Typical fuel gauge wiring and operation.
Power ( + ) is hooked to one side of the fuel gauge. It should be a fused circuit.
Power flows through the gauge and comes out the other side terminal post,
Power ( + ) leaves the gauge is on its way to the sender by way of wire harness,
At the fuel tank is the sending unit, center post is ( + ) wire hook up, mounting pad with five screws is the ground ( - ) side of the circuit.
( + ) flows through the sender to reach ground ( - ). If the tank or sender is not grounded properly, the gauge will not function.
The fuel level varies the resistance to ground, so the gauge needle varies from full to empty depending on the resistance in the circuit at the sender.
YOU MUST HAVE A CLEAN GROUND CONTACT at the sender and truck body or frame.
Run a test wire from gauge to sender and sender to ground post on battery, if the the gauge is good and sender is new, it should work. Its easier to remove the sender from the tank for testing.
Joe
