My car has been in storage for a few years now...only cranked up here and there. The other day when I pulled it out of storage the gas gauge bounced up to full and then back down to 1/4 tank. After a few minutes of idling it went all the way as far to the right as it could go and stayed there. The car runs fine otherwise. The tank is not full. Is my fuel pump about to give up the ghost?

 

I had this same question a while back. People have told me that GM factory gauges are a little weird. For ex., when it says a 1/2 tank, its really a quarter and so on.

 

While the calibration of the stock gauge is "off", that wouldn't explain the gauge moving suddenly from 1/4 to full and back. Sounds like a bad connection on the wire from the level sender to the gauge, or the sender itself. A full right indication generally reuslts from an open circuit.

 

Yes this is most likely an issue with the sending unit in the tank.

I had a similar issue when I took a long road trip and it turned out to just be nasty gas causing it. After a 2 fill ups locally at QT and the gauge started working right and has not had any other issues.

If you are not as lucky as me you will be needing a new sending unit which means dropping the gas tank.

Good Luck!