86 camaro gas gauge is not working...fuel injected, 6 cycliner, standard. Otherwise runs well.
Arros falls below the full area...once in a while it moves towards full, but drops down again below the full side. THe gauge does not move to full when the tank is filled.

it's either a wiring problem (broken insulation, wire shorting to ground.)between the guage and the sender, or a bad sender. To check it, locate and disconnect the wire at/near the sending unit. In a 1st gen, this connector is at the rear center of the trunk, not sure about yours. With it disconnected, the guage should go to past full and stay there. If it doesn't, the wire or guage is bad, grounding out forward of where you disconnected it. Next, ground the wire to the body with a jumper. The guage should go to empty and stay there. If both tests pass, the sender is bad.