Notice

NOTICE: We will not be processing any repairs until after Feb 26th allowing time for the weather to clear up so that things can get back on schedule. 

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.