i have a 1985 k10 4wd with dual tanks and my fuel gauge dont work so i bought a aftermarket one and replaced it and it still didnt work so i hooked it up to the sending unit and it started reading over full does anyone know what i can do to get this gauge working the right way thanks

 

The solution really depends on the source of the problem. There is a sending unit in each of the fuel tanks. From there, one wire from each runs to the 'fuel tank selector valve & meter switch' where the signal then travels to the fuel gauge itself (through a few connectors).

Attached you will find a copy of the wiring schematic:

 

thank very much this has been the most help ive had since i bought the truck.....