1950 Hudson gas guage

Did the gauge work correctly before? It sounds as if the unit when back upside down. Try making a good ground from the sender to the frame( better, the pos post on the battery, if + ground). If no luck with grounding the sender, take the sender wire off and ground it for a moment with the ignition switch on. This should cause the pointer to peg to full. You may need a helper to watch.If the pointer does move, your problem is likley in the sender, or ground of the sender itself.If no movement a break in continuity or gauge may be the cause. If the gauge moves, take the sender out, reconnect the wire, turn ign on and move the sender float arm to see what the gauge shows. If moving the arm shows corresponding gauge movement your ok and an adjustment is needed. But no gauge movement shows a bad sender. The sender is a variable resistor... it varies on the angle of the arm within a range. Gauges are usually not the cause. If you need a new sender I believe Paul Shuster sells the correct ones.

Thanks for the heads up, Geoff. I think I did that once before ie, thinking the 50s were resisted. So odds are that he replaced the unit in upside down?