The Stovebolt Site Forums The Shop Area Interiors Gas gauge vs sending unit testing

My 58 s gas gage reads 1/3 full when full and won’t go higher. I checked and cleaned the terminals on gauge and cleaned terminals on sending unit. I ccheced ground on sending unit and even ran a temporary ground wire from sending unit to body ground. How to I test the gauge. Can I run a hot to one side and ground to other whine in dash to see if needle travels to right ( full side) or another method to rule out gauge before replacing sending unit? Thanks in advice. Everyone here with knowledge and experience is so kind to help us out here. Pete

Pete, does the gauge go down when the tank is empty? If it does then I would say you're sending unit lever arm and float are either getting stuck or not traveling in the full range. It could also be that the sending unit itself isn't registering the proper ohms. I'm inclined to believe that your actual gauge is still working. In my experience, most antique cars gauges still work and it's the sending units or the wiring to and from them that turns out to be the problem.

Pull the sending unit out of the tank and use jumper wires to connect it to the gauge and ground and move the lever manually and see if there are any changes on the instrument panel.