Just noticed this a couple of times now, the gauge works, and it's not acting like the need was off and replaced incorrectly, the gauge just jumps around more so when the tank is getting low. I had a quarter of a tank left earlier, ran maybe 10 miles round trip and the needle was buried on E. Then it comes back up a little, but just goes back and forth between E and 3/4.

Or if the car is off, the needle will hoover around half, then as soon as I pull the key, go straight to E. Any idea's? Could it be the Fuel Level Sensor? Like commonly wrong in the Trailblazer's?