Hey Guys, I need your help....is it possible for a 1991 F150 I6 dual fuel tanks, for the rear tank to pump into the front tank....the front gauge doesnt work but either the rear tank is pumping into the front tank or I have a neighbor stealing my gas....

If this is possible,,,will it make the truck run with throttle hesitation of idle poorly....any advide is greatly appreicated...

Jimmy

 

The pumps transferring is a common problem. Do a search in this forum for "shuttle valve". If you're pumping into the front tank, the shuttle valve in the front fuel delivery module is FUBAR. Changing the module will also get you a new level sending unit

 

I finally got one I could crack open, and I was surprised to find it wasn't actually the shuttle valve causing the fuel transfer. In this particular case, it was the diaphragm that isolates the shuttle valve from the hi-pressure side. Based on what I've seen with other crossflowing FDMs, I'd bet this is much more common than a stuck valve.

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Either way: yes, it's common for them to transfer fuel, and eventually the receiving tank can overflow. You can buy an FDM without a level sender, and every "bad" sender I've taken apart was repairable.

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Even leaking floats are easy to repair with a common soldering iron.

 

Thanks for the tips,,,,,for a while there I thought I was going crazy...lol. Put half a tank in the rear tank and 20 miles later it was empty....thanks again...

 

i had a 95 that would do that if u used the front tank to 1/8th tank switched to the rear by the time the rear was 1/8th tank if u switched back to the front u had 1/2 tank in the front