Fuel Sender

Toby,

explain "not working". Is the gage reading empty, full, or somewhere in between?

The sender is a variable resistance, a rheostat if you will. The resistance at empty is 200 ohms, the resistance at full is zero ohms (a short circuit). The circuit is powered by fuse #12, which also powers the oil pressure & coolant temp circuits.

If all 3 gages are non functional, check the fuse.

If the gage is reading empty, this would indicate an open circuit, a wire is not connected. If the gage is reading full, this would indicate a short circuit, possible to the chassis, or between the two wires.

good luck, George

Sorry George, gauge is reading empty. Should i attach a volt meter to one of the wires?

Toby,

disconnect both wires & measure the resistance between them, the resistance should be somewhat less than 200 ohms, depending upon how much fuel is in the tank.

If the resistance is less than 200 ohms, and is approximately correct for the amount of fuel in the tank, then you have an open circuit elsewhere, perhaps a bad ground or a loose wire behind the fuel gage. If the resistance is right around 200 ohms, the sender is stuck at the bottom (or no longer buoyant). If the resistance is very high, in the thousand ohm or meg-ohm range, or even infinite, you have a poor connection or an open circuit in the sender.

George

George, thanks for the help. I measured resistance at 80 ohms. Then I quickly swapped the two wires on the sender and the gage jumped to life at just over 1/4 tank. I must have initially replaced the wires backwards.

Toby