Tank is full but guage says emty

Sounds as if the SENDING UNIT in the tank is faulty. They work by RESISTANCE, so when the contacts on the fuel guage sending unit in the tank get worn, it will send incorrect data. Typically it will say full when the actually IS full, then, when the tank is 3/4 full, it will say EMPTY, and then, as you use more fuel from the tank, the guage will go from what is REALLY in the tank, to empty, at different times.

Only solution is to remove the fuel tank, and replace the sending unit guage assembly.

You can take out the part of the dash where the guages are and change the little sensor/fuse behind the fuel guage, they should have a replacement part at orileys or autozone

fuel guage in tank needs replaced or a faulty earht wire.adrian,,,,,,,,,,

with the needles off and the scanner set to calibrate the speedometer and all the rest of the needles need to be installed at 1/2 full range with the system on unless otherwise noticed by the scanner.

i whould say replace sending unit in the tank.

it sounds like the level sensor on the sender (fuel pick up pipe in the fuel tank) is getting stuck. the level sensor is a float that is attached to the sender, and you will need to remove the fuel tank to get to it.

hope this helps.

The gas guage has a sending unit in the tank attached to the pump, there is a small circuit board on it that has smal"fingers" that send the signal to the guage.These get worn off and thus sends a false reading to the gas guage in the dash. The gas tank must be removed and a new unit put in to solve the problem. I had to do this repair to mine. As for the gas issue, just try pulling the nozzle back out of the filler neck when putting gas in, sometimes the overflow tube gets plugged up and won't allow the air to escape as the gas goes in the tank, making the gas pump think the car is full, pulling the nozzle will allow the air to escape. Hope this helps.

khooper, in another forum, told me that "Chevron Techron Fuel System Treatment Plus can remove harmful sulfur deposits from the sending unit and a filmer agent that can prevent the deposition of said sulfur"

My 05 Trailblazer LT 2WD.
Erratic readings, and when the fuel level was below 1/2 full, the needle would sit on "Empty" with the amber light staying on.

So I went to a dealer, they replaced the fuel level sensor (p/n 19177712 SEN KIT 3.107 $118.62) with labor $270.00 for a total of $398.86 this appears to have fixed it for now.

I also talked to another mechanic who blames ethanol for these deposits !

Your needle moving from empty to full and then back to empty indicates that it is trying to set itself (most cars do this each time they are started). So, yes, there seems to be a problem with the sending unit that feeds information to your gas guage. Prior to cracking open your fuel tank, you might try tracking the wires from the back of your guage as far as you can towards the tank. Then track the wires from your tank as far as you can toward the guage. Watch for damaged wires and/or loose connections as you go.

Ajkill is right. I had the same problem with the fuel light always being on and the guage read empty no matter how much fuel is in the tank. I had to have the fuel level sensor in the tank replaced. This is something that they have to drop the tank for. It was about $400 with the part and labor at the dealership.