Dual Tank Switch Problem

[TropicalSilverado]

I gassed up my '87 R10 today only to find later that the dual tank switch won't go to the right (passenger side) tank. The engine died as soon as I switched over to the right tank so I switched it back to the left and the truck re-started. Never had this happen before and I have switched sides often. No bad fuses so could it be the switch has finally given up? Thanks in advance for any suggestions.

 

[sgrinavi]

If it died when you pressed the switch it's probably the valve or an obstruction between the RH tank and the valve.

 

[TropicalSilverado]

What has me puzzled is that the switch worked fine earlier the day I gassed up. Maybe having more gas in the tank than I usually have triggered the problem. I changed out the switch and checked a few of the fuses but nothing.

 

[CalSgt]

I gassed up my '87 R10 today only to find later that the dual tank switch won't go to the right (passenger side) tank. The engine died as soon as I switched over to the right tank so I switched it back to the left and the truck re-started. Never had this happen before and I have switched sides often. No bad fuses so could it be the switch has finally given up? Thanks in advance for any suggestions.

If it died when you pressed the switch it's probably the valve or an obstruction between the RH tank and the valve.

I believe '87 should have in tank electric fuel pumps too, you could have a pump going bad.

 

[TropicalSilverado]

Thanks for your suggestions. I’ll be trying to eliminate these possible causes as I can and let you know if I find the culprit.

 

[chevytech87]

What has me puzzled is that the switch worked fine earlier the day I gassed up. Maybe having more gas in the tank than I usually have triggered the problem. I changed out the switch and checked a few of the fuses but nothing.

Does your fuel gauge work? If it does I’d agree on it likely being an in tank pump issue.

 

[SquareRoot]

The gauge has a separate circuit inside the switching valve. It's possible to have one go bad independent of the other.

 

[TropicalSilverado]

No, my fuel gauge is not working as it should. The left tank shows nothing and the right tank shows 3/4 full. After flipping the tank selector switch with the ignition off and back on, the gauge pegged full in the right tank. I've read somewhere here that's an indication of something but can't remember what. Also saw somewhere earlier that if the tank selector switch has no power, the right tank is the default tank and continues to get fuel. Is that correct?

 

[TropicalSilverado]

No, my fuel gauge is not working as it should. The left tank shows nothing and the right tank shows 3/4 full. After flipping the tank selector switch with the ignition off and back on, the gauge pegged full in the right tank. I've read somewhere here that's an indication of something but can't remember what. Also saw somewhere earlier that if the tank selector switch has no power, the right tank is the default tank and continues to get fuel. Is that correct?

Also, what fuse would possibly be a part of this ongoing problem? Thanks again for any and all suggestions.

 

[Dmack]

Usually, the gauge pegged past full is an indicator of an open circuit.

 

[chevytech87]

My truck did something similar when my valve gave up. There is an ECM fuse that was open as well post repairs. I’d check your fuses, and power at the valve connector. Short answer on the default tank question is I think so? However if the valve is stuck in the middle as mine was…. No fuel at all.

 

[gogo14910]

I just replaced everything and mine is acting similar. I’m new to all this. I heard things like pump ran dry and failed, pinched hose, etc. I told my welder son all this and he asked, “did you use flux when you soldiered it?“ …uuuhhhh, what is flux? So now I have to redo the wires, and i was so damn proud of myself.

 

[Snoots]

Go here, Post #4.

Dual tank wiring

Why is the tan fuel gauge wire that runs up the right frame rail routed so long? Its gotta be near 20 feet of wire! 1976 C20 dual tanks. It runs from the firewall down the left frame rail then across to the right frame rail, then forward to the starter heat guard tube, then back behind the...

www.gmsquarebody.com

Also, there is a 2-wire connector on the firewall near the acceleerator cable. Check that for bad/good connection.

And there's this . . .

xc_hide_links_from_guests_guests_error_hide_media

 

[TropicalSilverado]

Can anyone tell me if there is an inline fuse or possibly one in the fuse panel that is related to the tank selector switch? Thanks.

 

[dusterdude]

I would like to know that too