Hi everyone I have a rather annoying problem I have a 1988 f150 with a 4.9L I6. I just finished rebuilding the engine and well that is where the problem began. The truck will start without a hickup idles great (around 800rpm) however after 45 to 50 seconds of idling the gas gauge drops and the truck stalls out like it is out of gas.... I recently replaced the sending unit in the rear tank (I have dual tanks) and the tank is full...But after it idles for a few it almost seems like it is switching tanks (the side tank doesnt work hasnt for atleast 15 years...). I am totally confused an looking for help any advice?

 

Sounds like a problem with the switch valve it is pretty common. I just disabled tank 2 routing all fuel lines to the main tank and disabling the switch valve and dash switch. Those do act up and it seems like that is you problem. I think a search on tank switch or something of that nature will land you some fixes that have been posted many times.......

 

thanks for the post ill check around see If i have any luck.