WHAT IS CAUSE OF ERRATIC FUEL GUAGE? on 1999 Chevrolet Silverado 1500

GUAGE GOES TO EMPTY EVERY TIME TANK IS FILLED. MAY SHORTLY GO TO FULL OR STOP ANYWHERE IN BETWEEN. IS ACCURATE MOST OF TIME, BUT CAN FLOP AROUND UNDER ANY CIRCUMSTANCE.

3 answers
connector on fuel pump sending side,will eventually lead to fuel pump failure.GM is aware but does't care.New after market pump will have updated connector and works perfect.
YOUR SENDING UNIT IS MALFUNCTIONING. IN THE TANK YOU HAVE A FUEL PUMP AND A SENDING UNIT I REC YOU CHANGE BOTH AT THE SAME TIME
FUEL PUMP OR FUEL REGULER