Fuel gauge

[MiLo]

When I bought my car the fuel gauge was stuck just under the full mark. How would I fix this problem? Im about tired of resetting the odometer every single time I refuel.. Can this be a sensor that went bad? Or is the gauge just broken?

[AleroB888]

When I bought my car the fuel gauge was stuck just under the full mark. How would I fix this problem? Im about tired of resetting the odometer every single time I refuel.. Can this be a sensor that went bad? Or is the gauge just broken?

This can be an indication of a more serious problem with the fuel pump, sometimes corrosion on the sending unit causes the resistance to vary, so the gauge reads incorrectly. iirc, Techron additive can sometimes clear that up. But even if it does, there may already be corrosion in the pump itself. Hopefully, not.

[MiLo]

Is there way to check if there is any corrosion without having to take off the fuel pump? As I said its stuck at the full position. Its not like the gauge jumps around

[Shiwnath]

If you unplug your gauge cluster and plug it back in, the needles will do a full sweep. You can try this to see determine if the motor still functions to rule that out as a possibility.

[a.graham52]

i agree, try what Shiwnath said, if the gauge sweeps, then you KNOW its not the GAUGE. unfortunately the step after that is going to C411 ahead of the fuel tank. unplugging that connector should make the gauge default empty. shorting the signal wire to ground will make the gauge go full. if it works there then you have a problem in the tank. 9 times out of 10 its the fuel level sensor in the tank its self.

[MiLo]

i agree, try what Shiwnath said, if the gauge sweeps, then you KNOW its not the GAUGE. unfortunately the step after that is going to C411 ahead of the fuel tank. unplugging that connector should make the gauge default empty. shorting the signal wire to ground will make the gauge go full. if it works there then you have a problem in the tank. 9 times out of 10 its the fuel level sensor in the tank its self.

Im still learning so can you explain the c411 scenario please.

[RalphP]

Im still learning so can you explain the c411 scenario please.

Unplug connector # 411 (C411), the one at the fuel pump / sending unit.

Fuel gauge should go to EMPTY.

Ground the wire that the fuel sending unit is normally connected to.

Fuel gauge should go FULL.

Before doing this, obtain a competent service manual and/or sign up for All Data DIY for a year, so you can get drawings and explainations of which wire is which on the connectors.

RwP

[a.graham52]

c411 is NOT at the sending unit, its on the body in front of the fuel tank. which is good because you can check the 90% of the fuel gauge circuits at this point without dropping the tank.

[Cliff8928]

I think you're actually referring to C413...

[a.graham52]

I think you're actually referring to C413...

i ment c411 BUT GM's "master electrical list" could be worded wrong, said 411 was in front of tank on body

[RalphP]

c411 is NOT at the sending unit, its on the body in front of the fuel tank. which is good because you can check the 90% of the fuel gauge circuits at this point without dropping the tank.

So the one AT the tank, NOT the one ON the tank.

I see no need to correct what I typed :p

(BTW - I didn't say "at the sending unit", I said "at the tank". I know, doesn't sound like much difference, but I do tend to be fairly precise in what I say. Chalk it up to my touch of Sheldon-ism.)

RwP

[a.graham52]

So the one AT the tank, NOT the one ON the tank.

I see no need to correct what I typed :p

(BTW - I didn't say "at the sending unit", I said "at the tank". I know, doesn't sound like much difference, but I do tend to be fairly precise in what I say. Chalk it up to my touch of Sheldon-ism.)

RwP

i see no evidence of "at the tank" anywhere haha.