Fuel gauge not working ... Even after replacing sender - 2008 Tahoe

Huntster · March 23, 2014

Hoping someone can give me some guidance please:

A few months ago the fuel gauge stopped working (shows bone empty, however no warning light, sometimes light will go on for a minute and/or the gauge will start to partially work).

Now P0449, P0453 and the oxygen sensor codes are being tripped which I assume is due to the fuel level malfunction.

Today I replaced it (whole pump assembly) and checked the old unit. Old unit was reading 270 ohms on a near empty tank (these trucks have plastic fuel tanks by the way!) so I assumed that was indeed the problem with the fuel gauge. New one was 40 ohms and 240 ohms.

Started it up and the gauge reads the same ... Empty with no light on (light comes on during pre-ignition). I'm getting code P0463 "Fuel level sensor A Circuit High". I ran a live vehicle scan and the fuel level is reading as "0%".

Had anyone seen this problem or have any ideas how I can proceed? I am overdue on inspection and need to get this fixed soon.

Thanks in advance!

DwelveAT · March 24, 2014

I could be wrong, but something to possibly check out. Could it be a bad instrument cluster?

Huntster · March 25, 2014

I got the factory service manual which indicates P0463 usually is not indicative of a bad sender but of a connection or wire problem either at the ECM, etc. Well, I threw in the towel and took it to the dealer to have them find the wiring bundle running above the front driveshaft had been rubbing and was fraying so badly that the fuel sender wire was in half. Ouch. Thumbs down to GM for designing the wiring support like this. Anyone getting a P0463 (not due to frozen temperatures) should do a thorough inspection of the wires going up the vehicle.

Huntster · March 25, 2014

Picture evidence:

gmtech4 · March 25, 2014

i guess ya never get under your truck to much or have a guy look at it ,,,holy crap bud ,thats not good

to everyone that reads this ,,,,this is the real reason to have it diagnosed and not to throw parts at your truck !!!!!!!!!!!!!!!!!!!!!!!!!

other reasons for a code than the part is my point !!!!

Huntster · March 26, 2014

govtech4, the fuel pump cost $177 .... having it diagnosed would have been $100. The sender was $70, and frankly my time is valuable enough that if I'm going to remove a fuel tank, I'M DEFINITELY REPLACING THE PUMP. Maybe you have lots of time to play with your truck but I do not. And yes I was under my truck for HOURS, even looked at the driveshaft and cable and NEVER SAW THE FRAYING WIRES. Perhaps the angle of the picture is deceptive or a lift totally changes the perspective, but I could not see these just being under the truck.

I do agree that a more thorough inspection would have been prudent, but there is ABSOLUTELY NO GOOD REASON THIS WIRE CABLE WAS HITTING THE DRIVESHAFT. In fact, the factory service manual only recommends examining the connections at the tank (dropping the tank) and at the ECM.