cringely

I just bought a 2002 996 and have a question about the gas tank and gas gauge. The book says the gas tank volume is 16.9 gallons. If I drive until the miles to empty goes to ~10 miles left (implying a bit under 1/2 gallon left in the tank) and completely refill the tank, I end up putting in ~14 gallons.

Does this mean,
1) my gauge/display isn't working correctly (if not, what do I do about it?),
2) that EMPTY really means there is as much as 2.9 gallons still left in the tank, or
3) something else?

4) also, the automatic shut-off on the gas station's nozzle shuts off the fuel flow after a few gallons (as if the tank was full) and I have to restart the process in order to completely fill the tank. Is this a "design" feature of the 996 fuel filler pipe or something unique to my car. This has never happened with any other car I've owned.

I'm still getting used to the 996. My previous car was a 1980 911SC with a 21 gallon tank that I could go 400 miles before refueling (500 on long trips). The 996 seems to give me a 300 mile range (obeying the fuel gauge/display) for around town driving. No long trips yet, so I don't know what range I could get on a cross-country drive. I do plan to drive from San Diego to Ohio at some point, so this question isn't just academic. Any comments would be appreciated.

P.S., I asked this on the "Things you didn't know about your 996" thread, but haven't gotten a response, so I thought I'd try it as a separate thread.

WalterRohrl

My 2002 that I recently acquired as well does the same thing in regard to range on the trip computer vs. what actually goes in the tank. Too scared to really test it... ;-)

My fuel flow does NOT shut off like yours. If it's a feature it must have been a Porsche option that cost the original owner many dollars that my guy skipped... Actually on my third ever tankful, the nozzle NEVER shut off and must have pumped about 3 gallons all over the gas station grounds....

I bought mine in NJ and drove it home to CO. Average MPH was 70, average MPG was 27.2 if that helps any.

mmahon04

My 1999 has the same "problem," but upon reading the owners manual awhile back, I found it has a reserve capacity of 2.5 gallons, if I remember correctly.

Essentially, 14 gallons will get you to "Empty", while you still have that reserve capacity of 2.5 gallons.

- Matthew

ChristopherG

About 50 miles worth of fuel beyond empty seems to be about the average reserve capacity.

Imo000

50 miles after the light comes on or 50 miles after the needle bottoms out?

ChristopherG

After the warning light.

Macster

50 (at least) miles after the light comes on though YMMV.

My 02 Boxster's low fuel light came on the other day in Santa Clara and I drove all the way to Livermore, over 50 miles.

At some point maybe half way to my destination the gas gage needle was down on the empty hash mark.

Made it to 1st Street exit (my exit) in Livermore and as a "test" on the off ramp I braked hard, then when the light changed accelerated hard concurrent with making a sharp right hand turn off the off ramp onto 1st Street to see if the engine would cut out from low fuel and there was not any a hint of any cut out.

Without any drama I drove the block and half (down hill which is why I was not too worried about the engine cutting out...) to my favorite Shell station (hey! how about those gas prices? Under $4/gallon!) and put in 16.02 gallons of gas in the 16.9 gallon capacity tank.

That's as much as I have ever put in the tank. Previous "record" was 15.6 gallons.

b8_rdc

Well I personally wouldn't go for any "low fuel records". All you are doing is running the pump into maximum sediment mixed fuel and minimizing the cooling effects of the gas around the pump itself.

Given the cost of the pump and fact that filter isn't serviceable on most 996, bad idea....

Pac996

If after filling up your gauge does not show full but between 3/4 and full then the battery was disconnected at some time when the tank wasn't full or something like that. Porsche can recalibrate for a small nominal fee compared to the price of gold. I believe there is a do it yourself on this fix but eh I might be wrong.

If the gauge does read full WITHOUT making the big mistake of topping off the take doing multiple run till shut off of the gas pump then its standard data. Don't be topping off filling the tanks filler neck. You'll slowly get gas in some carbon filter related to the overfill and get a check engine light.

Or your car has the new gas tax installed taking a couple gallons per fill

Even aviation gas gauges are only required to show if there is fuel not exactly how much. Just to register there is fuel.

Hurdigurdiman

First off...U S Gallons and Euro Gallons are differant sizes. I am pretty sure that a reprint of the Porsche owners manual was never on the agenda for the U S Market on these cars. Solve all your problems and fill it when the tank hits a quarter full. Why worry on how much to the gallon you are getting. Keep pumping until the pump cuts off and thats it. What it says on my tank is NEVER FULL. Hey do i care? Hell no, I fill it again when it hits a quarter full mark and drive it like I stole it again. If you have to wonder how many miles to the gallon you are getting then you shouldn't be driving a car that only does 16 miles to the gallon around town or under 'spirited' driving conditions. And 50 miles to the gallon out of gear free wheeling down the side of Mount Everest lol.

Quadcammer

You really don't think the sediment is getting well mixed when driving? Not to mention, I've pulled tanks on at least a dozen cars, and never found any meaningful sediment or clogging of the pump's sock filter. Furthermore, primary cooling of the pump is done by the fuel flowing through the pump. Yes, on return style fuel systems, that fuel will heat up, but it should not be that significant unless you are extemely low. I'm not sure if the 996 is returnless or not.

I haven't even the slightest clue what you're talking about. You are pretty close to going on the ignore list.

Macster

I'm not suggesting a low fuel level contest. It just so happened given the circumstances of the other day I drove the Boxster longer with the low fuel light on than I have and harder than I would normally drive and then got caught in the blankity blank new outlet mall traffic on I-580 (don't ask...) and the fuel level got run way down lower than it ever has before.

I'm usually filling up the tank even before the low fuel light comes on but once in a while...

While there is sediment present the fuel pump housing is the fuel filter and has plenty of capacity and none of this gets past the filter. (I have a pic of my Boxster's old pump showing the filter portion of the housing.) The fuel system is a returnless system and the pump doesn't run as hot as it would in other types. The original fuel pump lasted to around 200K miles and I expect its replacement to last that long as well. And as further evidence the filter is good the injectors are original and have over 260K miles on them.

Even so, I will probably not ever run the tank as low as I did the other day.

Hurdigurdiman

OK Quadjammer. Did you know that there are over 24.019 UNITED STATES Gallons in 20 United Kingdom Gallons or European Gallons. Seeing as how the Porsche is a European car and not an American car the owners manual is written with referance to Imperial Gallons. I doubt that the owners manual would have been reprinted to suit the United States Gallonage of the Porsche 996 as most of the cars go world wide anyway. Here is a link to explain so I dont go on your ignore list. Just thought I would throw a wrench into the workings lol.
https://www.google.com/search?source...38Iz0jD4&pbx=1

Ubermensch

Do any other countries use imperial gallons other than the UK? Most of Europe is on the metric system the last I checked. So yes, I think they wrote the manual for the US market and not the UK market since one is roughly 5x the size of the other.

Hurdigurdiman

The UK is in litres now but still has so many litres in a gallon. 4.54 litres = One Imperial Gallon..They dont measure in Gallons anymore. None of Europe does anyway.

3.78 litres = one United States Gallon. By the way the European Continent is in litres and in Europe when they talk Gallons they certainly do not talk U S Gallons but Imperial Gallons. And another BTW... The United States is approx 50 times larger than the UK not 5 times larger. So lets say that the book was wrote for the United States with the United States Gallon in mind... end of story. I would like to compare an English speaking LHD owners manual to a RHD English speaking owners manual just to see if they say a differance in the gallonage that the car tank holds. Hey all of this is 'mint imperial' ( cockney slang for immaterial) so lets forget it lol. I should never have even mentioned about the imperial gallon. Now every body is confused.