Fuel Gauge Erratic

For years the fuel gauge has worked great. One time I had the replace a plastic float the filled with fuel. Then all of a sudden it always on empty. I was assuming float again, but then several times lately, I look down and it’s ready some level. Next drive it’s empty again. I’m now thinking maybe a bad ground. Thoughts of where to start looking.

 

Bad wire or connector someplace. Or ground, perhaps at the tank(?) Unless the rheostat in the tank is acting up.

There is a voltage regulator in the instrument cluster - is the other gauge working normally? Do NOT operate the cluster when it is not grounded, so they say.

Other members have published good info here before.

 

Did you read the FSM? There should be step-by-step in the FSM. Suggest you check the FSM before you post.

To start, I would divide the system in half: the gauge, and all the rest. I'd do all the rest first.

The sender in the tank is a variable resistor, like a rheostat. That's all it does - changes the rheostat setting depending on the fuel level. Aside from the gauge in the dash, all the rest of this half is just wiring.

You can get to the sender easily, under the driver's seat. Do you own a multimeter and know how to use it? Disconnect the wire. I would first measure the resistance from the sender terminal to the flange of the sender. There is a spec in the FSM. Then test the resistance from the terminal to the body.

If that checks out, I would move to the other half, the gauge. You can replace the sender with a fixed resistor or rheostat/potentiometer set to the correct value, from the disconnected wire to the flange or body. The gauge should move to the level given by the resistor value.

If all this checks out, and the gauge is still intermittent/wonky, I would next remove the sender and test it on the bench.

 

X 2 What Timgr Said.