The fuel gauge wire doesn't travel down the middle of the body. Even if it did, the vehicle is full of wires that commonly get wet. Water can cause corrosion in unsealed connectors, but it won't cause a problem with wires unless the insulation has been cut.
Hopefully you have overlooked an important clue. It is very common for the gauge to read properly when the tank is between half and full, and between empty and a quarter full. Typically, between 1/4 and 1/2 tank, the gauge drops to below empty.
The points at which the gauge cuts out can vary, but will usually be fairly consistent on a given vehicle. The fix involves making a minor modification to the sending unit's float arm. No new parts are required.
To verify the sending unit is the problem, find the four-wire connector near the fuel tank. Ground the dark blue wire while the ignition switch is in the "run" position. If that makes the fuel gauge read full, that proves the wiring is ok up to the tank.
Sunday, February 21st, 2010 AT 8:09 AM