sixstringer72

dual fuel tanks

make: 1988 ford f-150 300 6cyl 69000 miles

problem: this truck has dual fuel tanks and I am having trouble with either the tanks or the gauge....the gauge when switched to the front tank seems to work fine but when i switch to the rear tank the gauge always reads fuel no matter how much fuel is in tank and i think when switched to the rear tank the fuel is still being used out of the front tank like it isnt switching over at all.

i.e. : i had a half of tank in front ....switched to rear tank(the gauge reading full) drove for 80 miles on rear tank switched to front. gauge then read 1/4 so im not sure if the switch is working at all really. I checked the fuse in the fuse panel under dash(fine)
so i dont know maybe there is a "hidden" fuse or maybe gauge is bad or switch is bad. any help would be great

sixstringer72

Joe_F

There's a fuel selector valve that switches the tanks.

I suggest you get a hold of the system diagram from www.autolibrary.org below or through a paid www.alldata.com subscription (or the factory service manual).

They usually have good diagnostic charts for this type of thing.