reserve switch

[Pat Conlon]

Like George, I too have enjoyed this discussion. Thanks guys.

[movenon]

     

Have a good week end Randy
George

[Harvy]

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

That statement of mine was tongue in cheek Randy    ...... all good, been an interesting topic.

Cheers
Harvy

[Capn Ron]

Like George, I too have enjoyed this discussion. Thanks guys.

I enjoyed it as well...Learned a few things along the way.  It looks like this discussion solved a problem Nimbus was having over in the "Strange fuel pump issue" thread.  Sweet!   

Cap'n Ron. . .

[FJ_Hooligan]

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


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 didn't think CDI control of the fuel pump was in question.  It's a given for the argument that the fuel pump is turned off for the reserve function.  There only need to be one output to the pump: the wire that activates the pump relay.

The 2 fuel signals make sense: Depending on the position of the reserve switch, the Low Fuel signal may or may not have any affect on the "logic."

With reserve switch in the ON position, the pump gets turned off when the Low Fuel signal activates.
When the CDI sees the reserve switch in the RES position, it turns the pump back on.
OR:
IF the rider ALWAYS leaves the reserve switch on the RES position, the CDI will ignore the Low Fuel signal and the rider will be able empty the tank with no warning whatsoever.  I always choose this option and monitor my mileage using the trip meter.

[ribbert]

So that's it?  Randy declares the topic closed with an open verdict and everyone just drops it?

I would have thought at least one person out there would like their name in lights for being the one that provided "proof" by conducting a simple field test. It would be known for generations to come as "The ........... Solution"

Oh well, I guess some other subject is not far off that will engage us all in lively debate.

I have also learnt a lot from this discussion.......

Noel

[Capn Ron]

Noel,

I tried to test it on my '92...I've got plenty of time to fiddle with such things and enjoy the process.  Really helps me to not only figure it out, but to also remember it years from now when I'm on the side of the road with a fuel delivery issue.  It's more about the "Why?" not just the "What?" for me.

Trouble is...Mine isn't functioning.  Like one of the original posters, mine will just run me out of fuel in the ON position and I have to sort that issue out first.  That being the case, there's not much more I can add.

Cap'n Ron. . .

[ribbert]

Noel,

I tried to test it on my '92...I've got plenty of time to fiddle with such things and enjoy the process.  Really helps me to not only figure it out, but to also remember it years from now when I'm on the side of the road with a fuel delivery issue.  It's more about the "Why?" not just the "What?" for me.

Trouble is...Mine isn't functioning.  Like one of the original posters, mine will just run me out of fuel in the ON position and I have to sort that issue out first.  That being the case, there's not much more I can add.

Cap'n Ron. . .

No worries Cap'n Ron, I appreciate the sentiment.

Noel

[RichBaker]

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


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 didn't think CDI control of the fuel pump was in question.  It's a given for the argument that the fuel pump is turned off for the reserve function.  There only need to be one output to the pump: the wire that activates the pump relay.

The 2 fuel signals make sense: Depending on the position of the reserve switch, the Low Fuel signal may or may not have any affect on the "logic."

With reserve switch in the ON position, the pump gets turned off when the Low Fuel signal activates.
When the CDI sees the reserve switch in the RES position, it turns the pump back on.
OR:
IF the rider ALWAYS leaves the reserve switch on the RES position, the CDI will ignore the Low Fuel signal and the rider will be able empty the tank with no warning whatsoever.  I always choose this option and monitor my mileage using the trip meter.

As I wrote previously, the circuit includes the ignitor because it needs to "know" if the engine is running, so the fuel pump stays energized..... No other reason, there is no circuitry to affect operation of the ignition itself.

[FJ_Hooligan]

Rich,
I agree with your description.  I was trying to explain the logic for the 2 fuel pump wires/signals and the reason the low fuel wire is not redundant.

[yambutt]

te author=ribbert link=topic=9996.msg99508#msg99508 date=1380151496]

My understanding is that the sputtering you get from the engine when you hit the reserve level is the ignition being cut out on two of the cylinders??

I know this is a old subject but I will add this to it...i was riding when my sender unit or whatever it was that caused me to fill like I was running out of gas....looked at my fuel gauge an had half a tank so I switched it to reserve and all was fine....we had stopped a little further down the road to investigate....i had put my reserve switch back to the on position and went to get something to eat...when I got back to the bike and turned it on my fuel pump never clicked a few times to fill the bowls up but as soon as I switched it to RES there went the pump pumping away....since then my fuel pump never turns on with the res switch in the on position so something is cutting the fuel pump off, just not sure what it is...ive looked for bad connections all over the place and even bought a brand new relay but no luck

It has been said categorically here (by someone else thank goodness) that this is a myth. I agree.

If the coils were cutting out there would be an immediate return to normal operation once the switch is flicked. There is not.

I believe it cuts the fuel pump out.

The behaviour of the motor, both when it indicates the need to go to reserve and when the switch is operated is entirely consistant with this. That is, it takes a few seconds to kick back in after it has been flicked. That lag is the time it takes for the bowls to refill.

A motor deprived of fuel or spark has entirely different characteristics and the function of the reserve switch is consistant with fuel starvation, not spark interruption.'

For those that need it proved, it would be a simple test.

Noel
[/quote]

[Ted Schefelbein]

This is one of those topics that I sat and read, and when it was over, I went to the shop and carefully dismantled the reserve switch, cleaned the 30 years of junk off of it, gave it a tiny smear of dielectric grease, tested it with a multi-meter, put it back together, and thanked everyone in my thoughts.

The COVID19 thing is likely leading to some superbly maintained implements.

Thanks again.

Best regards,
Ted