Hi, just bought a 1995 f150 supercab with duel fuel tanks. My problem is with the truck running,using the front tank, I switch to the rear tank and the truck stalls. Is this a bad fuel pump or is there a relay or transfer switch somewhere? Thanks in advance, this is my 1st ford truck. The fuel gauge does work on the rear tank.

 

There's no "real" selector valve on these trucks. (1992-1996 only) The older 1987-1991 and 1986 5.0L EFI trucks have a dual function reservoir mounted on the frame rail that acts like a selector valve. The Carburated trucks 1985 and earlier 5.0L and 1987 and below 4.9L, 5.8L and 7.5L have a 6-way mechanical valve. But anyway, the switch on your dash selects which fuel pump will be energized. There's a 1-way valve on the FDM (Fuel Delivery Module, fancy schmancy word for in-tank fuel pump.) that keeps the fuel from the energized pump from transfering fuel to the other fuel tank and that only allows unused fuel from the engine to drain back only to the tank from which is was pumped. (in other words, from the tank whose FDM is energized). So, either it's a bad relay or a bad FDM. These stupid things are immersed in gasoline and that's what cools down the pump motor. If you let the tank run really low, there's a chance the FDM will burn up. Nice, huh?

 

Thanks for the help n578md! Is the relay under the hood ? It sound like this would be the easiest thing to check for 1st. Thanks again!

 

From my 1996 manual: Relay 2 and fuse 16 on the Power Distribution Box under the hood control the fuel pumps. I guess if either of these were bad, neither of your tanks would work. When you switch the selector to REAR, do you hear the fuel pump?

 

I went out and tried to listen by myself and couldn't hear the rear or the front pump running. Everyone else in the house is asleep.

 

Better not wake up the wife, that could cost!! When you turn the key to "run" without starting the engine, the fuel pump should come on for 2 to 3 seconds if I remember correctly so you will need someone to help.

 

I'll do that tomorrow when my wife's eyes are open. Thanks again for your help.

Gary