Faulty fuel gauge

[spina74]

Ok, so my fuel gauge reads but it doesn't read correctly. I know putting 5 gallons in from empty doesn't equal three quarters of a tank, also when the needle hits a quarter it drops to E, trips the check gauges light then eventually pickups back up. I'm guessing I have a bad fuel sensor, or do I have to change my cluster.

[BonzoHansen]

it runs through the ecm too.

[Stevoone]

The gauge works from resistance readings on the level sensor. 40 Ohms = empty 165 Ohms should be about half and 250 Ohms should be full. Sounds like the Level Sensor but if you wanted to check to make sure any GM shop should have the tool 33431-C is the tool number.

There should also be an after-market tool available. I have also used level sensors from other cars to check the gauge operation. Jumper a different level sensor into your fuel tank harness and manually move the float arm, your gauge should move accordingly. I think I have a few in my tool box if u need one to test with.

[Formulalt1]

Because of the shape of the tank this is a problem that has been disscussed for years, almost all 4th gen owners I talk to say that there car stays at full to 3/4's for a while but once they hit 1/2 tank they go right threw it. I think its a combination of the sending unit mounting and the shape of the fuel tank.