I have a 94 f150 with duel tanks. The pump in the front tank went out, so I just started using the rear tank. I havent really used the rear tank much, just enough to see if it worked well. When the front pump went out the rear was bone dry so I still broke down. I put five gallons of gas in the rear tank and that only lasted about a mile and all the fuel from the rear tank was pumped into the front tank. Any advive would be helpful.

 

your going to have to replace the front pump, the one way valve in it is bad, and it is letting fuel flow into the tank. and if it is bad your going to find that the truck is not going to start unless youturn the key on/off a few times before you actually try to start it because it is going to let the fuel flow back off the motor and drain into the tank.

and before the 87-91 guys jump in here 92-96 truck had a pump in each tank and all the selector valve does is turn one pump off and the other pump on.

in 87-91 the selector valve closed a valve on the fuel line from one tank to the next, because their pump is on the frame rail

 

^ +1. My rear tank doesnt work, but like he said I have an 89 and I just have a fuel pickup pump in my tank, so I can still run it without the other tank. Yours has to be replaced

 

just replaced fuel pump in front tank back pump is good new fuel filter you can crank it when it is cold but have to give gas then it will die and not start back any help would be nice