I have two gas tanks and when I switch to the front tank it stop running. and I switch it back to the back tank it starts running. Is it the pump or relay switch?

Sounds like something amis in the tank,like pump coming out of the fuel, check the pick up filter screen.

If you front tank is low. The fuel pump isn't getting the gas it needs. Don't run the front tank down to nothing.

Local library.

in tank sock filter could be plugged up

the electric fuel pump is defective in the rear tank, each tank has its own pump

the problem is the fuel pump inside the front tank is defective, it is not a fuel filter, the fuel from both tanks fuel pumps runs through the same filter

If the gauge works on the rear tank but not the front, the problem is most likely the sending unit in the front tank. You will have to drop the tank to change it. I guess what I would do is, set your trip meter to zero when you fill the front tank. Then, run that tank to the point where the truck is starting to run out of gas and then switch to rear tank. Keep track of how far you can go on the front tank. Then when you refill the front tank reset the trip meter and switch tanks about 20 miles before you think it's going to run out. It's not a good idea to run those pumps dry. Just make sure you have gas in the rear tank. If you do decide to change the sending unit, run that front tank as empty as you can, also, I would change the pump too. In 92, I think the pump or the sending unit can be replaced seperately. The worst thing about changing those in tank fuel pumps is getting the gas out of the tank. No trip meter? Just write down the mileage from the odometer. Good luck.

check all lines and filters. berrydalewolf

There is no selector valve on a 1995 ford f150 300 engine. The selector switch on the dash sends power to the pump in the selected tank. The pump then sends fuel to the engine. If engine won't run on the selected switch, the pump in that tank needs replaced.

Have the same problem, its the switch valve, not sure how to fix it yet. But i can tell you thats what it is.