reserve switch

[Pat Conlon]

So if I read the explanation correctly, if they do not flip the reserve switch or it malfunctions the fuel pump does not turn on and the bike runs out of fuel?

Yep, it happened to my buddy Paul....the first time he rode my '92.
I forgot to tell him about the reserve switch. He was riding in front, the bike started sputtering, he slowed down thinking something was wrong and ended up stopped by the side of the road with a dead engine.
His comment was "shit the fuel light just came on...that's not much of a warning.."
Flipped the switch to 'R' ....the fuel pump started clicking....and away we went.

I totally forgot about the switch because my '84 does not have one....

[movenon]

So if I read the explanation correctly, if they do not flip the reserve switch or it malfunctions the fuel pump does not turn on and the bike runs out of fuel?

Yep, it happened to my buddy Paul....the first time he rode my '92.
I forgot to tell him about the reserve switch. He was riding in front, the bike started sputtering, he slowed down thinking something was wrong and ended up stopped by the side of the road with a dead engine.
His comment was "shit the fuel light just came on...that's not much of a warning.."
Flipped the switch to 'R' ....the fuel pump started clicking....and away we went.

I totally forgot about the switch because my '84 does not have one....

See, more proof.... Its the fuel not the igntior doing some cosmic miss fire of two cylinders.. The bowls do not have to be dry to cause a miss fire, probably more accurately a rough running condition leading to fuel starvation thus leading to profanity.... 
George 

[FJ_Hooligan]

So if I read the explanation correctly, if they do not flip the reserve switch or it malfunctions the fuel pump does not turn on and the bike runs out of fuel?

It will be interesting to see how long you can ride, without turning on the reserve before the bike dies. It would also be interesting to open a bowl drain and see how much fuel is actually in the bowl in comparison to the normal as controlled by the float level.

My experience was a tank venting problem, so I can't vouch that the reserve function works the same way.  I was able to go about 3 miles.  I recall feeling the engine start to struggle.  I had gotten caught in the rain and thought maybe a coil had gotten wet.  When I felt the stumble, I thought I would just open it up and drive through it by heating the coil up and drying it off.  At first It thought it was working because when I rolled on the throttle, the motor picked back up and everything seemed fine.  For about 1/2 of a mile when the stumble returned and quickly followed by the engine totally dying.  I pulled in the clutch and coasted as far as I could before pulling to the side of the road.

About 10 minutes of confused troubleshooting before I discovered the venting problem.

[movenon]

So if I read the explanation correctly, if they do not flip the reserve switch or it malfunctions the fuel pump does not turn on and the bike runs out of fuel?

It will be interesting to see how long you can ride, without turning on the reserve before the bike dies. It would also be interesting to open a bowl drain and see how much fuel is actually in the bowl in comparison to the normal as controlled by the float level.

My experience was a tank venting problem, so I can't vouch that the reserve function works the same way.  I was able to go about 3 miles.  I recall feeling the engine start to struggle.  I had gotten caught in the rain and thought maybe a coil had gotten wet.  When I felt the stumble, I thought I would just open it up and drive through it by heating the coil up and drying it off.  At first It thought it was working because when I rolled on the throttle, the motor picked back up and everything seemed fine.  For about 1/2 of a mile when the stumble returned and quickly followed by the engine totally dying.  I pulled in the clutch and coasted as far as I could before pulling to the side of the road.

About 10 minutes of confused troubleshooting before I discovered the venting problem.

Yea, they should put a notice decal on the fuel cap "in case of engine failer open cap" 
George

[Mike Ramos]

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.

Now on to a perhaps a touchy subject re: verification of statements.  While not part of this subject, it was brought up by another and in my opinion is not correct.

         "I've never seen a demand for information you have posted to be verified in such a manner."

Actually, any claim made by the gentleman from RPM is indeed subject to verification; by all of those who purchase the various products offered by RPM; both official Yamaha parts and FJ specific items developed specifically for the FJ's.  

Ride safe,

Mike Ramos.

[Pat Conlon]

That's a interesting point Mike....

In absence of conclusive bench testing on the fuel pump models...Let's talk about the 86/87 reserve switch function....

Hey Randy, I have an idea....Can you take one of your new 86/87 petcocks and hook it up to a 12v source and see if you can blow thru it?
We know vacuum opens/closes the petcock, and I suspect a 12v signal closes it...  

Or...if the reserve interrupt on the '86/87 was ignition, then folks who have changed over to the straight vacuum 84/85 petcock would still have the ignition interrupt feature, correct?
I wonder if our Red Power Ranger noticed this?

Can anyone post a wiring diagram for the '86/87s?

[Capn Ron]

Hey Randy, I have an idea....Can you take one of your new 86/87 petcocks and hook it up to a 12v source and see if you can blow thru it?
We know vacuum opens/closes the petcock, and I suspect a 12v signal closes it...  

I wondered this as well...In a gravity feed fuel system, to stop the fuel from flooding the cylinders and working its way into the crankcase (experienced this day ONE on my Seca 550), the needles and seats are the only defense.  Because of this, whenever you stored your bike, you were supposed to turn the fuel tank petcock to "OFF".

Fast forward to the fuel pump late model FJs...The fuel pump itself will stop the flow of fuel *before* the carburetors by doing nothing more than shutting the bike down via the ignition key.

Somewhere in the middle...86/87 there was a more expensive petcock used with a wired connection.  I wondered if this was a stop-gap solution to the fuel flooding problem before the fuel pump solution was implimented.  I'm pondering if the 86/87 petcock NEEDS a 12V signal to flow fuel...therby cutting the fuel supply when the bike is parked to solve the problem of filling the cylinders/crankcase with gasoline if the needles and seats are leaking.

Pat above says that it opens via vacuum pressure...so what exactly is happening with the electrical connection?

Cap'n Ron. . .

[Pat Conlon]

Ron, the opening and closing of 86/87 petcock is done by engine vacuum taken off the #2 intake manifold.
As in, when vacuum is present (engine starting or running) the petcock opens...and gas flows. When the vacuum stops, (engine off) the petcock closes.
No worries about flooding the engine....when all is working correctly...

I suspect the wires going to the '86/87 petcock are to activate a electric solenoid which closes the petcock (even when the vacuum signal is present) This happens when the low fuel sensor in the tank sends the signal to the petcock.
Flip the reserve switch to reserve and the electrical signal stops and the solenoid opens up and gas starts flowing again...
My theory anyway....I don't have a '86/87 .....so I'm just guessing. 
Hooking up a power source to the '86/87 petcock would be interesting. You would need to also provide a vacuum signal to the petcock to hold it in the open position, while you checked to see if the solenoid closed off the flow.

[Capn Ron]

Ahhhh...I gotcha Pat.   The vacuum tap opens the petcock to allow fuel to flow.  If the engine isn't running, the fuel can't overwhelm the carbs/cylinders.  Simple enough.  You're wondering if the electrical part of the '86/'87 petcock is an override.  Shutting down the fuel supply as a response to the sensor no longer sensing fuel at its preset level even while there is vacuum present.

I'm now curious about this too...  But then again...I'm a curious individual.   

Cap'n Ron. . .

[Harvy]

Or...Harvy, maybe when you changed over to the aftermarket ignition you lost your "turbo fill" ability of the fuel pump when the reserve switch is activated allow the engine to return to the proper running cycle instantly.


So, the question still remains...

CDI interrupt?
Fuel Pump interrupt?

Or a combination of both?



After all this is the "digital campfire" where we can all learn something.

Randy - RPM

I'm not certain that its one way or the other or a combination of both. The more I'm reading here, the more I'm thinking that over the generation changes, Mr Yamaha decided to change the nature of the beast?

As to the "tubo fill", I can't really say as I don't have an OEM pump anymore either.

All I can say with certainty is that on MY '91 FJ, with an aftermarket pump and no CDI connect to the loom, the Reserve switch is controlling the fuel pump, not the ignition.

Take from that what you will folks.

Cheers
Harvy

[ribbert]

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.  

Mike Ramos.

C'mon, Both??  A secondary, redundant low fuel warning system on a motorbike?

Now on to a perhaps a touchy subject re: verification of statements.  While not part of this subject, it was brought up by another and in my opinion is not correct.

         "I've never seen a demand for information you have posted to be verified in such a manner."

Actually, any claim made by the gentleman from RPM is indeed subject to verification; by all of those who purchase the various products offered by RPM; both official Yamaha parts and FJ specific items developed specifically for the FJ's.  

Ride safe,

Mike Ramos.

Mike, you are barking up the wrong tree here. It's a poor analogy, and while I can see the connection you are trying to make it's not really relevant in this instance.

Noel

[ribbert]

But what about the running, did the sputtering go away instantly or did it take time to refill the fuel bowls?
Proof; A video would have answered that question.

Noel, I am glad you were able to add your observations, but it still does not answer the question. If your observations answered the question and the video supported your observations, then we could all rest easier know that the mystery had been resolved.

This subject was raised a while back. I said at the time that I believed it was fuel because of the way it behaved, (and I have had plenty of opportunity to observe it) but beyond establishing that to my own satisfaction, I had little interest in the subject until such time as I needed to trouble shoot it.
Nothing has changed.

However, all the ongoing half arsed theories, speculation, anecdotal reports and inconclusive tests did spark enough interest (and that 1% niggle) for me to go and test it. As previously stated, only because it was easy and my bike happened to be low on fuel.

If I thought it would help someone with a problem, and no one else was prepared to do so, I would conduct the test again and video it. If it was something that only required a photo I would have posted it with my findings at the time.
A video showing what I did would be easy. A video proving I was actually doing what you were seeing would be impossible.

It would be an exercise in absurdity to think that I could video all the elements of that test in manner that would prove anything and be beyond the suggestion it was faked to someone already of that mindset.

I have my proof, I shared my findings and my ONLY ongoing interest in the subject is my credibility.

But everyone else says as soon as they switch the reserve switch the bike run fine instantly, at the flip of the switch.

Randy - RPM

I recall a lot of people, especially newbies, mentioning/asking about the lag after they have switched over, as has always been the case with mine. I didn't think there was any dispute about that.

I can determine the feel of the ignition system cut out compared to out of gas, I can't imaging with all of your experience you cannot tell the difference between the two. The rumble/sputtering of the ignition system compared to the carbs being out of fuel. They feel very different, at least to my experience and seat of the pants feel. I can tell you specifically if your are having an ignition problem or fuel problem and I do not need a test light to know.

/quote]

Yes, of course I can tell the difference, as could any mechanic. That is my very point and why I have always been satisfied that it is fuel. However, other people probably have greater confidence in a test light that my arse! My arse had been called many things but never a scientific instrument. I don't believe "seat of the pants" was ever the correct answer in an exam either, hence the test light.

I am sorry that you fell I have questioned your authority, skill level or personal knowledge on this matter, it is not intended to question your ability, but you have posted incomplete finding on the topic and it looks like it struck a nerve; maybe not but it does to me.

I struggle with that one a bit. We are talking a very, very simple procedure here, one that I believe would not have any added credibility even if supported by a video. Determining when there is and when there isn't power to a wire.
Not sure how else I could take that but I will accept in good faith that it was not intended as it read and put it down as another example of things that don't necessarily travel well over the net.

Sometimes you have to take your own advice;

I don't know why you even bought into this.

That's funny. I don't recall saying that and have no idea what it was in reference to but I was having very similar thoughts last night.





BACK TO THE MAIN SUBJECT

I am absolutely dumbfounded at how long this discussion has gone on for.

This has got to be THE easiest thing to settle I've ever come across.

Why don't (and I don't understand why this hasn't happened already) 1 or 5 or 10 or 20 of you just go and test it and post your findings. No shortage of people here that have demonstrated the skills and understanding to do this.  Sufficient numbers of results should negate the need for supporting video evidence too.

Here's an easy one for pump equipped bikes. Take it for a ride without the side cover on and when it starts to splutter put you hand on the pump (after you've pulled over) and feel if it is still working, then flip the switch and feel again.

Or,There is a very good chance your tail light dims with the pulsing of the fuel pump at idle, have a look. Run you bike to reserve and before switching over, pull over and look at the tail light and see if it's stopped, then flick the switch and see if the dimming/pulsing resumes.

Or put a test light on the coils and rest it on the handle bars somewhere while doing the same.

I look forward to a resolution.

Noel

[racerrad8]

Pat, maybe at some point when in the winter months when I have down time with the bikes I could investigate. I am riding my bike daily, my wife and I are riding at least on day of the weekend, and I have more than enough work here at the shop to get back on the road.

I am not sure why anymore investigation or testing is required at this point. There seems to be enough consensus from members who have clearly stated based on the postings within this thread, who have read enough "proof" to close this topic.

Unfortunately, I am not convinced and I do not have the time, want, desire or the technical skill set to allow me to dissect the CDI to see if the fuel system has some form of control of the CDI.

My two 86's bike reserve functions work properly and I am not excited about applying power to my expensive petcocks or disassembling them to investigate either.

I will make my last post on this topic, with the technical information listed in the GYSM, with pictures to support my statements & interpretation.

Here is the ignition circuit with inputs & outputs.

There are two input circuits to the CDI regarding the fuel level and reserve systems and only one output to the fuel pump.

"I" - Fuel censor circuit
"J" - Fuel reserve signal input
"H" - Digital ignitor unit
"P" - Fuel pump driver circuit



Here is the "Fuel pump circuit operation" and fuel pump operation chart.

Now, like I stated earlier I do not have the skill set to understand the schematics, circuitry or this type of electronic knowledge to understand completely how the system is designed to work within the CDI unit. The GYSM does not address the reserve system and based on the chart at the bottom of the page below, the fuel pump runs or does not run at specific input requirements and the fuel pump is not listed as shutting off due to the fuel reserve circuit becoming active.



So, take it for what it is...

               Maybe it works the fuel pump, petcock, CDI, and now something about the tail light bulbs...

Or maybe it doesn't.

I have provided the proof that Yamaha ran the fuel pump through the CDI at not one point but two. For sure, one circuit is the ignition signal for the fuel pump to run "For about 5 seconds when the fuel level is low" when the engine is off. That is the safety feature added in the event of a crash allowing the pump to shut down and not continue to pump fuel which could result in fire.

What is the second circuit that is an input to the CDI: a redundant low fuel warning system or maybe some sort of ignition circuit interrupt?

I have never said they are cutting two cylinders, I have read that several times and I do not believe that to be the case. I think they adjust the "Ignition coil driving circuits" ("Q" & "R" in the top picture) and induce a weak spark to signal the rider. Then when the switch is activated, the coil driver adjusts back to full coil power. The bike does not fall on its nose like the rev limiter that does the same thing, it stumbles & rumbles.

Just have a look at #3 of the ignition system operation...

Take the factual findings and printed interpretation of the information available from the GYSM or the observations that have been posted.

Maybe I'm wrong...but then again maybe I am correct.

Hell, if there is a solenoid in the early petcocks that stops fuel flow, that would have been great information to have known prior and that might have also stopped the fuel flow on Dan Filetti's petcock and maybe saved his bike from burning to the ground.

Sorry, Rich the myth still needs to be proved or disproved...anybody seen bigfoot?


Randy - RPM

P.S. - Harvy, there is no such things as a "turbo fill" circuit of the fuel pump

[movenon]

Thanks for the ignitor layout Randy. Been a good discussion around the digital camp fire. I am sure everyone learned something or at least has something to think about.

A thought, if the ignitor is reducing the spark strength then I am thinking the only way that can happen is to lower the coil primary voltage when you go into reserve mode. I guess a volt meter hooked into that circuit and monitored when it go's into reserve might be a clue. But then again if the RPM drops the alternator voltage would go down..... Oh , well..... And then there are the riders who have installed a relay to get a full 12volts .....

Laying on my back regaining conciseness after parting company with the FJ I think I did see big foot... He had a bottle of wine and mumbled something about "dumb shit".. By the time I got my helmet off he was gone...

George

[racerrad8]

A thought, if the ignitor is reducing the spark strength then I am thinking the only way that can happen is to lower the coil primary voltage when you go into reserve mode. I guess a volt meter hooked into that circuit and monitored when it go's into reserve might be a clue. But then again if the RPM drops the alternator voltage would go down..... Oh , well..... And then there are the riders who have installed a relay to get a full 12volts .....

George

George...stop thinking...

I said I would not post anymore about the aforementioned material, but now George's thought requires explanation on how an ignition coil functions.

The CDI, just like the old cars with points, is an inductive ignition. Current from the battery flows through the thicker primary windings when the switching device (points or CDI magnetic pickups) is closed. This creates a magnetic field that builds strength thanks to the help of the iron core. When the switching device opens (the trigger signal) the flow of current is broken and this magnetic field collapses over to the thousands of secondary windings. During this collapse, the voltage is stepped up, creating the higher voltage that is required to jump the spark plug gap and ignite the air/fuel mixture. This process is called inductance.

The CDI does the same thing electronically as the old breaker point systems did. But, it can adjust the dwell time and control the output voltage of the coil(s) by shortening the electrical flow time (dwell). So, back in the old days of setting the point gap & dwell controlled the amount of electrical flow (dwell) to control the coil output. The CDI can make changes, based on inputs of intake vacuum signal, electrical flow of the reserve function or CDI programming.

The positive 12v side of the coils are not affected by the CDI and the addition of the relay ensures the coils are receiving the full compliment of power to obtain the maximum charge before the CDI breaks the electrical flow and the coil(s) discharge to the plugs.

Randy - RPM