dual gas tank troubles

[staggerd86c-10]

well im trying to figure out what is wrong with my dual tank setup in my truck. I put a new switch, selector valve and i put an electric fuel pump so when i switch the tanks it should have fuel pressure even though the truck is not on. when i have it on the passenger tank it has pressure, as soon as i switch it over it drops all the way down to 0. What do you guys think is wrong with this thing. I would like to have 2 gas doors for a reason and not eliminate the 2 tanks and just put one.

[glock35ipsc]

Is the electric pump the only pump supplying the engine?

And how is the pump powered? How did you wire it to power? Is it running when it's switched to the pass side, and does it completely stop running when it is switched to the drivers side?

[knightowl73]

is your pump on the frame? if so, you might just need to prime the line once so it is full of fuel, then if the tank has gas it should pick it right up. can you hook up a pump to the line right before the selector valve and suck gas thru? thinkin maybe a cracked rubber line somewhere in between the selector and the tank.

if you are running electric in-tank pumps and the first one works, you might want to check wiring diagrams in the haynes and see what switches power to each fuel pump. could be the second pump is not getting the power switched over when the selector does.

i am not familiar with the set-up, just my diagnostic brain hard at work, hope this helps.

[datguysaL]

If u have the in-tank pumps, then most of the times you should be able to hear it from whichever tank u select. Give that a try.

[mckirk88]

I have about the same problem. I have dual tanks on my 86 Scottsdale and the selector switch doesn't work evidently because the passenger side tank is full of fuel and won't switch. Could there be anymore problems besides the switch?

[69BBsuburban]

Have you pulled the tanks to check the lines? The line on the tank not supplying fuel could be rotten, or broken inside tank, causing an airleak, so the fuel pump will just suck air.

[mckirk88]

The lines are all new. That was my first replacement. I'm hoping its just a bad switch.

[staggerd86c-10]

well now that i got my cluster done my gas guage works and my drivers tank is full but it will not get gas. as soon as i switch the tanks the fuel pressure just drops.

[69BBsuburban]

Originally Posted by mckirk88

The lines are all new. That was my first replacement. I'm hoping its just a bad switch.

Sorry, I was referring to the original poster.

Originally Posted by staggerd86c-10

well now that i got my cluster done my gas guage works and my drivers tank is full but it will not get gas. as soon as i switch the tanks the fuel pressure just drops.

Is there any fuel in the other tank? If the tank valve has a small, internal leak, it can suck air through the valve from the tank that is empty....