Erratic fuel gauge reading

[longrowe]

I have a 1998, ROW C2. Over the past two weeks I have noticed that the fuel gauge is not reading correctly. The gauge will read high (3/4) but as I drive, the gauge will slowly drop to the correct reading over about 15 minutes. As the car sits, either at work for the day or in the garage overnight, when I go to start the car, the gauge will read over 1/4 tank higher than when I shut it off. Then, as I drive, it will drop to where I think it should be (or remember where it should be). I plan to pull the sender this weekend and check the connections, but I don't think it is the float as why would it rise while the car is turned off? Is it possible to troubleshoot the cluster gauge? I have a Durametric so I will attempt the fuel level calibration when I have pumped down the tank. Or am I just fooling myself and the gauge is bad?

[Loren]

I would think it more likely the sender inside the tank is bad or gummed up with residue.

[judgejon]

Yes, fuel sender issue is likely problem.

On older Porsche cars you could simply pull the sender unit out of the top of the fuel tank.

I'm not sure, but check to see if there is a sender unit on top of the tank that could easily be pulled out and replaced.

Could be a sender similar to the oil pressure sender.  Relatively inexpensive to replace.  Labor would be the biggest cost.

Good luck.

[longrowe]

Thanks for the confirmation that it could be the sender. Mine is inside the tank. I will open it this weekend and clean it up. We'll see if that clears it up.

[Schnell Gelb]

While you are in there - check for deteriorated fittings and valves. Some of these cause the EVAP codes .

Edited May 23, 2017 by Schnell Gelb

[longrowe]

Pulled the sensor out and cleaned up the contacts, actuated the arm. Everything seemed to move freely. That must have done the trick as it is reading correctly again. Filled up and no problems with the gauge moving. We will see. Thanks for all of the input!

[judgejon]

Great result.  Cheers.