I have an 89 F150 6 cylinder. I drove to the gas station and the front fuel tank was working fine. I filled the front tank with gas leaving the rear tank nearly empty. Then after running on the front tank for about two minutes the engine cut off. I switched to the rear tank and the engine restarted. Apparently fuel flow was restored. I repeatedly switched to the front tank form the rear and the engine stalled every time after about two minutes. The fuel guage changes to indicate the respective fuel amounts when I switch tanks. Did the front tank pump just coincidentally die after refueling or could it be something else?

 

It could be your selector valve going bad. The FORD selector valve uses a +12vdcmotor toswitch to the rear tank with a SPRING return to normal for the front tank. It could be that the spring is getting week. If it is in fact failing, I would replace the selector valve with a POLLAK valve. These use +12 vdc motors in both direction for a positive switch.