How much fuel is actually left?

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.

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.

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

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

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

After the warning light.

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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.

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....

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.

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.

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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.

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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.

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

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.

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.

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um, since imperial gallons are more than us gallons, you are basically making the opposite point. If the gauge read empty and he filled it up with 14 us gallons, that would mean the reserves or whatever is actually bigger than the 2.9 gallons that one would think are still in the tank. Not to mention, I think porsche is smart enough to adjust for these changes in the owners manual.

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Yep. The answer to #4 is in there. I had to lose a whole saturday reading through that thread. Turn the nozzle upside down when you're filling your car. It's a trick that apparently works on all 911s, though I've never confirmed.

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Confirmed. I do it every time.

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I haven't pulled out my owners manual, but the original (US) sales document (MKT 001 00001 03 E/US) �2002 states "Fuel Tank Capacity: 16.9 gal (64 liters)", which makes the 16.9 gal US, not imperial gallons. If anybody has a UK 996 owner's manual or original sales brochure, I bet the Fuel Tank Capacity is listed in liters. Thanks for the all the responses to the original post. I now know that (assuming I want to be brave and foolish ) I have to find a gas station within ~60 miles after my "miles to go" goes to zero.

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The CA fuel nozzle vapor containment "condom" is partially to blame for the frequent shutoffs. If you turn the nozzle upside down it helps.

My original owners manual for my 1999 C2 coupe has part number WKD 996 121 99 and is dated 7/98. It also states it was printed in Germany. On page 184, under the title Capacities, Fuel Tank, "Refill volume approx. 16.9 U. S. gallons/64 liters, including approx. 2.6 U. S. gallons/10 liters reserve." All of the data on that page clearly states that all volumes stated in gallons are U.S. gallons. Also, smaller volumes than 1 gallon are stated in quarts (and fractions to the nearest 1/10th quart), AND liters to the nearest 100th/liter. Hurdi, your arguement about Imperial gallons does not apply to the U.S. spec or delivered cars. Please consult your owners manual for accurate info. To all, your gas gauge may not indicate absolutely full, even when your tank is absolutely full, and your gas gauge may show empty when you are actually just starting the reserve portion of the the tank. Obviously, Porsche intended to give you some wiggle room to find the proper brand and octane rating of gas for your car when the tank was getting very low. Intentionally driving the car into the empty warning light as a regular plan does nothing to save you money on gas unless you are hoping to find that one gas station you know where the cost is 2c per gallon cheaper. Really? And you bought a PORSCHE?

On the 996, it is a known issue that if the evap canister on the tank fails, it becomes more difficult to fill the tank, particularly if the tank is depleted down to a low level. If your car has over 70k or so, it is possible that it is on its way out. There is a TSB on this. Also note that Porsche has stated (in the owner's manual IRRC) that if you draw the tank down below 1/4 tank and then don't put the equivalent of ~8 gallons in, the gauge will read completely incorrect until topped off...

When the owner's manual for my 996.2 said there was a reserve of over 2 gallons, I figured that that was below a reading of empty, like it is on all of my other vehicles. Nope. I ran out of gas for the first time in over three decades of driving when the gauge hit empty. Due to the geometry of the fill tube and tank, when refueling, the automatic shutoff value kicks in really easily on the 996. This didn't happen on my 1986 911 Carrera. This regularly happens on my 996 when the tank had only been filled to half, so no, I don't stop there. Slowing down the fuel delivery rate helps, as does rotating the nozzle like Targatoo mentioned. Someone commented on crud in the bottom of the gas tank. I replaced my dead fuel pump myself this year. It is mounted on the inside bottom of the gas tank. I had to carefully scoop out a few gallons of gas to reach the pump. There were a few chunks of crud drifting around on the bottom of the tank. I could only grasp and remove a few pieces with gloved hands and awkward access.

You think keeping the fuel at a sufficient level prolongs the life of the fuel pump? Not sure if it's a myth. I personally like to keep mine over halfway

My fuel gauge is wrong the other way around - never reads much less than half a tank - before you run out of gas... Goes all the way up when I fill it. I usually refill it right around 200 miles to be safe. It generally takes around 11 gallons of fuel after I've driven 200 - 220 mi. so, with the 5-6 gallons left I should get another 100 - 120 mi. giving a total range, full to empty of 320-350 mi.

I'd like to clarify something... (on a 99 996 if that makes a difference) So when the gas gauge hits about the 1/4th area, the orange indicator light comes on and the dash says something like 60 miles until empty... So once it says like 5 miles to empty, is that the end of your reserve tank? Like you literally only have 5 miles until it dies... Or is it you have 5 miles until the 2.5 gallon reserve tank kicks in and you're running on that. Just curious, and wanted some clarification.

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My Turbo is a bit different -- the tank is sort of divided into two -- but that miles remaining is just a number, an estimate. But I take the miles remaining as something close to reality all the same and interpret it as based on how I was driving how many miles are left, how much gas is left, in the tank, if I continue to drive the same way as I was. However, when the low fuel light comes on and I pull up the miles remaining display I can sometimes have the miles remaining number go *up*, that is increase, if I drive like a high miler. BTW, with the fuel pump in the tank systems I've always tried to make it a habit of avoiding driving the car with the fuel level too low to avoid possibly running the pump hotter than it would get at least partially submerged in fuel. I think this running the fuel pump too warm is a valid concern as I note my 996 Turbo has a fuel cooler that is cooled by the A/C when the A/C is on. Granted the Turbo fuel system requires the fuel pump run all the time to keep the siphon jets working but every fuel pump is just an electric motor and with no air circulation has to rely on being cooled to some extent by the fuel in which it is exposed to. From examining my Boxster's fuel pump housing it looks like some fuel is directed to flow around the fuel pump body proper to I suspect offer cooling when the fuel level is low enough the pump is not submerged in fuel.

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C4?

"C4?" You betcha!

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Your float is probably stuck then. Like the Turbo the C4 has a saddle tank to fit over the front drive train. Ours used to get stuck all the time, though it was the opposite of what you describe (would never register full). Techs always told us it was cause we'd run it down too low. It hasn't happened in a long time and I've been better about filling shortly after the light comes on rather than my historical "see how far I can milk this puppy" approach (I've only run one car out of gas doing that).

In ~30 years of driving, I've run out of gas exactly once...this is when I came to understand that whatever you needle says when you're below a quarter-tank is your C4's best guess...and my C4's guesses are about as reliable as the 10-day weather forecast...

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Stuck on what? "In ~30 years of driving, I've run out of gas exactly once...this is when I came to understand that whatever you needle says when you're below a quarter-tank is your C4's best guess...and my C4's guesses are about as reliable as the 10-day weather forecast... " ^This^ is why I always zero the trip odometer and refill when I've driven 200 miles or so...leaves me a pretty big buffer

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LOL. I do the same.

"How much fuel is actually left?" I suppose it's an innocent enough question. I long to live in a world where this would be important. As an apparent simpleton, I've always just, you know, filled up when the fuel level was low.

I have the same issue with my 02TT, whenever I am near the bottom 1/8th I always refill with only 14 gallons. If your gas gauge is not reading correctly I found filling the tank and then disconnecting the battery for 10 min should fix the problem.

The saddle-tank gauges will also misbehave - albeit only until the next fill - if you disconnect the battery when the fuel level is low. This is my car's equivalent of "dunno, bud...you're on your own." As far as the 200-mile rule - as you know, your mileage varies DRASTICALLY depending on how you drive. I'm definitely a foot-in-it kinda guy, so going by mileage is sketchy at best. I just fill it up at a quarter tank...

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No idea. Just what the Tech always told us. It hasn't happened again since its been out of warranty so I've had no cause to question it. I do it to track the miles, but yeah it is a good indicator if the fuel gauge is playing up. I've run out of fuel twice. Once in my dad's pickup because he didn't bother to tell me that gauge was messed up and 1/4=0, so that wasn't intentional or irresponsible. The second time was in my Escape and that was due to me pushing it too far. Engine cut out just as I was stopping at the pump.

"As far as the 200-mile rule - as you know, your mileage varies DRASTICALLY depending on how you drive. I'm definitely a foot-in-it kinda guy, so going by mileage is sketchy at best. I just fill it up at a quarter tank... " 120 - 150 mi. buffer would be pretty difficult to use up by driving hard...I'd think the IMSB or one of the cam chains or ________ (fill in the blank) would give up before running out of fuel... As for making it to 1/4 tank...uh, no I'd be empty first.