I’ve been cleaning up some minor issues on my 80 cutlass supreme . And one thing on my punch list is the fuel guage it never reads more than quarter tank . It does drop below empty as I use the fuel .Is it almost always a sending unit that causes this problem? What are some trouble shooting techniques I can follow before dropping the tank ? Thank you

 

Disconnect the wire at the sending unit. If the gauge moves well past full you know the gauge needle is physically capable of reading above full. If you ground the wire, the gauge should read empty. If all that checks out, time to drop the fuel tank. Either the sending unit float is binding on something (preventing it from moving above a 1/4 tank) or the sending unit is electrically defective.

 

Thank you Matt I’m going to check it out tonight honestly I’d rather it be the sending unit than the guage