel, it has no power until the reserve switch is activated or fuel added. Without fuel it doesn't matter what the spark is doing, there's nothing for it to ignite.
This was a first generation step up from manual petcocks 25 years ago on a bike with a crude electronic engine management system, not an F18.
A fuel reserve function on bikes is a hangover from when they didn't have fuel gauges, not emerging technology. When was the last time you owned a car with a reserve switch? The last one I owned was a 1951 Rover.
Rick, run your bike dry on the main tank and put a test light or multi meter on the fuel pump, there will be no power. Switch to reserve and power will be restored, it's that simple.
Noel
Quote from: Mike Ramos on May 12, 2017, 10:18:07 AM
Noel, nice to see you so inclusive! I think you covered almost everyone & some more than once!
Can't have anyone thinking their contributions are not valued and worthy of a response.
Noel
Quote from: Mike Ramos on May 12, 2017, 10:18:07 AM
... Noel, you may not believe this coming from me but I hope you are not (once again) going away...
Midget
Mike I agree with you, I don't.
Noel
I think that there are more variables at play here with the engine "Simply running out of fuel", that may make it seem like it is losing spark energy in a couple cylinders.
Although I have absolutely No DATA on whether it cuts spark or not, I HAVE run my tank down to the point where I've had to switch it to "RESERVE" to keep going........
In each of these instances, I've noticed a very slight hiccup in the engine running. At which time I instinctively twist the throttle a little further, and that seems to clear the hiccup as well as restore forward acceleration for just a moment. If I keep riding, the hiccups gradually become more frequent, and the engine starts to run worse and worse until the point it quits.
If I catch it while the engine is still running, and switch the RESERVE switch, it does take a few seconds to restore normal-smooth engine running with no hiccups.
Each of these times that I have experienced, the transition back to smooth running was not "Instant" like it would be if Spark was suddenly restored. It has always taken a few seconds.......
This would support Pat's theory on fuel dipping to just below the pilot jet, to cause a stumble under part-throttle conditions............And when you instinctively give it more throttle, more fuel flows through the main and the engine will "Un-stumble"
I've ridden bikes with clogged pilots. They won't idle, they spit and stumble at part-throttle, but will pull all day at WOT.
But how does this explain why (at first) when running out of fuel, it only seems to stumble on one or two cylinders?
In my opinion, try as you might (especially with a higher mileage engine) you will never get all of the cylinders exactly balanced.............
There are so many variables to this: Valve clearances, piston ring sealing, valve stem sealing, variances in the amount of carbon in each cylinder, compression in each cylinder, temperature of each individual cylinder, variances in the carb bodies themselves, etc.............
You can sync the carbs to get them as close as you can, and you can try to get the floats all even or the fuel bowl levels as even as possible, but you will never get them "EXACT"
While the engine is running, there will always be some cylinders that draw a bit more air than the others, or that use a bit more fuel than the others...............You would never notice this while the engine is running, and the fuel pump is constantly keeping the fuel bowls topped up...
But once you cut the fuel pump, and the re-supply to the fuel bowls stops, there will always be one or two cylinders that run out first and start to stumble.
It is not as straightforward as instantly cutting all the fuel to the engine at once........
If you are really keen on how your bike is running, and catch it right away and hit the RESERVE switch, the 2 or 3 cylinders that are still running properly will continue to do so until the cylinder that was stumbling is re-supplied with fuel.
If you continue to ride and do nothing, the rest of the cylinders will all eventually drop out and stumble, until the engine just will not run anymore..
This is exactly what I experienced the few times that I have run the tank down to require "RESERVE".
Anyway, I'm sure this debate will continue in the future until someone comes up with some "Hard Data" on the cut-fuel/cut-spark debate, and I have absolutely NO DATA on the spark side of it.
I simply have my doubts that the engineers at Yamaha would have made the RESERVE function more complicated than simply "Cutting the power to the Fuel Pump", but I could be wrong. There are some crazy engineering stories in the world of Motor-Driven Vehicles............. :drinks:
Quote from: ribbert on May 13, 2017, 09:53:47 AM
Quote from: ZOA NOM on May 12, 2017, 04:31:35 PM
Ugh... as an electronics technician trained in TTL logic, I understand the function of a digital system and the use of square wave duty cycle to modulate fuel delivery, therefore, it makes sense that the fuel sensor that is fed to the digital computer is doing precisely that - varying the duty cycle of the ignition, not turning off the fuel pump, which in turn reduces the flow of fuel (modulates pressure), while not simply draining the bowls empty. This is why both theories have some validity.
There.
Rick, thanks for responding but you're attributing way too much complication to such a simple task and have ignored one very basic feature, the fuel pump DOES turn off when low on fuel, it has no power until the reserve switch is activated or fuel added. Without fuel it doesn't matter what the spark is doing, there's nothing for it to ignite.
This was a first generation step up from manual petcocks 25 years ago on a bike with a crude electronic engine management system, not an F18.
A fuel reserve function on bikes is a hangover from when they didn't have fuel gauges, not emerging technology. When was the last time you owned a car with a reserve switch? The last one I owned was a 1951 Rover.
Rick, run your bike dry on the main tank and put a test light or multi meter on the fuel pump, there will be no power. Switch to reserve and power will be restored, it's that simple.
Noel
Noel,
If it was simply a cutout for power to the fuel pump, it wouldn't need to go through the CPU. Just wire a power lead to the pump and move on. It goes through the CPU because it does more than simply restore 12v to the fuel pump. I believe it does both simultaneously - changes the duty cycle of the ignition to give the feeling of a miss, and reduces the fuel pressure so the pump doesn't force fuel when the timing is off.
Look at items P,Q & R on the diagram. They are all connected to a transformer with 12v supplied to the other side from the main switch. The CPU will modulate the current flow through each transformer (all four ignition coils for timing and the fuel pump relay for pressure), by varying the duty cycle of the waveform applied.
PS - An F-18 is 1990's technology. Now if you had said YF-22... :good2:
A couple of years ago heading to the annual Mapleton Muster I noticed the bike was down a little bit on power nearing the top of the range but wasn't too concerned as i had a passenger on and the bike still seemed to be running ok, so headed to the servo to top up on fuel for the days ride. As I was pulling in i noticed it started to run on three cylinders, gave it a couple of revs, same thing so assumed a spark plug must've packed it in but decided to check it out after breakfast. Asked a couple of people at the cafe if they had a plug spanner because that's the symptom it was giving.
After breakfast started it again and it got progressively worse running from three cylinders then two cylinders until it finally stopped. It was then I noticed the pump was clicking like mad and no matter how many times the key was turned on and off it just wouldn't build up pressure, so deemed it the culprit. Pulled the inlet hose off the pump and hooked it straight to the carbs and it fired straight up and ran like a train for the rest of the day.
I've been fiddling around with bikes and cars since I was a teenager so have a little knowledge on how things work and can trouble shoot some problems, but in this case what gave the impression to me it was spark related turned out being a fuel problem, so maybe that's what other people feel when riding and are thinking as well.
I can't see the reserve function being too complicated on the fuel pump models where the manufactures went to the extra effort to design it where it affects both spark and fuel. The early models got away with simple petcocks, why over complicate things with the pump models.
Quote from: ZOA NOM on May 13, 2017, 01:59:52 PM
If it was simply a cutout for power to the fuel pump, it wouldn't need to go through the CPU. Just wire a power lead to the pump and move on. It goes through the CPU because it does more than simply restore 12v to the fuel pump. I believe it does both simultaneously - changes the duty cycle of the ignition to give the feeling of a miss, and reduces the fuel pressure so the pump doesn't force fuel when the timing is off.
Look at items P,Q & R on the diagram. They are all connected to a transformer with 12v supplied to the other side from the main switch. The CPU will modulate the current flow through each transformer (all four ignition coils for timing and the fuel pump relay for pressure), by varying the duty cycle of the waveform applied.
PS - An F-18 is 1990's technology. Now if you had said YF-22... :good2:
The coils (U) and the fuel pump relay (T) are NOT digital devices. They are not driven with TTL logic, and there is no transformer, they simply receive whatever voltage that the main switch provides. The reason there is "duty cycle" for the coils is to control the charging dwell time. Coils charge up very fast. Keeping the current flowing after they reach maximum charge will overheat the coil and reduce its life.
The ignition CPU changes the coil duty cycle to reach maximum charge just before the crank position where the plug needs to be fired. The CPU calculates the time to start charging the coil so it is ready when needed and attempts to avoid excess current flow through the coil. The duty cycle is also varied to account for the switch voltage. That's why the switch voltage is an input to the CPU. The dwell time (duty cycle) varies based on how much voltage is being supplied to the coils.
I still find it hard to believe a bunch of engineers would design a complicated reserve function that interfered with the ignition and could possibly cause a fouled plug.
Quote from: FJ_Hooligan on May 13, 2017, 06:44:28 PM
Quote from: ZOA NOM on May 13, 2017, 01:59:52 PM
If it was simply a cutout for power to the fuel pump, it wouldn't need to go through the CPU. Just wire a power lead to the pump and move on. It goes through the CPU because it does more than simply restore 12v to the fuel pump. I believe it does both simultaneously - changes the duty cycle of the ignition to give the feeling of a miss, and reduces the fuel pressure so the pump doesn't force fuel when the timing is off.
Look at items P,Q & R on the diagram. They are all connected to a transformer with 12v supplied to the other side from the main switch. The CPU will modulate the current flow through each transformer (all four ignition coils for timing and the fuel pump relay for pressure), by varying the duty cycle of the waveform applied.
PS - An F-18 is 1990's technology. Now if you had said YF-22... :good2:
The coils (U) and the fuel pump relay (T) are NOT digital devices. They are not driven with TTL logic, and there is no transformer, they simply receive whatever voltage that the main switch provides. The reason there is "duty cycle" for the coils is to control the charging dwell time. Coils charge up very fast. Keeping the current flowing after they reach maximum charge will overheat the coil and reduce its life.
The ignition CPU changes the coil duty cycle to reach maximum charge just before the crank position where the plug needs to be fired. The CPU calculates the time to start charging the coil so it is ready when needed and attempts to avoid excess current flow through the coil. The duty cycle is also varied to account for the switch voltage. That's why the switch voltage is an input to the CPU. The dwell time (duty cycle) varies based on how much voltage is being supplied to the coils.
I still find it hard to believe a bunch of engineers would design a complicated reserve function that interfered with the ignition and could possibly cause a fouled plug.
I still find hard to believe a bunch of [FJ Forum members would expend so much time and energy discussing] a complicated reserve function that interfered with the ignition and could possibly cause a fouled plug...!!! (...!!! added for emphasis)
But then if the fuel pump shuts off before the plug(s) foul would it not then involve the CDI, uh CPU unit... so perhaps the real question is who needs F-18 or even YF-22 technology when we have FJ(
H) technology...?
Smile gentlemen!
Mine don't work. And frankly I really don't care to fix it. I am old school and track my miles on the trip meter. When I am low on fuel I know it by habit. I know what fuel starvation is when I had vapor lock issues with a plugged fill cap on my '86. When my '86 cut out due to the RESERVE function it was just that, lack of fuel till the reserve switch was cycled. I gave that up when I converted to the 84/85 petcock. My '89 has never shown low fuel or acted like it was low till bone dry. I know the light works.
However, I enjoy the banter after a long day at work. I imagine the campfire warm and hissing from the Thermite, the lies about how fast we were, the truth about how old our bikes (and our selves) are. Talk of tires and oil and the O' SHIT moments we have all had. Mike said "Smile" and I take that as keep going and keep it friendly.
Discussion is good. Different points of view are good. Uncertainty is good. It's all good. Healthy.
With all the talented folks here, the truth will become evident.
I love this forum.
Respectfully, I present the following analysis of the Digital Ignition Control System diagram:
The first diagram shows inputs into the Digital Ignitor Unit (H) which contains some level of logic in the CPU/Microprocessor (O). Three outputs are 2 Ignition Coil Driving Circuits (Q and R) and a Fuel Pump Driving Circuit (P).
Starting from the upper right of the diagram, all power comes from the Main Switch (C). This is 12 volts from the battery.
Dropping down to the bottom of the diagram this 12V directly feeds the coils and the fuel pump relay. This would be the red/white wires that power the coils, there's no varying this voltage, it is whatever the battery is.
What I understand about ignition control and coils is as follows:
Current flowing through the coil primary circuit produces a field that induces (or creates) a voltage in the secondary winding. When the current flow in the primary is interrupted, the secondary voltage discharges through the spark plug causing the spark.
The secondary voltage has a threshold which must be achieved in order to create a spark. Anything less than this threshold voltage will NOT produce a spark. The primary coil circuit has a fixed resistance and pushing 12V through it determines how much current flows. The amount of time the current flows is proportional to the charge induced in the secondary coil winding. This is also known as ignition (or coil) Dwell Time. The Rated Voltage Circuit (N) is an input to the calculated Dwell Time. Higher voltage requires less Dwell Time.
The ignition controls when the plug fires by interrupting the ground side of the coil primary circuit. When the ignition has the coil connected to ground, the coil is charging. How long the coil is allowed to charge is the "Duty Cycle" or dwell time which determines how much charge the secondary coil circuit ultimately gets. Once the coil has reached maximum charge, additional charging dwell time will result in overheating and reduced life of the coil.
Going through the notes on this diagram;
#1 Determining proper ignition timing. The ignition must interrupt the primary coil circuit at the proper time to deliver the spark at the desired BTDC point. This is the ignition timing curve which will vary based on known variables such as RPM and state of the pressure sensor (F) and it's input to the CPU the Vacuum Control Circuit (L) (which is indicative of the throttle position). I do not know why there are 2 lines drawn between F and L, that would typically indicate that 2 signals are provided by the Pressure Sensor. I assume the Vacuum Control Circuit takes the signal from the Pressure Sensor and converts it into a logic signal that the CPU can comprehend. So, based on the ignition curve solution for when the spark is supposed to happen, the ignition will cut the coil primary circuit ground based on knowing the position of the crank via the Pickup Coil (G) and the Wave-Shape Shaping Circuit (M). The Wave Shaping circuit converts the analog sine-like signal produced by the Pickup Coil into a digital signal for the CPU. Knowing RPM, desired ignition advance and crank position, the CPU can determine the appropriate point to cut the ground and fire the plug(s). The CPU also calculates when to start charging the coil so it's ready for the spark event while avoiding overheating the coil.
#2 Sensing the engine revolution speed. As described above, this is required for proper ignition timing. The Pickup Coil signal is used to measure RPM for the CPU.
#3 Determining timing for switching on ignition coil (duty control). The CPU knowns when to fire the coil but it must also know when to reconnect the coil primary circuit to ground to "recharge" the coil. Under nominal conditions, there is a known minimum charging time (duty cycle) to assure enough secondary voltage is produced to spark the plug. Simple math in the CPU can solve for the crank position at which the coil circuit is turned on to get (at a minimum) threshold charging. The coil only needs to be charged to its rated secondary voltage. Additional dwell time will cause overheating. The dwell time is also modified to compensate for the switch/battery voltage seen at the coil.
#4 Increasing ignition primary current for starting the engine. This one kind of bothers me because it says "current." Up to this point I have maintained that the coil charging is a function of time given that fixed coil resistance and battery voltage produce a fixed current flow through the primary circuit. The coil charge (and duty cycle) is also a function of the current flow. For the ignition to have the ability to allow more current flow through the coils implies that the Ignition Coil Driving Circuits (Q and R) would have to have a varable series resistance that would allow more current to flow through the coil. That it only does this for starting means that whether it is time of current flow or amount of current flow, the end result is it doesn't matter once the engine is running. Maximizing voltage at the coil will produce more current flow and faster dwell time.
#5 Sensing engine stall. This has been explained. If the engine dies, the CPU shuts off the fuel pump. Pickup coil provides this signal
#6 Preventing over-revolution of the engine. Rev limiter! Again, pickup coil derived signal.
Conclusions? Based on this, I don't see how the ignition could cut out one coil without causing significant engine stumble. The coil is either going to fire or it's not. Even a degraded spark should ignite an air/fuel mixture.
The fuel level is monitored by the Fuel Sensor Input Circuit (I). When the level gets low enough, the reserve function kicks in. The Reserve Switch (D) and Reserve Switch Input Circuit (J) override the fuel pump relay cutoff and keep (or reapply) power to the pump.
The Fuel Pump Driving Circuit (P) is a ground path for the Fuel Pump Relay (T). When grounded, the relay is activated and the pump runs. If the Pickup Coil (G) and Wave-Shape Shaping Circuit (M) indicate that the engine is NOT running, then the fuel pump relay is activated for 5 seconds then shuts off. This signal also provides the logic to shut the fuel pump relay off when the ignition is on but the engine dies (a wreck).
The Ignition Coil Driving Circuits (Q and R) control the grounding of the coil charging circuits and are only for dwell and ignition timing.
Quote from: ribbert on May 13, 2017, 09:12:03 AM
Quote from: Mark Olson on May 13, 2017, 03:15:16 AM
Noel,
no fuel pump to go bad , I have a larger hose to fill my bowls.....
larger needle and seat that don't plug up , and living in California my fuel is good.
So yeah ,, I'm Glad.
As for the Reserve switch quest , it appears the fuel relay power is cut ...and what else? maybe it reduces power to conserve fuel to get you to the next gas station. An off the road stationary test is invalid.
Please conduct the following test for the good of the FJ collective.
attach sensors and probes to your ignition system to record input and out put voltages while operating your FJ.
now ride till you run out of gas and have to switch to reserve but don't switch till the engine dies and you can record your readings ... Like does the engine still get spark when you have stalled with the reserve switch still off.
Make sure you ride to a remote area as roadside tests are dangerous ..
I am counting on you.
Yeah, sure Mark. as soon as I finish the parabolic algorithms for re entry I'm working on I'll move onto the serious stuff. :biggrin:
Mark, I don't have a handle on your sense of humour and I don't want to offend you but I will go with my gut feel and assume your suggestions are tongue in cheek.
On the off chance you are being serious......
Why is an "off road stationary test" invalid. How does forward speed effect such a test?
You agree power is cut to the fuel pump. Why would you then have reduced spark as well if there is no fuel to ignite?
There is one point that many seem to overlook, it is just a fuel reserve function on a garden variety bike. Just how complicated were Yamaha going to make it?
I say again, there is no mistaking a bike running out of fuel with one running out of spark.
As for the bigger needle and seat (which really isn't that much bigger and the bigger hose which is irrelevent), they just let bigger crap through.
The benefit from the filter the pump allows you to run is less crap in your carbies. A fuel pump should only need replacing once in the entire life of your bike, hardly a biggy.
You are lucky to live somewhere with good fuel. We are also lucky here in that regard.
IMO
Noel
yes Noel , it is all in jest ..... I would think by now after all these years you would know when I am winding you up. thanks for playing. :drinks:
Quote from: FJ_Hooligan on May 13, 2017, 08:56:24 PM
Respectfully, I present the following analysis of the Digital Ignition Control System diagram:
The first diagram shows inputs into the Digital Ignitor Unit (H) which contains some level of logic in the CPU/Microprocessor (O). Three outputs are 2 Ignition Coil Driving Circuits (Q and R) and a Fuel Pump Driving Circuit (P)....
TL;DR
https://www.youtube.com/watch?v=fsOrty4RmSA (https://www.youtube.com/watch?v=fsOrty4RmSA)
:music:
Rock,
Perhaps you've seen my other video:
https://www.youtube.com/watch?v=yefVpB5GEio (https://www.youtube.com/watch?v=yefVpB5GEio)
Quote from: Mike Ramos on May 13, 2017, 07:16:11 PM
I still find hard to believe a bunch of [FJ Forum members would expend so much time and energy discussing] .......
Smile gentlemen!
Mike, it is far better use of forum resources (and time and energy) than repeatedly launching unprovoked, long winded tirades denigrating fellow members wouldn't you say?
Noel
And yes, I'm smiling.
aaaaawh, just when I was feeling the love.
Someone piss in your cornflakes Noel?
My goodness Noel,
Noel, it is just a little old reserve switch!
Deep breath & relax, repeat gently until the anger fades away or your until sanity returns...
Of course, pour a new bowl of cornflakes... unless the taste appeals to you! : :rofl2:
Laugh Noel, it is the best medicine...
Noel, I think resort to additional comments via P.M. if you deem it necessary...
As a reminder, this is not exclusively our Forum... let's at least let others enjoy it...
So, Hooli, if the TCI/DCI (aka CPU) calculates coil dwell time and adjusts the coil charging time according to voltage (among other factors) is the voltage is sensed at the CPU....or is the voltage sensed at the coil?
You could have 2 different values.... Voltage at the CPU could be different than charging voltage at the coil.
Coil relay mod vs Dwell times.
Before my coil relay mod, I was seeing ~11.2 volts at the coil thru my oem wiring harness.
After the coil relay mod, I'm seeing a full 14.4 volts (Transpo VR mod) at the coils above 2k rpm.
That is a considerable increase in energy to the coils, which begs the question:
If the CPU is calculating the coil dwell time, based on current it sees at the CPU, so, with the relay mod. the coils are now seeing 23% more energy than the CPU sees.....
Are not the coils potentially subject to overcharging and possibly overheating?
I've had my coil relay mod for several years now, with no ill effects...even in super hot weather riding.
Cheers Hooli....Thanks for helping me understand....
Pat,
According to "theory" the voltage and the CPU and the coils needs to be the same to properly calculate coil dwell time. As we know from the headlight relay mod, the actual voltage is a function of resistive wiring losses. Without directly measuring the voltage at the coils and the CPU I don't know for sure.
Your ~11.2 volts for the OEM wiring, was that at idle or 2K RPM? So we can compare apples to apples.
Looking at the wiring diagram it's kind of hard to decipher. Looks like the Ignitor Unit get its voltage source directly from the main fuse box. The coil power wire comes from the Relay unit. It looks like the input power for the Relay unit is the Brown wire. Following the brown wire shows that there are numerous branches off of this circuit. It appears to power almost everything on the bike.
From this, I can only assume that the CPU voltage MAY be more direct and higher than the voltage showing up at the coils (direct measurement would confirm). Maybe that's why the coil relay mod is so successful and doesn't harm the coils. The CPU doesn't know the coils are at a lower voltage so the dwell time is shorter than it really needs to be. Adding the relay gives the coils more voltage which would make up for the short dwell time.
All just a guess. I would think a 23% increase in voltage would be significant. Especially since I think there is a square somewhere in the math.
Quote from: FJ_Hooligan on May 13, 2017, 06:44:28 PM
Quote from: ZOA NOM on May 13, 2017, 01:59:52 PM
If it was simply a cutout for power to the fuel pump, it wouldn't need to go through the CPU. Just wire a power lead to the pump and move on. It goes through the CPU because it does more than simply restore 12v to the fuel pump. I believe it does both simultaneously - changes the duty cycle of the ignition to give the feeling of a miss, and reduces the fuel pressure so the pump doesn't force fuel when the timing is off.
Look at items P,Q & R on the diagram. They are all connected to a transformer with 12v supplied to the other side from the main switch. The CPU will modulate the current flow through each transformer (all four ignition coils for timing and the fuel pump relay for pressure), by varying the duty cycle of the waveform applied.
PS - An F-18 is 1990's technology. Now if you had said YF-22... :good2:
The coils (U) and the fuel pump relay (T) are NOT digital devices. They are not driven with TTL logic, and there is no transformer, they simply receive whatever voltage that the main switch provides. The reason there is "duty cycle" for the coils is to control the charging dwell time. Coils charge up very fast. Keeping the current flowing after they reach maximum charge will overheat the coil and reduce its life.
The ignition CPU changes the coil duty cycle to reach maximum charge just before the crank position where the plug needs to be fired. The CPU calculates the time to start charging the coil so it is ready when needed and attempts to avoid excess current flow through the coil. The duty cycle is also varied to account for the switch voltage. That's why the switch voltage is an input to the CPU. The dwell time (duty cycle) varies based on how much voltage is being supplied to the coils.
I still find it hard to believe a bunch of engineers would design a complicated reserve function that interfered with the ignition and could possibly cause a fouled plug.
Well, I didn't say they were digital devices, but the internal components of the CPU are, and the outputs to P,Q & R are not simply grounds. They are square waveforms that determine duty cycle by placing and removing the grounds to those devices. Also, the windings of the Fuel Pump Relay, and the Coils are indeed transformers, as you described above.
In any event, it remains a mystery, and mine has never worked as far as I know, and the bike runs fine.
edit: just found this on http://www.yamaha-tech.com/wiki/Yamaha_FJ1200 (http://www.yamaha-tech.com/wiki/Yamaha_FJ1200)
Electrical system
The FJ1200 features a standard 12 Volt electrical system. The alternator and starter motor are mounted behind the cylinders. Yamaha's self cancelling indicator unit is used and a variable resistance Level sensor is used to monitor engine oil contents with associated warning lights. A large fuel gauge is provided as is a low level warning light. Denso Capacitor discharge ignition is used in conjunction with two Ignition coil.
The FJ1200 fuel reserve system used in later models is unusual in that when the fuel level reaches approximately 5 litres remaining ignition is cut to two cylinders giving the impression that the vehicle is running out of fuel, a reserve switch mounted in the fairing restores the cut cylinders allowing the rider to continue normally.[7][8]
Quote from: Mike Ramos on May 14, 2017, 11:41:34 AM
Deep breath & relax, repeat gently until the anger fades away or your until sanity returns...
Mike, I'm sorry you missed the humour in my post of the irony in yours - maybe a bit subtle.
Deep breath & relax, repeat gently until the bias fades away or until your humour returns.... :biggrin:
Noel
Quote from: ZOA NOM on May 15, 2017, 01:34:15 AM
The FJ1200 fuel reserve system used in later models is unusual in that when the fuel level reaches approximately 5 litres remaining ignition is cut to two cylinders giving the impression that the vehicle is running out of fuel, a reserve switch mounted in the fairing restores the cut cylinders allowing the rider to continue normally.[7][8]
That's weird. :scratch_one-s_head: A couple of times I have run the tank almost dry on my '92 - refill with 20L (capacity 22L apparently). I've never experienced the above scenario. So that means.... I dunno'. Guess I'll just keep riding instead of worrying. :yes:
Quote from: ZOA NOM on May 15, 2017, 01:34:15 AM
.....The FJ1200 fuel reserve system used in later models is unusual in that when the fuel level reaches approximately 5 litres remaining ignition is cut to two cylinders giving the impression that the vehicle is running out of fuel.
Rick, I don't know when you joined the forum but this idea was dismissed years ago, even by the diminishing spark believers, for reasons that everyone agrees on. The behaviour of the engine when low on fuel is not consistent with this happening. If this was the case, the engine would smoothly (sort of) run along on 2 cylinders until it drained
all the fuel in the tank, it doesn't.
One thing everyone agrees on is that it starts out as a barely perceivable loss of power and progresses through to stumbling, major rough running and eventually dies completely. Just cutting from 4 to 2 cylinders would not do this.
I believe this statement was originally attributed to a journo whose source of information may have been no more than his own speculation and it then took on a life of its own.
Maybe the spark has been programmed to mimic the power being cut off to the fuel pump so it feels like it's running out of fuel? But hang on, if you were going to that, why wouldn't you just ....... :biggrin:
Noel
Quote from: Pat Conlon on May 14, 2017, 02:06:59 PM
Before my coil relay mod, I was seeing ~11.2 volts at the coil thru my oem wiring harness.
After the coil relay mod, I'm seeing a full 14.4 volts (Transpo VR mod) at the coils above 2k rpm.
.... so, with the relay mod. the coils are now seeing 23% more energy .....
Are not the coils potentially subject to overcharging and possibly overheating?
Pat, normal charge rate for a 12v system is ~14.2 V. That is what your coil was designed to operate at. It was not designed to operate around voltage drop through the harness (11.2V).
You have not exceeded the voltage by 23%, you have returned it to it's normal operating specs.
IMO
Noel
Quote from: ZOA NOM on May 15, 2017, 01:34:15 AM
Well, I didn't say they were digital devices, but the internal components of the CPU are, and the outputs to P,Q & R are not simply grounds. They are square waveforms that determine duty cycle by placing and removing the grounds to those devices. Also, the windings of the Fuel Pump Relay, and the Coils are indeed transformers, as you described above.
In any event, it remains a mystery, and mine has never worked as far as I know, and the bike runs fine.
Rick,
I apologize for misinterpreting your original statement. My response appears to be harsh, I did not mean to insult.
When you say yours doesn't work, do you mean that you must have the reserve switch on all the time? If so, do you know if your low fuel light still works?
DavidR.
Quote from: ribbert on May 15, 2017, 07:27:44 AM
Quote from: ZOA NOM on May 15, 2017, 01:34:15 AM
.....The FJ1200 fuel reserve system used in later models is unusual in that when the fuel level reaches approximately 5 litres remaining ignition is cut to two cylinders giving the impression that the vehicle is running out of fuel.
Rick, I don't know when you joined the forum but this idea was dismissed years ago, even by the diminishing spark believers, for reasons that everyone agrees on. The behaviour of the engine when low on fuel is not consistent with this happening. If this was the case, the engine would smoothly (sort of) run along on 2 cylinders until it drained all the fuel in the tank, it doesn't.
One thing everyone agrees on is that it starts out as a barely perceivable loss of power and progresses through to stumbling, major rough running and eventually dies completely. Just cutting from 4 to 2 cylinders would not do this.
I believe this statement was originally attributed to a journo whose source of information may have been no more than his own speculation and it then took on a life of its own.
Maybe the spark has been programmed to mimic the power being cut off to the fuel pump so it feels like it's running out of fuel? But hang on, if you were going to that, why wouldn't you just ....... :biggrin:
Noel
LOL! A wiki page using Haynes and Clymer manuals as a reference.
Not exactly what I would call "reliable" sources...... :gamer:
Quote from: FJ_Hooligan on May 15, 2017, 10:55:37 AM
Quote from: ZOA NOM on May 15, 2017, 01:34:15 AM
Rick,
When you say yours doesn't work, do you mean that you must have the reserve switch on all the time? If so, do you know if your low fuel light still works?
DavidR.
I know that on my '89, since the Speed Hut gauges were installed. The reserve switch is required to be activated and yes, the OEM low fuel level still works as designed.
I didn't get a chance to remove the fuel sender over the weekend. The weather was too nice to be stuck in the garage. I actually rode both of the bikes this weekend.
Fred
The Wiki page that is referenced, was actually written initially by one of the Forum members here.
I forget his name, but believe he was in Texas???
I'm pretty sure he mostly used information that had been circulated around this forum.
He went by nickname "Fintip" or something like that?
Alan, you are correct. Kyle AKA Fintip started the page and used what information he had access to.
Quote from: FJ_Hooligan on May 15, 2017, 10:55:37 AM
Quote from: ZOA NOM on May 15, 2017, 01:34:15 AM
Well, I didn't say they were digital devices, but the internal components of the CPU are, and the outputs to P,Q & R are not simply grounds. They are square waveforms that determine duty cycle by placing and removing the grounds to those devices. Also, the windings of the Fuel Pump Relay, and the Coils are indeed transformers, as you described above.
In any event, it remains a mystery, and mine has never worked as far as I know, and the bike runs fine.
Rick,
I apologize for misinterpreting your original statement. My response appears to be harsh, I did not mean to insult.
When you say yours doesn't work, do you mean that you must have the reserve switch on all the time? If so, do you know if your low fuel light still works?
DavidR.
No harshness perceived, Dave. I actually have no idea which position it's in. I exclusively use the trip meter, and I don't believe there's a low fuel light on my 93.
I see now why this topic was abandoned.... :)
My last comment on this (maybe)
I liked this topic when it was originally brought up because it had all the elements of a good thread. Of interest to many, a mystery to all and solveable by most and would therefore lead to a conclusion.
I have just two questions:
For all the speculating, circuitry analysis, theorising and hypotheses offered up....
Q1 - Why didn't anyone conduct their own tests? and be done with it.
Q2 - Why was my test not conclusive? and can anyone point out where it was flawed?
Quote from: link=topic=16857.msg170237#msg170237 date=1494830055
.......In any event, it remains a mystery.......
An opinion it seems still shared by many. :dash2:
Noel
Quote from: ribbert on May 17, 2017, 09:32:47 AM
...Q1 - Why didn't anyone conduct their own tests? and be done with it....
Noel
I can only answer this Q for myself: too busy, haven't gotten to it yet.
I'm going to isolate the fuel supply to my 4gas/synch testing/maint fuel tank. It's a gravity feed tank I hang of the bars/triples (IE: fuel pump out of the loop).
Then manipulate the sender to give the low light. If the bike stumbles, then manipulate to turn the low fuel light off. Repeat the process a couple times to ensure it actually is repeatable. Probably try a couple RES switch on/off cycles too.
Since the debate seems to be whether it's the ignition or the fuel, seems logical to isolate the systems from each other and test. Since you can't isolate the ignition and expect the bike to run properly, that just leaves the fuel system to "inhibit".
If the bike stumbles with the light on and recovers with the light off, that's evidence enough for me as to what is happening.
But that will also
only confirm the ignition has a part in the aforementioned "stumble", it won't disprove there's not something happening with the fuel pump at the same time. That's for others to debate, I have no interest in it past my own little "test" for curiosities sake.
:wacko3:
Just gotta get some free time to give it a try!
:dance2:
Even with the gravity feed directly to the carbs, with the low fuel level in the tank, you will hear the pump cycle on when you click on reserve. Just run a hose from the pump output to a gas can.
That's fine. Rule out ignition, then the rest is obvious.
We know the fuel pump is involved (at least some of us)
The question: Is the ignition *also* involved? Will be answered.
Quote from: Pat Conlon on May 17, 2017, 11:25:35 AM
Even with the gravity feed directly to the carbs, with the low fuel level in the tank, you will hear the pump cycle on when you click on reserve. Just run a hose from the pump output to a gas can.
That's fine. Rule out ignition, then the rest is obvious.
We know the fuel pump is involved (at least some of us)
The question: Is the ignition *also* involved? Will be answered.
I will
try to listen for the pump. But when my "box o' rocks" is running, it's hard to hear anything at all...... :wacko1:
Pump won't have fuel in it, tank will be off the bike. Multi-meter or test light would be a better indication and what I will probably use. It will also do away with the "5 seconds and no pressure = pump shut off" logic of the pump itself...
Not sure if I'll get to it this weekend. Sat I'm picking the VentureMax up from storage, Sunday or Monday we're towing the camper to the seasonal site. FJ is running OK so sync and CO2 is kinda low on the "to do" list. I also have the RPM filter adapter, new gauge lens and chain/sprockets (and a bunch of other little things) to do as well...Plus, I have to find some time to get back to modifying the VentureCruise system to the FJ.
What I enjoyed about the fuel pump FJ's is the long fuel hose running from the filter to the fuel pump.
When it was time to sync the carbs, I left the tank connected and simply rotated the tank 180 degrees and rested the tank on the subframe. This allowed plenty of room to the carbs.
Looking forward to your results .... Thank you in advance, for taking your time to do this.
Quote from: Pat Conlon on May 17, 2017, 04:08:23 PM
What I enjoyed about the fuel pump FJ's is the long fuel hose running from the filter to the fuel pump.
When it was time to sync the carbs, I left the tank connected and simply rotated the tank 180 degrees and rested the tank on the subframe. This allowed plenty of room to the carbs.
Looking forward to your results .... Thank you in advance, for taking your time to do this.
Yessir, I rotated the tank once. Works, but I never became comfortable with it perched on the frame rails.
I'm usually a prime target for Murphy if I'm not watching for him, so I remove the tank and use my aux tank. I use one like this:
(http://i.ebayimg.com/images/g/-mIAAOxy-WxTAr1Q/s-l300.jpg)
If it drops on the floor it doesn't spill, has a shut off valve on the bottom, holds plenty of fuel for extended running and I have a hook system that I hook on the bars or triples. A bungy holds it snug, just for insurance.
That Murphy, he's a b@st@rd.....
I believe Pat meant on the fuel pump bikes it is possible to spin the tank 180 and use the two rear mounting bolts to hold the tank in place. I believe I have seen my dad do this at a rally possibly. We also have an aux tank that is on a stand with fans and tools.
Robert - RPM
Quote from: racerrad8 on May 17, 2017, 05:47:51 PM
I believe Pat meant on the fuel pump bikes it is possible to spin the tank 180 and use the two rear mounting bolts to hold the tank in place. I believe I have seen my dad do this at a rally possibly. We also have an aux tank that is on a stand with fans and tools.
Robert - RPM
Hmm, never thought of seeing if the bolts would work with the tank reversed. Would be a good work around on the side of the road or something.
I've thought of building a stand to hold my 4/5 gas and the rest of the stuff, but I just don't have the room for it.
An 83 Venture, an 83 Mustang, the FJ and all my tools don't make for a lot of space left over in a 1+ garage space.....
:(
Here is my experience with my 86. No electric fuel pump on my model. I wanted to satisfy my curiosity to see if/how the reserve switch worked. I drove the bike until the red low fuel light illuminated solidly. I had driven about 300k on the tank of fuel before the low light started to flicker, much was pretty "spirited" driving. With the low light on solidly my gauge was two needle widths below "E", almost on the pin. I drove it with the reserve switch off for approximately 60 kilometres, until running out of fuel. Switching to reserve didn't help, obviously the tank was bone dry. I was carrying a 1l fuel bottle which eventually got the bike started. It made no difference which position the reserve switch was in, the 1l continued to flow so I surmise my reserve valve solenoid has frozen in the reserve position as that small amount of fuel in the tank wouldn't normally be picked up in the "run" position. I drove a short distance to a fuel station and added 21.5l of fuel. The tank holds 22l so I know that it was fully drained when I ran out.
My points are: the gauge works, the low light works, the reserve switch/fuel solenoid doesn't work and is stuck in the reserve position allowing the tank to be drained completely. I see no point adding a manual type fuel valve, it would be pretty inaccessible under the tank. Next time I have the tank off I may test the solenoid with 12 volts to see if it moves. I can live with the gauge, light and odometer, but my bike is near mint and it would be nice to have it working as intended.
I'd like to know if 12v holds a properly functioning valve in the run or reserve position. I'm assuming that the valve is normally in the reserve position with no power to it and when the bike is running and the reserve switch is not in the "on" position, the valve is receiving 12 volts to trigger the solenoid to take fuel from the taller of the two tank inlets. Can anyone confirm? I assume that when the bike begins to sputter, switching to reserve will remove the power from the solenoid and switch the valve to reserve.
Thanks,
Dave
I don't want to know how or why it works. I want to know in what position is the reserve disabled? RES or ON. I read through 10 pages and never saw a clear answer. Thanks and may this thread rest in peace.
On
I would agree Pat, on my 86, depressing he rocker "up" to the "RES" position reveals a black sticker on the rocker "RES". In the "down" position, the black "RES" sticker is hidden.
I'm good with all that, but as I found on my bike, the tank will drain to completely empty no matter what position the switch is in. Bad switch, wiring or tank valve solenoid, all which I can check when I get the urge.
I'd hoped that someone can confirm without doubt how the system is supposed to work. It would seem that the simple solution from Yamaha would be an electric solenoid fuel valve, similar in mechanical function to a manual reserve valve (with different length fuel pick-up tubes) controlled by the rocker switch. No fuel pump disconnection, no coil interruption etc.
Drive the bike with the switch down until the fuel level drops, at some point the fuel level will fall below the longer pickup tube and the bike will starve. Flip the rocker and the solenoid will trigger fuel flow from the reserve tube. Sometime during this process, the low fuel light will illuminate, hopefully just prior to requiring a switch to reserve.
Lots of posts about this, but I've not found a definitive answer for the 86 model.
I can tell you this, there is not different draw tubes on the petcock. The petcock has a single inlet.
Unfortunately, in my opinion, there is not a "without doubt" conclusion oh how the reserve system works. As you have already read in the other posts, there is a lot of speculation and theory but no documented proof of the system functions
Randy - RPM
With Dave's experience on his '86, we can rule out ignition interrupt and a function of the reserve.
Quote from: racerrad8 on June 15, 2017, 10:52:47 AM
I can tell you this, there is not different draw tubes on the petcock. The petcock has a single inlet.
From images of the part, I agree. So my theory now is that something (gauge float lever or low fuel light) triggers the reserve valve to close. Your engine starts to stumble, prompting you to move the rocker switch which either adds or removes 12v to the solenoid. I'm betting that the solenoid is normally open, so somehow the low fuel/fuel gauge triggers something through the rocker switch to cause the fuel valve solenoid to change its state.
Hard to believe that 31 years later with all the knowledge here that it hasn't been discussed and confirmed.
I may get out the multimeter and check the wires to the rocker switch now that my tank is full and check it again when I drive it to empty.
Standby.
Dave
And yes, my ignition was working fine when I ran out of fuel, from the time I noted the beginning of lack of fuel stumble to complete shutdown took me about a kilometer at 60kph. Nothing shut down the ignition.
I read a 2011 post on MCN from a guy with a similar problem that unfortunately has no solution. The guy references a Haynes manual and a "fuel reserve control unit" located behind the rear master cylinder. Anyone familiar with this module? I don't have a Haynes manual.
Quote from: Pat Conlon on June 15, 2017, 11:16:51 AM
With Dave's experience on his '86, we can rule out ignition interrupt and a function of the reserve.
Pat, are you sure Dave's bike is not stuck on reserve based on his new theory...?
Dave,
Based on this statement:
Quote from: Super on June 15, 2017, 04:17:43 PM
...Your engine starts to stumble, prompting you to move the rocker switch which either adds or removes 12v to the solenoid.
Dave
When you switched the reserve function, was the stumble gone instantaneously or did your bike stumble for several seconds while the gravity fuel flow refilled the carb bowls?
If the stumble was gone instantly, do you think the fuel can flow that quickly down into the carbs to refill them?
Also, do you think based on the wiring diagram provided earlier in the post, the switch might also have an effect on the CDI. (See reply #9) I know this is for a fuel pump version, but there is a total of six (6) input sources to the CDI and only three (3) outputs. On this diagram one of them controls the fuel pump, the other two outputs control the ignition coils.
Could the CDI alter the dwell/saturation time of the coils for diminished spark to cause the stumble?
By the way, I rode my wife's 86' bike this week and my experience is again; when the low fuel light comes on the bike begins to stumble, I rock the switch to "reserve" and the stumble goes away instantaneously...
So, unfortunately there is still doubt. Until I am to purchase a dyno and hook up an oscilloscope to see the secondary KV output of the coils I will continue to have my doubts of the experiences, theories and speculations on how the reserve system functions.
I have been told there is another forum member who has access to a different wiring diagram and also believes the CDI is part of the "reserve" function....more to come...someday.
I also have an experiment planned with Mike Ramos and the use of his auxiliary tank. When we get that sorted out in the next couple of months, the findings will be posted.
Until then, I will not continue to speculate on how the reserve system works, my post today was simple to advise there was no dual height draw tubes. My additional questions are based on your experiences and theory because Pat has clearly stated...
Quote from: Pat Conlon on June 15, 2017, 11:16:51 AM
With Dave's experience on his '86, we can rule out ignition interrupt and a function of the reserve.
Randy - RPM
I was driving very gently at 60 kph when it started to surge a bit. This was after the low fuel light had been on for many kilometers. I switched the rocker up to reserve but the bike ran out of gas about 900 meters down the road. The tank was bone dry. The 1 litre bottle of gas (took a lot of cranking to prime the carbs btw) carried me to the closest gas station where I pumped 21.5l into the 22l tank.
Yes, I'd say the valve is stuck open. I don't understand what triggers it to close, perhaps something that relates to this "fuel reserve control unit" referred to in another post?
As I said, I drove over 30 miles with the reserve light on solidly before it began to stumble and ran out of gas. There must be something that triggers the fuel valve to close when the low fuel light first illuminates.
Dave
The bike will stumble and fart for some time when it runs out of gas, mine ran almost a kilometer before it died. If I had an operating reserve and switched the reserve on at the first sign of stumbling, it would only take a matter of seconds for the float bowls to fill up and restore normal power, imo. Randy, my low light flickers for a few miles prior to illuminating solidly. Does your bike stumble when the light begins to flicker or does it start to starve only when the light is on solidly?
Quote from: racerrad8 on June 15, 2017, 06:44:19 PM
Quote from: Pat Conlon on June 15, 2017, 11:16:51 AM
With Dave's experience on his '86, we can rule out ignition interrupt and a function of the reserve.
Pat, are you sure Dave's bike is not stuck on reserve based on his new theory...?
Yes, I believe Dave's petcock is stuck on reserve....and my statement was not based on theory, it's based on evidence.
Dave's evidence shows that he completely drained his tank with no hint of ignition interrupt.
Quote from: Pat Conlon on June 15, 2017, 07:40:35 PM
Quote from: racerrad8 on June 15, 2017, 06:44:19 PM
Quote from: Pat Conlon on June 15, 2017, 11:16:51 AM
With Dave's experience on his '86, we can rule out ignition interrupt and a function of the reserve.
Pat, are you sure Dave's bike is not stuck on reserve based on his new theory...?
Yes, I believe Dave's petcock is stuck on reserve....and my statement was not based on theory, it's based on evidence experience
Dave's evidence experience shows that he completely drained his tank with no hint of ignition interrupt.
FTFY...
You need even said so in your posted
theory.Randy - RPM
Quote from: Super on June 15, 2017, 06:59:02 PMRandy, my low light flickers for a few miles prior to illuminating solidly. Does your bike stumble when the light begins to flicker or does it start to starve only when the light is on solidly?
My 86 starts stumbling as the light starts glowing. I can jamb on th front brake, shut the light off and the light goes out and the stumble stops immediately.
My wife's bike bulb goes to a bright illumination before it starts to stumble. It glows lightly, getting brighter as the level drops. Since I can't watch it all the time, I'm not sure how much brighter it gets. I have usually switched over already because the bike runs so poorly.
Again, there is no delay on the return of proper engine operation at the flip of the switch.
Randy - RPM
My 85 has an 86 tank. The 86 tank came with the electrically operated reserve petcock which I'm using because it is smaller and easier to put the gas line on. The connector for the petcock isn't connected and it will drain the tank. When the reserve light comes on solid it is time for more gas. Reserve function equals an open circuit.
Chris
I like to know how things work, but this is one that I'm happy to give up on.
With newer bikes having a fuel pump and the older ones not, three different petcock designs over the years, old magazine articles referring to a coil shutdown, some bikes having a low fuel light and some without the light, the changing approach to the reserve function by Yamaha over the generations of FJs, reserve switches that may or may not work after 25+ years on a specific owner's bike, possible fault with an electrically operated petcock and any other intermittent failures after 30+ years, the permutations here are mind boggling. It's no wonder there are no solid conclusions.
Even to begin, one would have to first separate the generations (or specific year being discussed), then each system (switch, fuel light, petcock, etc...) would have to be known to be functioning as it should be (even that is in question). Only then could a test be done to see if it's a coil, or a petcock or a fuel pump cutoff. Then you have to start over for another generation/year.
I applaud those who are hanging in there to find the answers!
Well, my 89 isn't going to shed any light on the issue. I finally got the level low enough to bring the fuel light on when leaning on the side stand and.....nothing.
With the res switch on or off it happily rattled along. No change at all. Seems I'm on res all the time I guess. No big, I use my trip odo anyways, its just something I've always done. I might chase it down this winter to see if it's a switch issue or something in the wiring....
Quote from: Capn Ron on June 16, 2017, 01:54:55 AM
I like to know how things work, but this is one that I'm happy to give up on.
With newer bikes having a fuel pump and the older ones not, three different petcock designs over the years, old magazine articles referring to a coil shutdown, some bikes having a low fuel light and some without the light, the changing approach to the reserve function by Yamaha over the generations of FJs, reserve switches that may or may not work after 25+ years on a specific owner's bike, possible fault with an electrically operated petcock and any other intermittent failures after 30+ years, the permutations here are mind boggling. It's no wonder there are no solid conclusions.
Even to begin, one would have to first separate the generations (or specific year being discussed), then each system (switch, fuel light, petcock, etc...) would have to be known to be functioning as it should be (even that is in question). Only then could a test be done to see if it's a coil, or a petcock or a fuel pump cutoff. Then you have to start over for another generation/year.
I applaud those who are hanging in there to find the answers!
Ron, the reserve switch function on the fuel pump models was settled to most folks satisfaction a couple of years ago. I'm sure the earlier models are no more complicated to figure out.
The scenario you outline of nutting out all the different generations and systems really just describes an ordinary day for a mechanic or auto electrician, it's their job and to them it's not difficult or confusing.
Noel
Quote from: ribbert on June 18, 2017, 07:50:56 AM
Ron, the reserve switch function on the fuel pump models was settled to most folks satisfaction a couple of years ago. I'm sure the earlier models are no more complicated to figure out.
The scenario you outline of nutting out all the different generations and systems really just describes an ordinary day for a mechanic or auto electrician, it's their job and to them it's not difficult or confusing.
Noel
Well, get right on that then! :lol:
My KLR will stumble and die when it runs out of fuel, and by the time it takes me to return my left hand to the handlebar after twisting the valve to "reserve" the carb has refilled enough to keep the bike running. I know, it happened to me last week whilst among highway traffic. My old Seca 900 would fire back up almost immediately too so I can attest float bowls fill quickly enough to give the impression the ignition was cut off.
Something on my 86 is not prompting the fuel valve to close once the fuel level drops to a low level. Or that "something" is prompting the valve to close and the valve itself is stuck open. I'll pull the tank and check the valve but it would be helpful if someone could confirm what triggers the valve to open and close.
Dave