I have had my 98 for over a year and my fuel gauge has never worked. My cluster is not the issue. While attempting to diagnose it, it seems as though there is no power running to the sending unit. Is this the first avenue to address? I have the tech manuals for the truck but cannot find a wiring diagram.

 

On top of the tank are the wires, the thicker ones are for the pump the thin ones are the sending unit. Honestly though if its the original pump sending unit itself may be shot. A lot of times this is a precursor to the pump failing soon.

 

we tested the sending unit by pulling it out, putting resisters on it, and moving the arm. It came up with the appropriate amount of ohms, so we assumed it wasnt a bad semder