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2005 Lincoln Towncar fuel gauge

Trouble with the fuel gauge showing full all the time - only goes down 1/8th at most. Repair shop said it would cost $2300 in Las Vegas, NV. They said would have to pull dash to find the trouble. Any ideas? Thanks.

Pull the dash? You only need to remove the instrument cluster. The problem is generally going to be in the cluster, at the fuel level sensor in the trunk, or a short in the circuit, usually near the tank, where it is most exposed.

First, I would make sure the tank was half full or less, pull the cluster, and check the ohms reading of the sender signal wire. Add 5 or more gallons of gas, and recheck. The value should change significantly. If it doesn’t, the problem is near the tank. If it does, the problem is in the cluster.

The float on the fuel pump may be hanging up. With the tank half full, go under the vehicle and bang on the gas tank with a rubber mallet to see if the fuel gauge drops.

Tester

…and until you get the problem fixed, you can use the trip odometer a a stand-in for the fuel gauge.

Fill the tank, zero the trip odometer. Fuel capacity X MPG = miles to empty; try not to exceed 75% of that value.

Your fuel tank is mounted vertically behind the back seat…There MAY be access to the fuel sender and fuel pump electrical connectors through the trunk or by removing the rear seat back…It’s the same as a Crown Vic or a Grand Marq…See a Ford specialist who knows these cars…