reserve switch

[racerrad8]

Hmmm, by looking at his wiring diagram the "reserve" switch is not part of the fuel pump system, it is part of the CDI.

ETA: Looks like Noel just proved it's a FUEL-cut, not spark, for the pump-equipped models...

What proof...?

I see no video of the running bike showing the stated results.

I am awaiting proof.

Randy - RPM

[Flynt]

My read of this is wire "G" provides output of the low fuel thermal sender to cdi.  The "Reserve Switch" restores power to the "Fuel Pump" relay, closing the switch and powering the pump.  The only thing that's not clear is how the fuel pump relay is powered when the reserve switch is open and G says there's enough fuel, but I'd bet the normal signal on G causes cdi to close the relay with the other wire out of the top of the cdi going hot, the one with the writing by it.

In other words, it is cutting the fuel pump relay it looks like.  But notice that the cdi is also controlling the coils...  maybe it cuts spark and fuel, then you restore normal ops pretty quickly by flipping the reserve switch.  If you don't flip the switch, you'll run the bowls dry on 2 cyl and it should die.

There's a test for you guys with working reserve switches...

Frank

[movenon]

The other half of the drawing explains more. The top 2 wires going off to the left, one from the relay coil and the R/W line go on past the engine kill switch and merge as one wire going to the ignition fuse. The kill switch is in the bottom line.
The diagram is in the 1991 FJ 1200 Service Guide.

Just a curious note. I keep seeing a pattern. Any wire with Green "G" on it has to do with the fuel circuit, any wire that has Blue "L" on it is a control line. Any wire with Red "R" in it carry's B+, Gray "Gy" signal line,  and Black of course is usually ground.

Then there seems to be a priority order of things.
Red  
Red / White
Brown / Red
Red / Yellow

note the fuel reserve switch is R/G,  red for b+ and green for fuel related. Trivia...

I see a few deviations of this but in general the above seems to be true.

Frank, you might be correct on both happening.    More testing required.  I am still in the fuel cut off only camp. I just do not believe Yamaha made it all that complicated. When it comes to what really happens in the CDI units all the manufactures keep that a big secret. They will not even tell you the theory of operation or pin read outs.

I uploaded the 91 Service Guide into rapidshare.com  https://rapidshare.com/home You can log in as  name: movenon    and download it.
                                                                                                                                        Password: fjowner
George

[Capn Ron]

I drained out all but about 1/2 gallon of fuel to try and back Noel up on this one...The fuel was well below that sensor and with the tank switch in the "ON" position, the bike just keeps running.  I suspect that I don't really have a working reserve warning system, so It looks like I'm out of this debate.  At least as far as absolute testing results are concerned.

To me, the reserve switch in the schematic looks like it just has a hot lead and is normally open, when you close the circuit, it just sends a + voltage signal into the ignitor.  That  ignitor is an amalgam of circuits, IC chips, and a pile of If-then-else logic (Randy is familiar with how I know that   ).  I'd be hard pressed to know what that signal does to any down-the-line outputs from the ignitor.  It may very well cut the voltage to the fuel pump (on models so equipped)...it may *also* cause a misfire as reported in magazine articles early on.

I REALLY wish mine functioned as it's supposed to, because, as Noel suggests, I'd have the answer in 10 minutes.

To answer your question Noel as to why folks are making such a meal of this (I loved that)...I tore my bike apart to solve a starting issue when I was on my trip, 3,000 miles from home.  I began at one end of the bike testing each function as I understood them to work and ended up at the other three days later.  I cleaned wires/connectors, replaced switches, installed relays in an effort to troubleshoot the problem.  Understanding...REALLY understanding how a system works makes troubleshooting that system a snap.  At least that's my excuse for wanting to know.  

Cap'n Ron. . .

[movenon]

In another thread about water and FJ's I was thinking that the fuel reserve switch doesn't appear to be real water proof and is in a vulnerable position.

On my bike with the new fairing there looks to be a small "leak" point around the front turn signal buckets. An entry point for water in a rain storm. I might be missing a seal there ? It's on my list of things to investagate....
George

[RichBaker]

My read of this is wire "G" provides output of the low fuel thermal sender to cdi.  The "Reserve Switch" restores power to the "Fuel Pump" relay, closing the switch and powering the pump.  The only thing that's not clear is how the fuel pump relay is powered when the reserve switch is open and G says there's enough fuel, but I'd bet the normal signal on G causes cdi to close the relay with the other wire out of the top of the cdi going hot, the one with the writing by it.

In other words, it is cutting the fuel pump relay it looks like.  But notice that the cdi is also controlling the coils...  maybe it cuts spark and fuel, then you restore normal ops pretty quickly by flipping the reserve switch.  If you don't flip the switch, you'll run the bowls dry on 2 cyl and it should die.

There's a test for you guys with working reserve switches...

Frank

It goes thru the ignitor because it has to see the engine running for the fuel pump to keep pumping.... If no "engine running" signal, the fuel pump shuts off after 5 seconds.

per Noel's post above:  "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

I'd say that's proof.....

[Capn Ron]

In another thread about water and FJ's I was thinking that the fuel reserve switch doesn't appear to be real water proof and is in a vulnerable position.

On my bike with the new fairing there looks to be a small "leak" point around the front turn signal buckets. An entry point for water in a rain storm. I might be missing a seal there ? It's on my list of things to investagate....
George

Oh, yeah...water will find it's way into about anywhere and that rocker switch is no exception.  Thing is, 12V DC isn't going to do any harm to a switch when water is introduced or cause a connection to be made.  You can drop + and - battery leads into a glass of water and you won't see even a .01V drop on the battery.  Turns out at the low voltages we're dealing with, water is a terrible conductor.  Don't take the same chance with 400 amp, 408V AC mains!!

The bigger issue is corrosion and there's where water will slowly...quietly...corrode your contacts in the background to the point where they have a very high resistance to conducting currrent.  That resistance can cause heat...arcing...and more corrosion.  Eventually, the corrosion is an insulator and the switch no longer works.

Don't get me started on battling salt water corrosion on the sailboat!  

Cap'n Ron. . .

[Harvy]

OK......I'm of 2 minds now - mainly due to not knowing what goes on in the Ignitor box (which is no longer even a consideration on my bike seeing as its no longer connected to the loom).
Looking at the coloured wiring diagram for FJ1200B ('91) included in my Yamaha Service manual, the Green/Red stripe wire comes from the fuel level sensor and goes to 3 locations - the lowfuel light, the Relay assembly and the Digital Ignitor Unit.

Fuel pump power is a blue/black stripe wire from the relay assembly

Reserve switch has 2 wires - a Red/blue stripe which goes to the Digital Ignitor, and a Red/Black stripe which goes to 3 places - the Engine Stop switch, the Relay Assembly and the Digital Ignitor.

In all of the above, - any wire going to the ignitor no longer comes into the equation.

Now on my bike, If I leave the reserve switch in the normal on position, the fuel pump does not run - period, and if i switch from the Res position to the On position while riding, it will run until the bowls are low on fuel and then start to splutter. Switch it to the Res position and it will return to full power within 10 seconds or so (not instantaneous) ...... that's why I think the reserve switch acts on the fuel pump, not the ignition. If the Ignitor box was still in the circuit, then it could be a timed ignition shutdown, but its not!

That's my take on it.

Harvy

[ribbert]

What proof...?

I see no video of the running bike showing the stated results.

I am awaiting proof.

Randy - RPM

You'll be waiting a while, there won't be one. I conducted that test for my benefit because while confident of the outcome it removed that niggling 1%, and then, only because it was easy. If my bike had more fuel in it I wouldn't have even bothered.

I only posted my findings because of all the speculation that was going on and thought it might be of interest. People can draw their own conclusions from those findings.   I didn't make any claims, I simply posted my observations. There is nothing for me to prove.


My views on mechanical issues and procedures are not always embraced here. If some wish to dismiss it on the basis that it came from me, fine. If they think I skipped the lesson at trade school on how  to tell if a test light is glowing or not, fine. If they choose to suggest it didn't happen, not so fine.

You want proof? you'll have to look elsewhere. It's a bit sad If you are only prepared to believe what I say if it is corroborated by video. After all, we are only talking about a test light going on and off.
I've never seen a demand for information you have posted to be verified in such a manner.

Noel

[skymasteres]

Well gee whiz. I'm glad I'm not the only one that gets this neurotic about this stuff.
I'll do my own investigation, but looking at the wiring diagram I'd say it's pretty conclusive that it's the pump that's getting de-energized.

Looking at that I'd say it would be pretty cool to measure what the value of the resistor north of the tank sensor is.  You could add a pot and adjust where your reserve is.
If you're like me and find yourself often 60+miles from a fuel depot then it's a nice idea. On the same note, characterizing the fuel level sensor would be nice to see if it's possible to add resistance to calibrate it into a more useful range. (Or if it uses discrete components change a resistor)

Cool stuff...

[The General]

mmmm...I wouldn`t call it thermal sensing.....This might help explain: How Capacitive Liquid Level Sensors Work

[FJscott]

Looks to me to be a reed switch. They are commonly used in hazzardous and explosive environments...gas tanks.

Scott

[racerrad8]

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

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.

No video, that's fine I am confident in your ability to see if your test light illuminates or not and the understanding of electrical function. But the fact remains, the reserve switch does not appear to function solely within the fuel system.

The reason a video would be nice so that it could be "proved" that the fuel pump does not run, the engine is stumbling and as soon as you switch the switch the engine runs fine or not. As I posted earlier in the thread, how does the fuel pump fill the carbs "instantly" to allow the engine to run fine?

Heck, even Harvy has posted that it takes 10 seconds for his engine to start running properly when low on fuel as he does not use the stock CDI and does not have the ignition cut out circuit.

...Switch it to the Res position and it will return to full power within 10 seconds or so (not instantaneous)...

Harvy

So, that means it has to fill the carbs up for it to run properly when the stock CDI is removed from the equation. But everyone else says as soon as they switch the reserve switch the bike run fine instantly, at the flip of the switch.

Maybe I am confused, maybe something has been lost in the translation of language.  

Doesn't that mean the CDI box is affecting the spark cycle somehow and cutting out the fuel pump?
When the switch is activated, the CDI then allows full spark and the fuel re-energizes filling the carbs again?

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.

I conducted that test for my benefit because while confident of the outcome it removed that niggling 1%, and then, only because it was easy.

I only posted my findings because of all the speculation that was going on and thought it might be of interest. People can draw their own conclusions from those findings.   I didn't make any claims, I simply posted my observations. There is nothing for me to prove.

My views on mechanical issues and procedures are not always embraced here. If some wish to dismiss it on the basis that it came from me, fine. If they think I skipped the lesson at trade school on how  to tell if a test light is glowing or not, fine. If they choose to suggest it didn't happen, not so fine.

You want proof? you'll have to look elsewhere. It's a bit sad If you are only prepared to believe what I say if it is corroborated by video. After all, we are only talking about a test light going on and off.
I've never seen a demand for information you have posted to be verified in such a manner.

Noel

I am not going to be awaiting your proof, as you are not offering it. But, just like you questioned my comments earlier about the system working in the CDI as there is not enough time for the carbs to refill and you cannot understand how 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.

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.

Sometimes you have to take your own advice;

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

And:

If the extent of what has been said is what was posted this morning, I can't possibly see what your pissed at.

I am not demanding proof of your findings, do what you want, but proof will support your position when you make your observations as you posted them to end the speculation.

So, the question still remains...

CDI interrupt?
Fuel Pump interrupt?

Or a combination of both?

Based on Noel's observations, it seems part of the question has been answered; thank you Noel.

But as far as the rest of the question, as I stated earlier...

All you have to do is bring the tech and prove it to me otherwise.

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

Randy - RPM

[FJ_Hooligan]

I would explain this with my previous observation.  In typical cruising, starving the idle circuit will cause noticeable stumbling.  I think a possible explanation is when someone feels that stumble and flips the reserve switch (assuming it is working ocrrectly), they then roll back into the throttle and start getting fuel from the main jet and needle circuit which would appear to be an instantaneous fix.  In this case, the fuel pump would catch up unnoticed.

[racerrad8]

I would explain this with my previous observation.  In typical cruising, starving the idle circuit will cause noticeable stumbling.  I think a possible explanation is when someone feels that stumble and flips the reserve switch (assuming it is working ocrrectly), they then roll back into the throttle and start getting fuel from the main jet and needle circuit which would appear to be an instanteous fix.  In this case, the fuel pump would catch up unnoticed.

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.

Randy - RPM