Inaccurate Fuel Gauge

[vdiblasi]

1999 C2 911.

After refueling gauge reads a 1/4 tank low. When low fuel lite comes on, I refuel and it only takes around 10 gallons. Can fuel gauge be calibrated electronically or must it be removed from the car?

Thanks for any help.

Victor

[Loren]

Your problem depends on whether it is the instrument cluster gauge or the sending unit in your fuel tank.

Have you (or a previous owner) replaced the instrument cluster dials? Does the needle stick?

If it is not obvious then you will likely need a PST2 or PIWIS tester to further troubleshoot.

[logray]

For what it's worth my 99 C2 996 does the same thing. IIRC there are a few posts describing this. As well as in the owners manual describing what levels the low level light will come on. IIRC there is a gallon or more in the reserve, and when the light goes off it's actually well before the tank is completely drained, my OBC usually says I have 70-90 miles left. The most I've put in the car is about 14.7 gallons. If I fill up right when the low fuel light goes on I can probably only get 10 or 11 gallons in. To get the meter to read full, I have to sit there and top it off for a long time and it's not worth it for the extra gallon or two. Lately with gas prices I've been putting in $40 regardless. I have a PST2 FWIW, but haven't bothered to troubleshoot. I think in a C4 there is a TSB that there is a similar expected behavior, due to the way they had to fit the fuel tank in to compensate for lack of room with the drivetrain.

[gusmagoo]

Yours is a C2, so you won’t have the known issues caused by a split tank that the C4 has, however there are a few anomalies with the readings for fuel which are well discussed if you do a search.

If you have a handbook and follow the rule of thumb they advise you shouldn’t have any problems, if you do, your sender might be at fault.

Fill up as soon as possible after the warning light comes on, and don’t try and squeeze every last ounce into the tank once the fill nozzle knocks itself off. The fuel gauge indicator gives an estimate of mileage left not an accurate figure and if you only put a very small amount of fuel in, the gauge might not move at all, this is normal, as it only registers when filled above a certain level.
Despite me saying all this, it does sound like your sender may be at fault. A good indie will be able to replace this.
Let us know if you sort it out.

[vdiblasi]

Yours is a C2, so you won’t have the known issues caused by a split tank that the C4 has, however there are a few anomalies with the readings for fuel which are well discussed if you do a search.

If you have a handbook and follow the rule of thumb they advise you shouldn’t have any problems, if you do, your sender might be at fault.

Fill up as soon as possible after the warning light comes on, and don’t try and squeeze every last ounce into the tank once the fill nozzle knocks itself off. The fuel gauge indicator gives an estimate of mileage left not an accurate figure and if you only put a very small amount of fuel in, the gauge might not move at all, this is normal, as it only registers when filled above a certain level.
Despite me saying all this, it does sound like your sender may be at fault. A good indie will be able to replace this.
Let us know if you sort it out.

Thanks, will do.