The Stovebolt Site Forums The Shop Area The Electrical Bay Gas gauge gone crazy

My '59 gas gauge reads Full all the time if the key is on. (Goes to E with the key off.) I tried disconnecting the wire at the top of the sending unit and it still reads full. I checked the connection under the cab (where it enters the harness with other wires) and that connection is good.

So...bad sending unit? It worked until recently, but it could have failed. Just don't want to spend money on another if there's something else I should check. That it reads Full with the wire disconnected makes me think it's electrical, but I don't understand how the thing works.

That symptom indicates a bad (or, no) ground, usually from the sender to the body/frame. Try running a small ground wire from a sender-to-tank attachment post/bolt to a good ground (on the frame, or run a small ground lead back to battery ground).

I'm unclear. Should that ground wire run from that center post where the pick-up wire (sender unit to gauge) attaches? Or from one of the 6 small bolts that attach the sending unit to the tank? The former doesn't make sense...grounding the signal wire.

No - not the "pickup/sender/signal" wire - that wire is the "hot" lead to/from the gauge.

I think you have it figured out correctly:
Ground one of the 6 small bolts that attach the sending unit to the tank.

Done and done! thanks.