Gas Gauge Problem

Q: Gas Gauge Problem

ok guys I have one I can’t figure out my gas gauge reads empty when I still have about 8 gallons left in the tank but my main gripe is when I turn on my lights the gas gauge swings over to empty even with a full tank but when I turn the lights off it will swing back to where it is suppose to be at can anyone help me on this thanks

A: Check the ground wire and connection. One end is connected at the sender(on tank) which you will have to drop tank to see it. The other is near the filler neck attached to the trunk floor pan with a large sheetmetal screw. Bad ground will give the sender all kinda different readings. You can test it to see if the sender or wire or gauge is the problem. Use a VOM to check for voltage and disconnect the sender(positive) wire and ground it. You should see it move the gauge full scale. When that circuit is open it will swing the gauge the other way. Set the VOM on to Ohm scale to read the sender. GM used 0-99 Ohm for the sender values. Half way should mean 1/2 tank.

A: The sending unit is comprised of rheostat and wiper arm. The rheostat is a resistive wire wound along a shaft in a progressive spacing. The wiper arm, which is attached to the float, moves along the windings and changes the resistance value of the rheostat. What tends to happen over the years is the windings become worn, then thin and begin to move on the shaft. This effect turns into dead spots along the rheostat where the wiper should make contact. These dead spots will result in a no reading on the fuel gauge or a non uniform reading. Eventually, the windings break and no fuel gauge operation is the result.

Recommendation. You’re going to have to pull the sending unit anyway to inspect it. Replace it with a new unit. Not worth trying to fix the old one.

A: Sounds like a bad dash ground. Save some time and just rig a jumper from a good ground then, reach under the dash and touch the metal housing of your gauge cluster. If the ground was bad, you’ll notice your problems will go away. Once you’ve confirmed that the ground IS t

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