Notice

NOTICE: Due to Heavy Work Loads we are currently running around 8-10 days on our turn-around after we receive your unit in for repairs.

Faulty sender units are common to some GM vehicles, but generally speaking will start malfunction at the same fuel level every time due to wear at the sender grid.
Also, you may get a fault trouble code which is usually an indication of a faulty sender or circuit.
A malfunctioning gauge esp. on some GM vehicles will be stuck and not move at all or be off the scale altogether.