I have one. It kinda picks up everything. I dial the sensitivity in, but then it reads positive at every gasket and gaiter….
It didn’t seem very conclusive. Perhaps I should open up that baffle plate and air it out for awhile and then make another attempt.
There’s something wrong here. The detectors reaction should be progressive as the sensor head approaches a stronger concentration of fumes. You are looking for the strongest response - not just a “positive” response. Mine will pick up fumes permeating through Gates Barricade hose, but only at a low level - plunge it into the tank filler neck and it goes wild.
Frankie
Frankie
Filled up the tank. Smell is back. I could not get so much as a whiff of fuel from underneath the car, after parking it all day in my garage at work, so I’m pretty certain it’s gotta be the tank.
Since the tank is full and the smell is as bad as its ever gonna get, I’ll have a go, one last time usign the sniffer to see if I can find anything. I can really only reach one side of the tank seam, I guess I only get about 35% of the probable area of failure for investigation.
I have to decide whether I want to do this myself, or take it to the shop…
The flow and return pipes under the car are metal for the most part but run as hoses over the IRS to where the fuel tank connections are made as Kirbert has said above. Worth checking these with the sniffer but unlikely to be the cause of the problem if there is no smell under the car.
If the trunk smells when the tank is more than half full that does suggest a leak part way up the side of the tank, but are you sure it is the fuel level that brings on the smell rather than the action of filling? If the latter, it may be a faulty gaiter (I know you have already replaced it - just saying…)
Only other item not mentioned so far is the filler cap seal. Worth checking.
Frankie
there seems to be several suspicious smell possibilities… I did all kinds of repairs… experiments etc… lined tank… eliminated sump tank… new hoses … filler seals even temporarily by passed accumulator above tank… still smells… gave up looking cuz after driving a little the smell goes away… got tired of fiddling with it…
Scrimbo, that is cause for concern to me.
If I end up replacing/coating the tank and the smell is still there….I will not be a happy camper.
Frankie,
I do not know if it’s the act of filling that causes the problem, but it’s an interesting theory to test.
What would happen if I cut that gaiter away completely? I could then monitor what happens at the filler neck when filling? Maybe throw some baby powder around there to see if there’s any evidence of a leak?
No! Strip out as much of the trunk trim as you can for access to the filler neck area and tank seam so you can use the sniffer to best effect. If you can’t find the cause and decide to take it to the shop don’t tell them what to replace (you don’t know) but instead ask them to trace and diagnose the cause of the fumes. Then take it from there.
Frankie
I don’t think I know a shop that I would trust to spend the time to diagnose. Smelly trunk, replace the gas tank. That’s all I would expect.
Maybe I’ll stop by my local shop (not the Jag mechanic) and ask him what to do…
Interesting development.
After my most recent adventure in the boot, replacing the last rubber hose I missed the first two times I was in there, then blowing compressed air into the evap/charcoal canister hose, I thought that the fuel smell did not return as strongly.
So when it was time to tank up, I only filled it up with 10 gallons, about 6 gallons short of a full tank, according to my pretty darn accurate trip computer.
I still noted a smell, so I bought a $60 ozone generator on Amazon. I ran it for about 20 minutes and the smell is gone. It was the carpeting in the trunk that had trapped the gas smell! So I have a clean slate. It was the carpeting in the trunk that had trapped the gas smell!
So far I haven’t refilled the tank, but the car has no fuel odor in the car.
I will fill it back up to the same amount I did last time, 6 gallons short of full to see if the odor comes back. If not, I’ll go hog wild and fill it to the max after a few days of driving. Will report back.
I’m hoping to prove that the tank itself is indeed fine. There was either (1) a clog in the evap lines, which regardless, I will do more thorough investigating, including removing the hard pipes and checking them for any clogs, OR (2) a problem at the filler neck connection somewhere. I am concerned that if I fill up the tank, the fuel may be leeching out of the gaiter area. I have very recently replaced both that gaiter AND the o-ring that connects the two pipes…I’ll have to investigate that further as well.
Learn something new every day! Now, can you please explain why prices on ozone generators range from $40 to $1000?
would the smell go away if you left the carpet out for a few days and check for odor in trunk before replacing same
No. There’s a mat under the fuel tank that would probably not air out. I let it run for less than 20 minutes.
As for the cost difference. I know some of it has to do with how much output the unit can put out. Some of these things are apparently sized to work in homes. For cars, you would only need the smallest of the small. (That’s what she said)
In case this helps anyone in the future.
The hard pipe that runs alongside the fuel tank and pops out underneath the car is a 3/16” pipe (CBC9539)
I’m going to try and bend some new pipe and replace it. I think I’ll upsize it because….
The hard pipe underneath the car is 3/8” hard pipe.
Not sure why it has to be so small alongside the tank. The hole can easily handle a 3/8” pipe just as well. It should make the rubber hoses needed to connect these sections of hard pipe much easier to keep track of.
I pumped in 6.75 gallons this morning…so basically with six gallons short of a full tank, there’s still no smell.
I’m going to fill up the tank all the way before I head to work tomorrow and see what happens then. I’ll keep everyone updated.
I don’t understand why your cat has that persistent problem, VK. Superblue does have some gas fume “issues” shortly after I fuel up (no matter how little I put in, it seems). I can smell them in the cabin, but only for about the first 10-15 minutes of driving - after that, they disappear completely. 
She’s done this, IIRC, since about day 1 of when I bought her (5 or so years - 25K or so miles) ago … I’ve just learned to live with it …
I filled up the tank this morning. No smell.
I believe I may have resolved this problem sooner but was unaware because the residual fuel smell made me believe it was coming back, so I don’t know what it was that I did that fixed the problem.
The good thing is that the fuel tank will not need to be pulled!
Thanks to all for the help!
Spoke too soon. Smell is back.
I think this means that the tank, in general is good. I either have a problem at the filler neck, which is where I’m heading now, or the tank had imploded somewhat. That could explain why my fuel sender couldn’t show a full tank.
I think the plan is to remove the gaiter and fill up the tank and see what happens? Watch with a camera, maybe feel by hand?
I suspect my passing smell issue is possibly some tiny cracks or holes in the filling tube (gaiter?) that allow tiny amounts of fuel (i.e. drops) to fall down inside the boot on the fuel stream’s way to the tank. After several minutes of driving those fuel “drops” dissipate/evaporate and no more smell. ?
There is a sealing ring CAC7509 between the tank and filler neck. If that is missing/has become dislodged fuel may escape when filling or tight cornering with a full tank. Worth a look.
Frankie