Re: Fuel gage error

My 2003s has been reading about a quarter of a tank low when filled. It might be sticking since once I drove over a rough patch and it bounced correct. I tight I might have had a bubble in the tank a few times. Anyone with this experience? Thanks

Quote
juliof16c
My 2003s has been reading about a quarter of a tank low when filled. It might be sticking since once I drove over a rough patch and it bounced correct. I tight I might have had a bubble in the tank a few times. Anyone with this experience? Thanks

The only time my Boxster's gas gage reads low when I fill the gas tank -- or think I fill it -- is when the gas pump nozzle shuts off prematurely. This doesn't happen very often but when it does happen or I think it has happened I sometimes walk around to the driver side and turn on the key and check the fuel level and then add more fuel if the level is not up at the full hash mark. But sometimes the shut off "feels" right and the amount I've added also "feels" right and I assume the tank is full and don't bother to double check. Only when I get in the car and am ready to leave do I notice the tank level is down a bit from "full". I'd estimate a couple of gallons based on the times I've caught this and added more fuel. Just a couple more gallons brings the level up to the full mark.

I have never observed the level changing -- rising -- after filling the tank.

In the case of your car I don't believe a "bubble" in the tank is an explanation.

Furthermore, the tank fuel level mechanism is probably not sticking as the fuel will keep the mechanism "clean" and free to move.

What can happen is a fuel line (or something) in the tank comes loose and can interfere with the mechanism. The rough patch of road you encountered jarred the fuel level hardware and freed the mechanism to move freely. Temporarily.

The above ignores a possible sensor malfunction but the symptoms do not read like a sensor malfunction. I believe were a sensor bad the symptom would have the level reading either empty all the time or full all the time.

It might be worth the effort to have some Porsche diagnostics computer time to eliminate a sensor problem because the other step would be to I believe open up the tank and remove the fuel pump and check the fuel level mechanism for interference with something in the tank or possibly some mechanical failure of the fuel level hardware.

... a PST-II or PIWIS computer and have them calibrate the gas tank gauge.
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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Yep, same thing happened to me (987 Base)... and my indy resolved it with the procedure that Pedro describes. The labor was higher than expected because the recal required the tank to have a specific amount of fuel in it for the reset.

the level appeared to correct itself after driving on a rough section of road. This points to a mechanical problem something is interfering with the fuel level hardware's operation.

The OP is certainly free to try the re-cal thing. Unfortunately it is a bit expensive due to the labor to remove the existing gasoline and add back in a very specific -- and accurate -- amount.