I've had a problem with my fuel tanks for some time now. While on one tank I've run out of fuel. While parked over night I've had fuel go from the rear tank to the front tank. Today I had the both tanks full and took off for 100 mile drive. I had the tank set on the rear tank but I was using fuel from the front tank. I've replaced the switch valve and the switch on the dash. Neither has helped.

WHAT ELSE CAN IT BE?
Please help with any ideas.

 

Sounds like you have the fuel crossover problem. A check valve in one or both of the fuel delivery modules (fuel pump assemblies) is bad.

The cheaper solution is to add external check valves to both pumps (dealer part only, I think). Otherwise, you're looking at replacing the pumps.

Jason

 

this is a 7.3 diesel. I only have 1 fuel pump and it's a mechanical one mounted on the front pass. side of the block. It has to be something around the switching valve. The new one is doing the samething the old one was doing.

contacts on the plug??????