Minok

So the fuel sensor failed. It can happen. Did you have the mileage system showing how many miles you had gone since a refill (trip odometer)? If it was at the limits of the range I normally get, that would be a clue that the fuel gauge is lying to me.

So what does it cost for a new fuel gauge sender unit? (or is it some other part in that indicator system)?

Sniff

Absolutely. In fact I have been tinkering with a new invention in my garage . . . electronic pressure sensors mounted inside the wheels that will send signals to the console readout indicating tire pressure. I am thinking of calling it TPMS. I will make millions.

Sean

Philster

To the best of my knowledge, my "miles to empty" was around 65 and needle was just under 1/4 line. Low fuel light not on.

She is full now. Needle is pinned as high as it'll go up high on the gauge. Not in front of it, but miles to empty is now 300 miles plus.

sjfehr

How many gallons of gas did you add to bring it to full? How much do you normally add? If it's a 14 gal tank and you're adding 13.5 gallons when the gauge shows 1/4, that'd be a sign, too. Anecdotally, the tanks seem to hold a little more than rated for, and the low fuel light is supposed to come on with 2 gallons left, but...

I had a camaro once I mistakenly let run too low; realized it was pegged low about 3 miles from a gas station. On the way, it lost power accelerating from a stopsign, recovered, and then started sputtering as I pulled to a stop at the pump. I then proceeded to put 15.5gal into a 14.5 gallon tank, lol.

GermanCarSpecialists

Funny story. We replaced a battery on a 7.1 last month and a few days later customer called me yelling his car would not start. I offered him a tow service back to the shop. He chose to take it to the dealership. It sat at the dealer for 3 days before someone could get to it. Then it was diagnosed with no gas... :SMH:

Now, I do not know the circumstances or the similarities of my customers' situation to this one.

P911CS

BRILLIANT!!! with a GUINNESS!!!

Fred R. C4S

A few months into the ownership of my new 2003 996TT, the fuel pump in the gas tank quit. The fuel level sending unit is part of the pump. In simple terms it's a variable rheostat with a float moving a device that changes resistance seen by the gauge. From this, fuel level is measured and displayed. A simple system in use for decades on anything with an electric fuel gauge.

Now to the "Porsche" twist on things. When replacing the pump unit, the sender and gauge must be calibrated. It's a PITA procedure requiring specific amounts of fuel to be gradually added and measurements taken. It's a three of four step process. My local dealer, who couldn't find his a$$ with a handful of fish hooks made three attempts to get it right. In the end, they were never as close as the calibration I had on the car from the factory.

As for "Miles Remaining", there was a nuance to the AWD models. It seems the shape of the fuel tank would not allow the float to descend all the way down as it would rub the inside of the tank that had to be specially shaped to avoid the front diff and driveshaft. This meant that at some point, the computer had to guess your remaining fuel amount by using its last reading and estimating from injection open times how much fuel you had used since then. If you added a little bit of fuel, but not enough to raise the float, the computer didn't know it, and the calculation was even further off.

Only a German company could come with such a complicated method of doing something that every other car has done for decades.

I hope you have an easier time properly calibrating your 997 sender and gauge.

alexb76

Actually fuel gauge is significantly inaccurate at low fuel levels for C4 cars. This is due to how the fuel tank is positioned across front axle, and that the fuel level sensor is only on one side. To give you an example, I was completely empty, added 5 gallons of gas, and the fuel level barely moved... when it said there's 0 miles left in terms of fuel range, I easily did 60 miles!

MJBird993

You also can't fix stupid.

This is why I don't own BMWs any more.

OP: this exact same thing happened to my buddy with his '83 cab. Sometimes it's smart to always check the obvious things, and we must learn not to trust the gauges. Natch, in your shoes, with that "oil pressure warning" I wouldn't have thought gasoline either.

I had a loaner boxster this week, and as a loaner I was always running it on fumes. I always get nervous when fuel remaining gets below around 90 miles, which coincidently is around 1/4 tank.

bernardbarbour

Wow, well I will have to add this thread over to 6speedonline " Things you don't know about the 996" Specifically I was totally unaware about the shape of the tank on the AWD models. I have a 04 C4S. It all makes perfect sense to me now. I have at some points only put a few gallons in my car when the light came on, just to get me to my favorite gas station in town. Normally I try to run ethanol free gas, while it probably doesn't make a difference to my car, it matters to me that I use ethanol free. Anyway, back to the story. So several times I have put in a few gallons (5) and the gauge would not move at all. Now I understand why. Thanks guys for the helpful tip, and from now on I will just plan on filling up when it get between quarter of a tank and half full.

sjfehr

There's also a certain allowance for sloshing in all models that will mask small changes in fuel level if you only add a couple gallons of gas. It won't immediately register, but the algorithm will eventually recognize it as you drive.

Philster

Just to refresh and add a little detail so others can be warned:

Driving at highway speed. Complete and sudden (not a sputter) power loss. Muscled car off road. Powered off electrics immediately and removed key. Re-initiated start up. "Low oil pressure!!" warnings on cranking.

Almost threw up (that's new detail).

Looked for oil, a smell... anything. Did a possum hitch a ride on my bumper and invite his buddy so they could crawl up and clog both outlets? I looked for that.

Attempted to restart and while cranking got same oil pressure warning message. Was looking for any warning, etc, I might have missed. "Visit service shop'' or whatever that message is did pop up at this point after "Low oil pressure!" Warning.

Fuel? Hmmm... no low fuel light.. hair less than 1/4 tank.

Oil? Its full... according the digital readout I despise.

Called AAA and begged for fuel with tow truck on a hunch (they did NOT oblige). Because with girlfriend on dark road in middle of nowhere in wee hours of night, I waited for the flat bed tow truck and wasn't about to gamble on the fuel thing... which was a wild wild guess at that point. Could not sit there for four hours or more. If I wanted fuel, I needed to request service vehicle first. Ugh.

So... there are ways to calibrate the fuel gauge. I might get into that. Needed car for weekend adventures and there is absolutely no safety issue. Not going to go 150 miles and not add fuel.
[B]
Just keep the fuel gauge issues in mind and don't expect even the slightest of sputters.

And... I had the pleasure of staring at a "low oil pressure' warning after my engine lost power. Yeah... I'll take "out of gas'' over catastrophic engine failure.

.

Chaos

Thank you. I'll keep that in mind with mine!

Minok

How much fuel did you put in the last time before the failure when you filled up?

I ask because with the cars there is also this annoying feature of the fuel level system... when the fuel level is low, and you don't fill up the tank to full (or nearly there), but instead put in a small amount, then the fuel level system doesn't reset, and becomes unaware of the added fuel.. and may well not track the disappearance of that fuel properly either.

I was near empty once, put in 2 gallons once to get me back to my regular station, but that 2 gallons didn't register on the car's system. Though that could be the complication of the Targa 4 fuel tank, discussed in another post.

Philster

I always fill up... but the AWD models do not register fuel when it gets low because of the tank shape being split by a hump from driveshaft.

As the tank drains, the sensor/sender isnt doing anything when it gets low. The comp is doing math to figure out what is left based on various parameters.

Adding a few gallons won't register and might actually be mentioned in owner manual.