Dual fuel tank selector

[bikernut]

Can any one tell me if the above Selector Valve has power to it all the time or just for a short bit when you first turn on the key to pressurize the system and then after the engine starts the low oil pressure switch engages and powers it? I have one that seems to do that but I think the selector valve is junk as now the right tank won't work unless I disconnect the left side and jump to the right tank. I also can't find out where it gets it power to work the selector valve.
Can anyone give me a part # for the selector Valve or are they available from a parts store? any one know what they sell for? Do any of you guys have a good wiring diagram that you can copy and send me of this truck with dual tanks, I have purchased 2 books now and the wiring diagrams are junk, don't show much and I would like a more detailed look at the wiring system. thanks in advance for any help!

[MT-2500]

Originally Posted by bikernut

Can any one tell me if the above Selector Valve has power to it all the time or just for a short bit when you first turn on the key to pressurize the system and then after the engine starts the low oil pressure switch engages and powers it? I have one that seems to do that but I think the selector valve is junk as now the right tank won't work unless I disconnect the left side and jump to the right tank. I also can't find out where it gets it power to work the selector valve.
Can anyone give me a part # for the selector Valve or are they available from a parts store? any one know what they sell for? Do any of you guys have a good wiring diagram that you can copy and send me of this truck with dual tanks, I have purchased 2 books now and the wiring diagrams are junk, don't show much and I would like a more detailed look at the wiring system. thanks in advance for any help!

Year make and model and engine and transmission?

[bikernut]

1987 GMC K2500, 350 V/8 turbo 400 tranny

[MT-2500]

Originally Posted by bikernut

1987 GMC K2500, 350 V/8 turbo 400 tranny

The fuel pump relay and fuel pump should run without the oil pressure switch.
The oil pressure switch is a backup for the fuel pump in case of relay fail.

The switch on dash will switch the tank selector valve when pushed and after let off on it does not power anything.

There should be key on power to the switch when key is on but no power out of it when rocker switch is let up.

Also at the same time it is pushed it switches fuel level sender units from tank to tank.

The fuel tank selector valve not only switches to pressure side line of the desired tank but also the return line to the desired tank.

Sometimes when they go bad they will pump fuel out of one tank and return it to the other tank.
Sorry.
The wiring diagrams I have are copy right protected and I can not post them in open forums on the net.
On the wiring diagrams you need a factory repair manual or A All Data online sub.
http://www.alldata.com/products/diy/index.html
And some times Auto Zone web site has some info and wiring on it.
And a lot of public Library’s have online repair car repair info.

As far as parts check you parts stores.
And or GM parts dealer.

[MT-2500]

Sorry about that.
I made a mistake on the fuel tank selector swith switching.

Pink or tan/black fused key on feeds selector switch.

To go to or press left tank the switch puts 12 volts on tan or dark/green wire to run left pump and switch fuel tank selector valve.

To switch to right tank the switch puts 12 volt power to right fuel pump and switch selector valve on the gray or light/green wire.

Good luck

[Bob B]

Hi,
I had a 77 chevy truck with the two tanks and when the valve stopped switching, I finally found that the power to the switch came from the fuse block by the drivers left foot and was just plugged on with an add on connector.
I must have knocked it off when stretching my legs.
BTW this dual tank was a pain to fill both tanks at one stop because of mounting the fillers on different sides.
It is the only one thing that ford did better with the fillers on the same side.
Bob B

[CrazyHorst]

I had the same problem on my '88 Custom Deluxe (R-30).

The RH tank would not work due to the selector valve being inop. Therefore I essentially only had 1 gas tank. I believe the selector is spring-return to the LH side (however can fail in the center position as noted).

If you are getting into that problem my personal advice is to drop both tanks and replace both fuel pumps. If you take the bed off you can do both at once rather easily (and without dropping). The fuel system components are only good for so many years/miles and we are around the 20 year mark.

I also "fixed" the double filler necks by installing a 1-1/2" copper pipe under the bed and across the frame rails. The RH filler neck is now in the LH rear wheel house flare for the dual wheels. Works great especially when hooked to a 25' gooseneck trailer where it would be durn impossible to keep turning it around at gasoline stops.

[bikernut]

very good idea