[VetteVet]

This is an indication that the sending unit wire to the gauge is grounded to the frame and not grounding through the resistor in the sending unit. Pull the sending unit wire off the unit at the tank and with the key on you should get a gauge reading at 3:00 o'clock.

If it still reads where it's at, then pull the sending unit wire off at the fuse panel and re-check the fuel gauge. if it then goes to the 3;00 o'clock then the sending unit wire is grounded between the fuse panel and the sending unit. Possibly pinched and grounded somewhere.