Fuel smell inside gas door?

[Jeffs Black 97 Formula A4]

I never really noticed this before (most likely because I rarely spend time in that area). Recently, I was waxing the rear quarter (with the fuel door open) and noticed a slight vapor (almost like stale gas or charcoal). I know the charcoal canister is right next to it (it has a slight buzzing sound when the car is running).

I still hear a "whoosh" sound when opening the gas cap allowing the vapors to escape. I just installed a new cap too thinking that might be the reason for the smell. I don't smell the vapors when the car is running, and I don't smell gas inside the car at all. I only smell the vapor inside the fuel door a few minutes after I shut off the car.

The car still runs great and has no SES light at this time (this is after 4-5 trips after noticing the smell which might've been there the whole time, just never noticed it before).

Sorry for the long post, just trying to figure out if this is common, or if I really have a problem. Thanks!

EDIT -- I did take off the plastic cover just above the rear tire and was able to locate the canister. All the hoses looked fine.

[Rob B (shoebox)]

Your canister might be saturated.

A whoosh sound is fairly normal when opening the gas cap.

[Jeffs Black 97 Formula A4]

Your canister might be saturated.

A whoosh sound is fairly normal when opening the gas cap.

Yep, I know the whoosh sound from opening the gas cap is normal (I stated that figuring I can rule that out).

Is there anything I can do if the canister is saturated?

[Rob B (shoebox)]

Yep, I know the whoosh sound from opening the gas cap is normal (I stated that figuring I can rule that out).

Is there anything I can do if the canister is saturated?

Other than replace it, I don't know.

[Jeffs Black 97 Formula A4]

Revisiting this one.

Is it possible the temperature changes are causing me to smell fuel vapors when sniffing inside the gas door (30 degrees outside, with a warm car)?

[Bananasaboutcars]

You might be smelling it after you shut the car off, because when the engine is running the gas tank is under pressure, and the canister is under vacuum from the engine. The vapors are supposed to get sucked out of the gas tank through the canister and into the engine, when the sucking stops (i.e., shut down), the vapors leave through small holes in a loose hose or crack in the canister because the gas tank is still under pressure. As the pressure in the tank is relieved over time the smell should go away...until the next time you stop your engine.

Make sure the hoses look good from the inside, not just the outside. and make sure they fit tight. vacuum hoses are cheap to replace, and they wear out every 5-8 years or so. and no open flames or cigarettes lol.



www.bananasaboutcars.com

[Jeffs Black 97 Formula A4]

I replaced the gas cap (twice because the first replacement was apparently defective). I actually smelled even more vapors after replacing with the first replacement cap. Now that I have the second replacement cap, the smell has been greatly reduced to almost nothing when I turn the car off.

I still smell a very little bit of vapor, but it seems I have to be really sniffing hard for it now.

EDIT -- If I replace the vacuum hose, does this mean I have to run it from all the way underneath the car into the engine compartment?

[Injuneer]

Problem with this analysis is that the EVAP solenoid is not open all the time, and typically not at idle. It only operates under conditions that the PCM feels the engine can handle the flow from the canister. You can watch for EVAP purge solenoid on a scanner. I've looked at data logs from hundreds of cars, and the EVAP purge is an intermittent process. The solenoid is actually pulsed to modulate flow and the PCM reports the duty cycle of the solenoid.

The system is not always under vacuum. The heat from the pump is enough to create a positive vapor pressure. The pressure vents through the canister. If the canister is saturated, it can't absorb the hydrocarbon vapors from the tank venting, and you will smell them at the back of the car. If you overfill the tank frequently, you can have liquid getting into the canister. If your system is not working correctly (cracked vacuum hoses as noted above, solenoid or hoses plugged with carbon, solenoid not opening) you aren't removing any collected hydrocarbons from the canister, and eventually is saturates and everything starts to smell.

Test a vacuum line with a small hand held vacuum pump, before replacing it. The main line to the front of the car is a hard plastic, and generally doesn't leak, but the hoses at the tank are rubber, and they rot and crack. Those are the hardest ones to access, since they are sandwiched tight between the tank and the body.