Screwy Gas Gauge

['68OrangeSunshine]

The Fuel level indiccator on my '03 Chevy C/1500 Tahoe has been acting weird lately. Sometimes, it will stay on Empty and the yellow light stays on, even after topping off the tank.
The other night it was sometimes showing about 9/16ths full, then dropping to half full, then almost zero.
I filled it up. Tank took 13.8 gallons. Legitimately a half tank, but the gauge stayed on empty and the yellow idiot light stayed on.
Once up in the Foothills, after midnight -- and no cops around -- I made some quick, G-inducing lane changes -- to slosh the tank internally. It worked for about a minute, then the needle sank again. It's been doing this for a couple months.
Then sometimes, the needle pops back up and reveals the true level.
IDK.
I have been logging trip miles, fill-ups and gallons taken onboard. My MPG has gone down.

Where do I start troubleshootig?

[RustyPile]

Sounds like either the float is hanging up or sticking.. Also possible the sending unit is failing.

['68OrangeSunshine]

Sometimes a hard turn will get the gas sloshing to the sides, and that wakes up the float.
But then as often as not, the level drops to E again. Then sometimes the level comes back to its true 3/4 full.
Baffling.

[Accelo]

This is a known issue with the fuel level sensor. It is part of the fuel pump. I suggest replacing it. Not a bad job. Remove the tailgate, unplug the wiring and remove the screws from the fuel fill. Loosen all the bolts, box hold-down bolts, on the passenger side and remove them from the filler side. Lift one side of the box and insert a 2x4 to hold up. Takes two people for this part. Then you have access to the top of the tank. I have completed this on several trucks, and all of them had the same issue. This approach is often preferred over dropping the entire fuel tank, as it can save time and effort.
Cheers.

['68OrangeSunshine]

Originally Posted by Accelo

This is a known issue with the fuel level sensor. It is part of the fuel pump. I suggest replacing it. Not a bad job. Remove the tailgate, unplug the wiring and remove the screws from the fuel fill. Loosen all the bolts, box hold-down bolts, on the passenger side and remove them from the filler side. Lift one side of the box and insert a 2x4 to hold up. Takes two people for this part. Then you have access to the top of the tank. I have completed this on several trucks, and all of them had the same issue. This approach is often preferred over dropping the entire fuel tank, as it can save time and effort.
Cheers.

Thanks for the instruction. My Tahoe has Barn Doors, no tailgate, so I guess I just skip that step?
I've had this truck for about a year and a half.
The Fuel Indicator gripe didn't start until I very nearly ran it out of gas on a run to San Diego from Tucson in July. It went 'Bingo' about 14 miles from the AZ border on the return run. Gas was $10/Gallon in Cal. [And $3/Gal in AZ] Before it stalled, I pulled into a rest stop and called AAA. The rescue driver sold me a gallon for $!0 and I made it 2 miles to a Chevron station where Regular was $7/Gallon. I bought two more gallons and cruised to Yuma, where I filled up at $3/Gal. Took on about 23 gallons. I'm guessing tank's max fill is 25 gallons.