1997 F-250 7.3 with dual fuel tanks. A little while ago my fuel gauge went about 1/2 beyond the FULL mark and has stayed there. At first I suspected the sending unit but if that was the case it wouldn't affect both of the tanks (I assume each tank has its own sending unit). Could the actual gauge go bad?

 

It could be. I believe there was a write up on here shortly ago on how to test the gauge itself. I want to say if you ground the gauge out it should peg it on the full side and with the truck off it should be on the empty side but I am not 100% sure. Also just ground it quick to ensure you dont burn the gauge up.

 

I had this happen when I installed a new pump and I thought it was a bad ground. A bad ground will peg the needle. The other thing that could happen is the sending unit arm could pop out of the clip but since its both tanks I doubt that.

 

Check your grounds at the tank. Also check the connector on the top of the tank.