Is there a fuse for the gas gauge in a 1966 Valiant

The sending unit needs to be grounded by way of a ground strap from the sending unit hose neck to the hard line that heads to the engine. It needs to be clean metal, and a nice tight clamp. Most of the time that is the problem, but you can check the guage by grounding the sending unit itself by sticking a test light prong into the sending unit plug and grounding the other end to good ground. If the guage is working, it will go to full, but you don’t need to let it get that far, just ground it and have somebody watch to see if it climbs. If it does, get the sending unit grounded and you should be good to go.