Hey guys and gals need some help on this one. I was leaving my buddy's shop the other day and noticed that my front tank was at 1/4 of a tank so I switched over to the rear tank since I like to keep at least a 1/4 of a tank just incase. I had to run to the store to get some stuff ran in and got what I needed came out and started the truck and noticed that the rear tank was at a 1/2 and not moving. I know it was full when I parked it. switched the tank to the front and it moved a little bit. you can take the tank switch and move it back and forth and the gauge will move a little bit. went home and parked it and the next morning got in it and it was still on the rear tank well the fuel gauge decide it wanted to go to a 1/4 of a tank and a 1/2 on the front I am lost and am ready to replace the fuel tank transfer valve since that's where the signal is coming from. besides the floats in the tank. any help would be appreciated before I have to spend 300 on the valve.

 

sounds like that would be the cheapest swap to find the problem. when you have to drop tanks to swap out floats is when you start cussing and swearing a bit more then normal.
let us know how the swap goes. i hope you nailed the issue and it fixed it.

 

still working on this problem filled the truck the other day and the gauge was reading on front and rear tank. had it on the front tank it was reading and the gauge was moving as i was driving but when i switched it from front to rear the rear gauge showed 3/4 of a tank and the front showed full. i tested the valve and you can hear it switches. the only think is either A. The gauge is off or B. the switch on the dash is bad but it is switches the valve to move between the front and rear tank i do have a new/used tank selector valve that i am going to try but if the one on the truck is switches from what i can hear. there are several other tests left to try. ill keep everyone updated.

 

problem solved it ended up being the selector valve. got on off a truck from the junk yard for 2 dollars vs 700 from ford