Fuel selector valve leak-by

[Prowler901]

Howdy folks,

I think my fuel selector valve is not working properly. It appears that both of my tanks are being used at the same time. Anyone else seen this before? Can it be corrected, or is it just a valve replacement scenario?

Thanks,
Todd

 

[1987 GMC Jimmy]

Yeah, that’s absolutely plausible. If a contaminant wedges itself in there, that’s what happens. I don’t know of a disassembly procedure. Maybe you can try backflushing gasoline through the outlets using some kind of gentle pressurizing mechanism like a syringe. I don’t know if that’ll work, though. Maybe someone else has an off the record fix for you. Otherwise, prepare to replace.

 

[Prowler901]

Hi Jesse. Thanks for you input. I may look in to flushing it. New valves are about $50, so that's not too bad either.


Regards,
Todd

 

[75gmck25]

New three port valves are fairly easy to find, but the 6 port pollack valve is a different story. Do you have a good source for the 6 port valves?

Bruce

 

[Prowler901]

Hi Bruce,
LMC and Rockauto both have the 6 port valves available.

Todd

 

[flying2275]

Hi Jesse. Thanks for you input. I may look in to flushing it. New valves are about $50, so that's not too bad either.


Regards,
Todd

Hi Bruce,
LMC and Rockauto both have the 6 port valves available.

Todd

Those are NOT the correct one wire 6 port valves like your truck should have. They can be made to work but will require electrical modifications.

If it looks like this its NOT the right one.

You must be registered for see images attach

Your 79' should look like this.

You must be registered for see images attach

 

[75gmck25]

You are right about the fitment. My six port fuel valve has one terminal for 12 volts, while the ones sold by Rock Auto have the muli-terminal plug.

I've seen those muli-wire fuel solenoids, but don't know how the electric part works.

Bruce

 

[chengny]

Howdy folks,

I think my fuel selector valve is not working properly. It appears that both of my tanks are being used at the same time. Anyone else seen this before? Can it be corrected, or is it just a valve replacement scenario?

Thanks,
Todd

That style of transfer valve is solenoid operated and is controlled by only a single lead. The dash mounted switch is a rocker type (as opposed to later versions which are of the momentary style).

When the switch is toggled from tank to tank, it stays where you left it - until you toggle it again. Depending on position, the solenoid in the transfer valve either receives 0 or 12 volts from the switch.

With no current applied to the solenoid coil, the valve shifts - by internal spring pressure - to the production (RH) tank. Only when full battery voltage is applied to the coil will the valve move to the auxiliary tank. The ground leg for the coil is though the valve body - and then into the frame.

This design should not cause any issue (in the case of loss of control power/continuity to ground) - if you wanted to pull from the default (production) tank. But, if a low voltage/poor ground condition exists, it would likely prevent the valve from shifting fully over to the auxiliary tank.

Move the dash switch to the main tank position and verify zero voltage to the coil on the LT GRN control wire.

Then move the switch to the AUX position and verify 12 VDC to the coil on the LT GRN.

If both those tests look good, clean/tighten the valve mounting - ground path - to the frame.

As the control switch is toggled between the tanks, the valve should produce an audible snap which would indicate that the valve is shuttling as designed.

You must be registered for see images attach

 

[Prowler901]

Thanks for the details, Chengny. I'll test all that and see what happens.

 

[1980 Big Ten]

Thanks for the details, Chengny. I'll test all that and see what happens.

Ditto, Chengny—thanks. I’m having a similar problem on an ‘80 C10. Truck runs fine on the RH tank, and idles fine on the LH tank, but I don’t have to drive very far down the road on the LH tank before the truck acts like it has run out of gas. Both tanks and accessories were recently replaced, so I’m guessing either the previous guy didn’t install them correctly or used cheap parts.


Sent from my iPad using Tapatalk