Assuming the gauge is connected correctly, disconnected the wire that goes to the sender. Momentarily ground that wire to the frame (with the key on). The gauge should peg full. If it doesn't peg full than the problem is not the sender.
If the gauge has power to it and the wires aren't reversed than the gauge is the problem.
Last edited by Bogart's Truck; 05/25/2017 9:37 PM.
