Gas smell

[AustinGT350]

98 Cobra, race car (factory tank), gutted, no cats/emissions, etc

Last year, I always had a gas smell in the car that would show up after a few laps. I just went with it, assuming it was a weird vent issue. Over the winter I cut off my mufflers (turn downs right before the tank), and welded some resonators on it and didn't have time to put a set of turndowns/dumps back on.

First race of the year was last weekend and I ended up getting a mechanical because the car was spitting fuel on left hand turns (the gas smell was really, really bad and it was pooling fuel in the trunk). I got to talking with some of the guys, they brought up a good point, the exhaust is pointing right at the tank and it's heating the fuel in there and pressurizing it. I got a hold of a set of turn downs and clamps and called another SN driver who told me to unclick the gas cap 1/2 turn. I also redid the tubing for the vent (which is like 9" of tubing that feeds to a hard line that vents into the gas filler door).

The smell is better, but it's still obvious. The director for the weekend had his eyes on me after that and would come and smell my car afterwards, and continued warning me. The other SN driver (who had a similar issue, and still does slightly), told me I need to get the exhaust further away, but I'm wondering if there are other options as well with these cars. I can't find anywhere in this car where it's venting back inside the cabin, I would like the smell gone. After each race, checking the cap it would have some fuel on it (from slosh I guess) but no pressure build up or anything.

Am I at a point where I need to add a canister back into this thing? Or would a new vent for the tank work?

Any thoughts are appreciated, sorry for the wall. I'm trying to give you guys plenty of info.

 

[johnjamesmiller]

I’ve heard of that gasket between filler neck and tank going bad. 24 hours of lemons forums might have some more advice. Lots of crown vics in there that may have similar issues.

 

[blacksheep-1]

that would be the first place I would look as well, the filler neck apparatus..
FWIW the old 69 Shelbys used to toss a fireball out the back now and then, seems the rear exit exhaust, fuel cap and vent systems would act up when the Kamm style rear spoiler would cause the vapors to accumulate at the rear of the car.

 

[Jules98GT]

I currently have the same issue right now, have been working on it for about a week. Showed up after my 2nd autocross event this year.

 

[AustinGT350]

For anyone curious, I have an update that seems to work for the most part but I will make it better over the winter.

After what I thought was a solid fix, filling random holes in the filler neck area and making a block off plate that was sealed to keep fuel out, I had the issue again in Hastings where the trunk took on fuel and the smell was awful.

I pulled the check valve from the vent (I assumed it was getting stuck shut), ran a much longer hose from the vent up inside the trunk, made a few loops and fed it outside the car. That way at least I could tell if it was making it's way out of the cap, the old vent tube fed into the fuel door.

Smell is 100% gone, and verified by my wife who seems a lot more sensitive to that sort of thing than I am. I was still pushing fuel out of the tube and got a warning from tech, for a quick fix I hose clamped an old stainless bottle under the car and that actually did catch fuel, but I had a misfire issue and I thought it may be from the tank being over pressurized (the hose was slightly kinked).

The fix over winter at this point will be to install a coolant overflow that feeds from the bottom and vents out the top. I'll stuff a few pieces of steel wool inside the canister for baffling and run a hose up very high inside the cabin, then back out of the car where I won't get any fuel smell.

It's been a dumb road to get here but if anyone else is having these issues, it may be a decent fix.

 

[302BOB]

FWIW......I had a strong gas smell in my '87 Olds Cutlass many years ago.......It turned out to be a bad fuel pump............................