Fuel Gauge: Description and Operation

The fuel gage indicates the quantity of fuel in the tank when the ignition switch is in the "RUN" position.

The fuel gage measures current from a variable resistor inside the fuel tank that is controlled by a float.

When the fuel tank is full and the ignition switch is in the "RUN" position, resistance is high and the fuel gage indicator moves to the maximum position, or "FULL", on the gage face. When the fuel tank is empty, resistance is low and the fuel gage indicator moves to the minimum position, or "EMPTY", on the gage face. Corroded connections or severed ground paths generally cause the indicator to register past "FULL" on the gage face. Short circuits to ground generally result in the indicator resting below "EMPTY."

The fuel gage sender assembly mounts to the top of the fuel tank, and is retained by a cam-type locking ring. A seal is used between the fuel tank and the sender. The fuel gage sender assembly consists of a float attached to a variable resistance sender, a woven plastic filter on the fuel pickup tube, and a vane-type electric fuel pump.

The fuel gage sender will have two or three hose connections. One is used for the fuel feed hose, the second connects to the vapor canister, and the third is used for the fuel return line to the fuel tank. On some fuel tank senders, a short connector lead is used. Others have the connector attach directly to the sender.