Fuel smell troubleshooting help.

Just picked up a (new to me) 2002 996 C4S and i�m having a little trouble finding out how to troubleshoot a fuel smell coming from the car. I�ve searched through quite a few threads and haven�t been able to find something that�s really fitting my issue. Car has 92,XXX miles, and no noticeable fuel smell while driving, but after being parked for 15-20 minutes in my garage, the garage smells pretty badly like leaking fuel. I replaced the gas cap with a brand new OEM one, didn�t seem to solve the problem. No trouble filling up (rules out bad charcoal canister?) and it�s not dripping any fuel at all on the floor. (Id be much more concerned if this was the case). After leaving the car overnight in the garage with the fan on venting out any smell, there�s almost no lingering smell coming from anywhere around or near the car. Super faint around the gas cap area but you wouldn�t notice it at all. No smell in the frunk/interior or around the engine area, definitely smells like it�s coming from passenger side front area. Because the smell isn�t lingering, and presumably is just fumes venting, not an actual fuel leak or spill, where could this be coming from? Any simple troubleshooting steps I could take or suggestions are much appreciated!

Just a thought....the cabin air intake is located on the passenger side under the cover next to the battery. Under the battery tray is the fuel pump and hoses. Remove the battery, battery tray, and make sure there is not a loose hose or vent hose on the fuel pump.

Fuel Sending Unit. For the C4S remove the black hat in front trunk and check for cracking and fuel leaks. Here is the Part. https://www.sonnenporscheoemparts.co...g2LWdhcw%3D%3D

When I had my 2002 C4S I made the mistake of over-filling the gas tank and in doing so the fuel cannister must have gotten some raw fuel inside rather than just fumes. Took quite some time for the fuel odor to go away...…… With 92,000 miles, is the current cannister the original?? All the other diagnostic suggestions seems very logical and may result in finding a small leak but if you mistakenly over-filled the take due to a bad shut-off valve in the gas station filling hose it may be as simple as waiting for all the fuel to evaporate. Good Luck Demosan

I replaced the gas cap when I had a similar scenario. Hoping yours is as easy a fix.

Had similar issue which is intermittent. By your ID, guessing you are in CO. Something to do with the evaporative system and altitude. I had a post about it a while back. Don't think there is a cure if it is the same as mine.

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Thanks Demosan! This may be it... how long did it take to fully evaporate the smell? I drove the car 400 miles home from where I bought it, filled up twice on the way back and noticed it when I got the car home. So roughly speaking, it�s got about 200-300 miles on it since the smell started? Dealer didn�t mention it, neither did the guy that did the PPI (doesn�t mean it wasn�t happening before) but definitely could still be the case. Appreciate the feedback!

Devin, my recollection was the fuel odor went away completely in a couple of weeks. In my case I can't remember if the "over-fill" was in the summer or cooler weather. If possible, I would leave the car in the sun for a day or so rather than the garage as I believe it would accelerate the evaporation of the excess fuel if that is fact the source of your problem. Good Luck!! demosan

[SOLVED] Following up on this! Was traveling for work, so didn�t get a chance to investigate until last night. Popped off the �top hat� to take a look at the fuel sending unit and those connections since that�s a good place to start. Found a few things - a sizable puddle of fuel (see photo), and the large black ring that seals the fuel sending unit was loose? You can see in the photo, it moved about 2 inches from where it was originally sealed. I have no idea how this would come loose, other than it was slightly loose already and the pressure change from driving it from nearly sea level to 6400ft elevation caused it to loosen slightly with the usual road vibrations. Tightened everything up snug, re-seated all the connections and cleaned up any remaining fuel in the dish on top of the sending unit, and the smell appears to be gone. I wasn�t able to get all of the spilled fuel out of every nook and cranny, so there�s an ever so slight smell coming from under neath the gas cap in the FP wheel well, but the smell is no longer noticeable when parked in a closed garage after driving. I�ll update if anything changes, but hope this helps someone else experiencing an issue similar!

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Thank you so much for this, I was freaking out(just picked up my 996 c4s). Did you had to replace that connector of found a way to ensure it won't come off again? I'm worried that a spark can be triggered since the battery is right behind it and there are some electronic components inside that cap. There was a little pool of fuel around the black connectors

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Hey 996chapin, No I was never able to find out specifically what part that was. I called 4 different Porsche dealerships asking about the part and nobody could find it, all I could find was the company that makes the part is a 3rd party �quick fitting� manufacturer that never responded to my emails or calls. I don�t believe it was the quick disconnect that failed, it was the actual fuel sending unit, and after replacing the unit on mine, the issue went away completely and there is no fuel leaking out there at all.

The nipples on the fuel sender (combination of fuel level sender, fuel pump and filter on a C2) will get brittle and crack. I had a fuel leak and found the same issue; fuel pooled up on top of the sender assy. I too though it was the connector as I could wiggle it and get residual pressure to leak past the o-ring. However, upon closer inspection, I found hairline cracks in the nipple. oReplaced the sender and pump assy and no leaks since. BTW, fuel pump failures are common on high mileage cars and can occur without any symptoms to ward you. So I would replace the whole thing and be good for another 20 yrs.

Thank you both for your responses, I did noticed the gt2 fuel sender unit does come with what looks like metal sockets instead of plastic, I've searched the web for a similar one for a c4s but they all have that plastic nipple... I already ordered a new part and will be replacing on Monday. Cheers!

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So...I was right in Post #2? Huh...funny how nobody said so....

Yes! I just went ahead and read to the one that stated [SOLVED].

I had same problem. 93x miles. Pulled off the �hat� in the frunk, had a friend start car and saw gas coming out of sender unit around the OUTLET nipple. Photos show cracks that actually ran up the nipple. Easy fix: old unit out, new one in. 1 hour. Disconnected battery BEFORE job. This saves fuel level and did not need to recalibrate.

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Have the identical problem on my (RHD) C4S. However don�t know what you mean by the �top hat�

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The "top hat" he is referring to is simply the "white part" you see in the picture...