Mysterious ON/OFF Fuel Smell in Cabin

[SFBayQ45]

I have an frustration fuel smell situation. On it's OFF day, I don't smell gasoline in my cabin. On its misbehaving days, I would get this annoying lung-killing/brain-cell-killer/strong/pungent/overwhelming (running out of appropriate words) fuel odor in the cabin that is no different than (if you can imagine this) being in the gas chamber.

I've brought this to the attention of my trusted mechanic/technican/off-duty mechanic friends/dealerships, and none of them can find the culprit. What appears to be happening is that whenever I bring it to a shop, the gas smell just simply disappers or slowly go away to the point where they can't trace it. I've had the Consult II hooked up previously and there isn't any codes showing up bad. So what could be the problem? The most senior tech at the dealership couldn't find out the problem, and sure enough when I drove it off the lot it did not give any smell. Now (one week later) the problem comes back with this headache-of-an-odor that is giving me a terrible headache like sniffing 90% octane and 10% oxygen everywhere I drive. And I noticed that the smell comes strong from the rear passenger side (right next to the gas tank opening). I did noticed that filling up the gas tank again remove the smell for approximately a day. So my question is, it there a mechanism next to the gas tank opening that opens or closes the gas tank vapor? Could it be remotely affected by certain motions I make when I insert the nozzle into the tank? I know there's that small stainless steel lid that open/close whenever you insert a nozzle into the gas tank and I make sure that it closes when I remove the nozzle, but are there any other closing mechanisms inside the gas tank itself that I'm not aware of which aren't closed correctly and is leaking fuel smell into the cabin?

Here's a word-for-word description of the diagnotic performed by the dealership's most senior tech regarding this fuel-smell problem:report-line3: filled gas tank full and removed trunk carpet to inspect gas tank, however no leaks found in trunk; all lines are tight; rocked vehicle up and down and found no leaks; inspect gas cap and tested and passed; inspected under hood and unable to see any gas leaks around vehicle injectors; fuel filter and lines are OK; no gas smell dected; racked vehicle and found all metal lines from front of vehicle to rear are OK; no signs of any gas leaks; fuel system seems to be in good condition.

PLEASE HELP!!!

[qship96]

my 96q has the same issue!my guess,bad o ring seal after pump was replaced last year-smell is either real strong-or absent.

[greg_atlanta]

It's probably the hoses in the engine (under plenum). Have they been replaced in the last 3-4 years?

Make a habit of turning off the vent/AC when you turn off the car. If you start the car and don't notice the smell *until* you turn on the vent/AC, you know it's from the engine.

[Fenvy]

yeah, check the o ring by your fuel pump, it's made with rubber and will deform after 10 years

[elwesso]

Theres a fuel hose in the rear that is VERY hard to see and its right over the block (and transmission) so if it drips it will REEK and not leave any visible evidence.....

Also, its right near the air intake for the HVAC so that makes it much worse...

[redmanfx]

Gas lines have vapor locks and should be blown out every once and a blue moon. I had a strong gas smell when I bought my Q and after checking all the lines I blew out all the vapor seals(locks or whatever you call them) and everything is ok now.

red

[SFBayQ45]

In response to earlier inputs/suggestion:

fuel pump and controller were replaced by the dealer last year...I was told that a new O-ring came with the fuel pump

turning the A/C ON actually reduces the smell somewhat....I'm guessing it masks the smell rather than reduces it, but I'm not sure

smell is strongest in the rear seats...as window is rolled down, the air circulates and pushes the smell up to the front, but regardless the back passenger suffocates from the smell more than front passengers...don't think the problem is from the engine or near the HVAC...it seems to be originating from the rear.

redmanfx - what's the procedure to "blow out" the vapor locks in the gas line. Is this something that only the professional can do?

[elwesso]

You might just take out the cladding in the trunk and make sure everything passes a visual check...

[SFBayQ45]

I wanted to revisit this issue to see if anyone has any further suggestions. Am I doomed to drive this car with ON/OFF fuel smell forever???

[reliant]

Had same issue, it was the rubber fuel lines lines top rear engine. Replaced all smell gone.

[PalmerWMD]

Are your plenum fuel lines original?

Fred..

[Q451990]

Check under the car in the back. The metal tubes from the gas tank go to some rubber hoses that connect to other metal tubes that run the length of the car. I would also suspect the seal between the filler tube and gas tank. I'd take the cladding out of the trunk and leave it out until you find this problem. When you smell the fuel, get out and check the trunk around both fuel tubes on the pump sending assembly, the o-ring area, the filler tube, etc... It sounds to me like maybe the purge canister isn't opening at times and maybe there's an excessive pressure build-up in the tank... just a guess, but you might also check the canister purge solenoid under the hood for corrossion on the terminals. It's the same solenoid as the one for the EGR, and I've found corrosion there before.

Good luck!

Heath