Fuel Guage not working

[99SUB4X4]

1999 Suburban. I have had it for 8 years and the fuel gauge has always randomly swung back and forth from E to F, F to E. It will stop in either position for awhile and then swing to the other. It will do this with a fresh fill up with no change as fuel level drops. Any ideas? Poor connection at the sender? I always fill up at 400 miles and haven't ran out of gas so far. Would be nice to have a working guage. Thanks!

 

[AK49BWL]

There's a problem somewhere between the PCM and the sender, could be a ground, pinched wire, etc - or could be the sender itself has dead spots, depending on if it's ever been replaced, age takes them out...

Note: your gauge itself is probably fine, sounds like it's acting as designed - the PCM has control of it. It does seem strange to me it only shows full and empty, nothing in between at all? Normally when the PCM detects a failure condition it will command the gauge to empty and stay there. If signal from the sender comes back, the PCM commands the gauge to the proper position according to the resistance of the sender.

 

[grampadirt]

Wifey's 99 burb had the same problem,I took a wild guess and removed the fuel tank to have a look at the fuel level sender.Well guess what? some of the little ''fingers'' that ride on a little coil had broken off.So checking on Rock Auto's web site I discovered just the level sender can be replaced,problem is it's about the same price as the entire fuel module,so I replaced the whole thing and now works as it should.

 

[Pinger]

My fuel gauge must be happy - judging by how enthusiastically it waves at me....
Recently, I repaired the connection at the fuel module pigtail and that improved things for a while but it's as erratic as can be again. Doubting that my (properly soldered and sealed) repair has failed I'm beginning to think the problem is in the tank - which is around half full and as we all know a PITA to drop. Not a massive priority for me as I only have to add gasoline every year or two (runs on propane - gasoline is only for cold starts) but it'd be neat if it worked as it should.

OP: Check the aforementioned pigtail. On my Suburban it was easiest accessed from the front side of the tank.

 

[99SUB4X4]

Thanks for the replies all. I will probably look deeper into this when I change the fuel pump. I will give that pigtal a looking at as that is the easiest to start.

 

[OBSOkie]

Here’s the troubleshooting from the wiring manual.

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[Cherryred98]

What book or manual is that trouble shooting sheet from? Just out of curiosity. I have a similar problem, my gauge is erratic. It will be empty and read empty, I’ll put 4 gallons in and it read full, gauge most of the time will read either empty or full, but when I turn the ignition off I get a reading that seems closer to what I think is in the tank. (1/8, 1/4 ect) my gauge isn’t smooth when it moves it jumps around sometimes past full to almost the 2 or 3 o clock position.

 

[AK49BWL]

If it's going that far past full, you have an intermittent wire break somewhere, possibly two. The gauge has no power with the ignition off so it's coincidental that it might line up when you turn the key off. The gauge usually will not go to the 2-3 o'clock position unless there's a straight up open circuit between the gauge and PCM (or tank for earlier models than 98).

 

[skylark]

Use a scanner to check the live data. This will tell you if everything is good from the tank to the pcm. This will help you narrowed down the issue.

 

[skylark]

This was a common problem as well.

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