CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

1998 Subaru Forester Smells of Fuel

Okay, I’ve been trying to diagnose this problem for ages. Whenever I top off my tank with fuel, the garage smells of fuel until I use up about a quarter of the tank. The smell stays mostly outside of the car. So far I have replaced the drain filter (a few years ago), fuel filler neck, hose leading from the filler neck to the tank, and had the system pressure tested. I’m fairly certain it’s not the tank because the car has been undercoated since new and my mechanic saw no signs of a leak when he replaced the rear crossmember recently. My next guess is either the gas cap, the charcoal filter, or some hose leading to/from the charcoal filter. This one really has me stumped because every time I think I’ve solved it… it turns out I haven’t.

John

If you top off your tank beyond the first click, then I’m absolutely certain it is the charcoal canister, and it is most likely saturated. When this happens, the fumes escape through the atmospheric vent. This only happens when the canister is saturated with fuel fumes or liquid gas from overfilling the tank.Try not filling the tank past the first click. It will take time for the canister to purge itself of these fumes, but it is cheaper than a charcoal canister.

The only way to prevent this in the future is to stop filling the tank at the first click.

There is also a chance that the fuel sender seal is leaking. If you top off, fuel will seep past the bad seal. If you don’t top off, fuel will stay below the bad seal.

The scenario I described often is accompanied by an evap fault code.

Is or was the check engine light on.

“System pressure tested” means exactly what?
Are you saying that a mechanic used an evap/smoke machine to test the integrity of the system?

Thanks for the replies so far everyone.

@BustedKnuckles
I would gladly take your advice, no question. The problem is, I live in NJ and we’re not allowed to pump our own fuel. eyeroll
I always pay cash (since it’s cheaper than credit) and I’ve tried asking the attendants not to cram extra fuel in. They either ignore me or give me a hard time because they’re too lazy to make change anymore. When I am out of state, I always try not to put extra fuel in once the pump has kicked off. At the absolute most I will round off to the nearest 25 cents.

@db4690
My mechanic says he performed two tests. The first was the smoke test you mentioned (he saw no signs of smoke outside the tank) and a pressure test which the system passed as well. Recently, however, I heard that a vacuum test would have been more accurate.
Could you give me a rough idea of where exactly the fuel sender seal located?

"I live in NJ and we're not allowed to pump our own fuel."

Couldn’t you thwart that by specifying a dollar amount that will not fill the tank?

Probably is the canister but I have had the top of my tank rust and leak. Same symptons. Only leaked after I filled it and just enough to smell the garage up. Couldn’t see it because it was on top of the tank and don’t believe it was enough to leak on the ground. I finally crawled under it and reached on top of the tank and could feel how wet it was with the mixed in sand and salt. Just saying to make sure and it would not be uncommon in NJ.

“The problem is, I live in NJ and we’re not allowed to pump our own fuel.”

That situation is a problem only if you allow it to be a problem.
I also live in NJ, and I almost always am able to take charge of the situation. It just requires the right attitude, plus a refusal to be intimidated by the attendants.

I do this for two reasons:

The previously-stated reason of not wanting the tank overfilled.
Not wanting the attendant to drop the gas cap (on its tether) onto the fender, thereby scratching the paint.

Here is my routine:

Before entering the gas station, I release the gas-filler door.
As soon as I stop the car, I get out, remove the gas cap, and hang it from the hook that the mfr provided for that purpose in order to keep it away from the fender.
When the attendant approaches, I hand him my credit card, and tell him to “fill it regular”.
I stand next to the car, and as soon as the pump clicks “off”, I remove the nozzle and put it back in the pump, while waiting for the receipt to print.
If the attendant is actually present when the pump clicks “off”, I simply say, “That’s enough. No more”, or if he is Hispanic, I say, “Bastante, no mas”.

I have NEVER had an attendant react badly to my “take charge” approach, and–in fact–most of them thank me for finishing the process and not making them walk back to my car.

So…stop being a wimp.
It is your car, and you have a right to prevent someone else from damaging either its fuel system or its paint.
Or…you can just sit passively in your car, and allow the attendant to do whatever he wants to do.

Trust me–Nobody has ever been arrested in NJ for taking charge of the fuel-filling process.

@WesternRoadtripper
I would definitely consider that. However, my fuel gauge has become unreliable over the past few years (just another issue I have yet to address). Therefore, I reset my tripometer at every fuel stop. I know I can go 350 miles before I have to start looking for a fuel station and the only way to be certain of that is to start with a full tank. Otherwise, yeah, I would totally give the attendant an amount to stop at.

@Bing
I’ll have to look into that. Even with the undercoating, my frame has started to rot in spots thanks to how horrendous the roads are in the winter, so it’s not entirely out of the question that the top of the tank may be leaking.

@ Everyone else (I won’t name names)
I posed my conundrum here on Car Talk because I wasn’t getting answers anywhere else. I didn’t expect to be harassed about how I care for my car or to be called a “wimp.” If you don’t have anything to contribute to the topic (not just mine, but any of them on this site) or just don’t have anything nice to say, don’t waste our time! I do most of my own car maintenance so don’t treat me like an idiot. Again, thank you to everyone who has given me good, sound advice so far. To the few others who haven’t been so helpful, well, I’ve said what I wanted to say.

John