Fuel Gauge Tank Selector switch and valve

1984 K10 - two new tanks. Two new fuel sending units. One is an ac delco the other is from LMC. Ground from battery to frame and then to sending unit is good.

Fuel gauge is stuck at 9:00.

Fuel selector valve moves between the two tanks but doesn’t run correct on the passenger side as it will only idle and drive around slow - any throttle demand and it dies. Assuming I should replace selector switch first and then possibly the selector valve?

Can the switch and or valve cause my fuel gauge issue? The pink/black stripe wire is not carrying any resistance up to the gauge.

Fuel gauge at 9 all the time or only with passenger tank?

danzey said:

The pink/black stripe wire is not carrying any resistance up to the gauge.

Click to expand...

Usually PNK/BLK goes to valve (from passenger tank sender) and from valve the PNK goes to gauge.

edited to include wiring diagram-just in case.

Thanks. Yea I meant all pink. The fuel gauge is at 9:00 all the time with either tank selected.

I feel like the sending wires in the tank valve are not connecting to the pink wire. Can you pull the plug and jump a green wire from tank sending unit to the pink wire running up to the dash to see?

>>>> Can the switch and or valve cause my fuel gauge issue?

Not the Switch I dont think, but the valve... Yes. The Valve has the contacts in it for the sender selection. I did two new tanks as well, and I thought I was out of luck getting the gauge to work. But, I switched the tank valve back and forth a dozen times, listening for the moto in the valve to run. And, my gauges started working ! I think the contacts in the valve were dirty and moving them in and out, they must have cleaned up. Now I switch between tanks every fill up to keep things moving.

If they were not going to clean up, I probably would have run the two tank sender wires up front and put in a temporary switch that would feed the pink wire until I could save up for a new valve.

I had nothing but problems when I first got my K20 dual tank.
Bad wiring was first- wires everywhere. Bad ground. Finally said to hell with it and did two new tanks, two new sending units and all new wiring. Kaching$. but she works now

danzey said:

Can you pull the plug and jump a green wire from tank sending unit to the pink wire running up to the dash to see?

Click to expand...

PNK/BLK or PNK/WHT (depending which tank you are checking) could be jumped directly to the PNK wire.

The sender controls the current going to ground. The more current going to ground the more the gauge heads towards “Empty”. Unplugging the PNK wire completely should send the gauge past full (3 o’clock)

Here is a good video explaining how to diagnose a gauge
LINK - fuel gauge diagnose

Gauge stuck at 9 o'clock means you have an open circuit, so something isn't connected/broken wire/etc.

I fought mine for a while before finding it was a bad dash selector switch.

I jumped the two tank wires over to the pink one at a time and the gauge read full (both tanks are full)

So the sending units have ground and are working. I’m going to put a new switch and tank valve in and hopefully that fixes the problem.

I ended up putting in a new switch just to eliminate that possibility. I chose to put in a 1987 switch that isn’t momentary. I also installed a new fuel valve and bingo the problem is fixed. Now the biggest challenge will be how to get the heat shield back in place to protect the new valve from the exhaust heat.

Sounds like alot of work. I have to dig into passenger, aux tank and figure out why that side causes it to die. I was thinking fuel pump, but guess I should ck voltage of wires at valve 1st. Not looking forward to it.
Good job.

I just replaced the valve and switch for my 86 k10. Both tanks new and new sending units. All is now working perfect.

The problem - after replacing the valve I have a slight hesitation at 1600 rpm that wasn’t there before. I have a new fuel filter in place.

Any help would be appreciated.