Question: C6 Gas Fumes after fill up

[Luiparra]

Has anyone with a C6 had a problem with strong gasoline fumes coming out after a tank fill up?
My C6 coupe does it until is about 3/4 to 1/2 full, and then I fill her up again and the fumes come back when I park her in the garage.
It is very uncomfortable, I have to crack open the garage door to let the fumes out for ventilation in the garage take over. Luckily, I do have fans and a side access door which help with the air flow through my garage. I have checked the floor, and I don't see any gasoline leaks or puddles (poodles yes, I have two of them, miniature, but they don't smell like gas:L)
I was already told by another member not to overfill the tank and let the gas pump clicker do it for me, and I tried, but still smell fumes, although not as bad.
If anyone can shed some light on this problem, maybe I could get it fixed.
Thanks guys/gals

Luis

 

[the boss]

If you have access to a code reader, check if there is code about the evap system. These codes can take many drive cycles to put the check engine on depending the type of driving your are doing. A problem whit the evap system may not leak on the ground but may give you strong smell of fresh fuel (not exhaust fumes). Keep posting. Steph

 

[Luiparra]

Gas Fumes

If you have access to a code reader, check if there is code about the evap system. These codes can take many drive cycles to put the check engine on depending the type of driving your are doing. A problem whit the evap system may not leak on the ground but may give you strong smell of fresh fuel (not exhaust fumes). Keep posting. Steph

Thank you Boss. I don't have access to a code reader other than my local Chevy Dealer which may charge me for finding out. I wonder if these gadgets are avail in the local Auto Parts stores at a reasonable price or for free if you buy the parts from them. I do not have an "check engine" light on either, everything works fine, including gas mileage, power/performance, etc. Just the strong smell of gasoline.hnoes

 

[the boss]

I don't live in USA but some forum members posted that many parts retailers offer to read the code for free for there customers. I think you should try this way to see if there are ''pending codes''. Pending codes may be present but because of ecm parameters they did not light up the check engine yet. Sometime, the kind of driving you do may take a long time to get the light on, EX: many short distances. There are solenoids on the evap system that may leak and let some fume go out when there are not suppose to, a small crack hose can do the same. Fuel dry pretty fast so if there is a small leak it may dry before making a wet spot under the car or on the floor. By the way, you can by a small code reader for a very affordable price. Small devise that hook to the diagnostic connector and link to a smart phone are also available and are not to expensive. On google you will find TSB (technical service bulletin) that may refer to this particular problem. The procedure I use at the shop is always the same, first visual inspection, second read codes, third read TSB, it save me a lot of time. If you finaly have to go to a shop, you may check forum vendors who may be close to your location. Keep posting

 

[the boss]

I type corvette gas smell on google and it took me to a lot of info whit the same problem. there is a lot of different things that cause this problem. Some fixed hoses on the canister, other replace fuel pump that where leaking but the fuel was staying on top of fuel tank and evaporate whit the heat of the exhaust so no leak but a strong smell, other had fuel tank problem that appear only when fuel level is half and over. Good luck

 

[Hib Halverson]

For an '08, the EVAP system codes are all either Type A or Type B DTCs. Type A codes turn on the service light after the first time the diagnostic fails. Type B codes, are pending after the first failure and turn the light on after the second failure. With Type A and B, the MIL goes off after the fourth time the diagnostic does not fail or if a scan tester clears the code. A history code remains for 40 cycles or until cleared with a scan tester.

If this odor of fuel has existed for more than two ignition cycles with cold starts and has existed when the fuel level is between 15 and 85% and the engine light has not come one, then it's unlikely the OBD has detected a problem with any of the monitored parts of the EVAP system. Nevertheless, if you can smell gas, there's a problem.

If the smell of gasoline is strong, even if you don't see liquid fuel leaking, that's a hazardous situation. I wouldn't worry too much about trying to find a code reader. I'd do a visual check for three possible problems.

1) A leak in the filler neck.
2) A leak in the cross pipe between the two tanks.
3) A leak in one of the tanks.
4) A blockage in the path gasoline take when it drains out of the filler cavity after fuel spills out of the neck during a fill-up.

 

[Luiparra]

For an '08, the EVAP system codes are all either Type A or Type B DTCs. Type A codes turn on the service light after the first time the diagnostic fails. Type B codes, are pending after the first failure and turn the light on after the second failure. With Type A and B, the MIL goes off after the fourth time the diagnostic does not fail or if a scan tester clears the code. A history code remains for 40 cycles or until cleared with a scan tester.

If this odor of fuel has existed for more than two ignition cycles with cold starts and has existed when the fuel level is between 15 and 85% and the engine light has not come one, then it's unlikely the OBD has detected a problem with any of the monitored parts of the EVAP system. Nevertheless, if you can smell gas, there's a problem.

If the smell of gasoline is strong, even if you don't see liquid fuel leaking, that's a hazardous situation. I wouldn't worry too much about trying to find a code reader. I'd do a visual check for three possible problems.

1) A leak in the filler neck.
2) A leak in the cross pipe between the two tanks.
3) A leak in one of the tanks.
4) A blockage in the path gasoline take when it drains out of the filler cavity after fuel spills out of the neck during a fill-up.

Hib,
Thank you for the analysis. I have noticed the smell is after I drive and put in the garage (after a ride). If the car spends a week without being started or run, I don't smell fumes. So it has to do after engine runs for a while. Next time I am at the dealer for an oil change, I will ask them to inspect for leaks or to scan with a code reader and see what we get. I am not too concerned about it now that I have isolated the issue to only after engine runs. As I said, fume smell clears up after a few hours. Thanks all for the hints and I will report back as to what the dealer results. I am still 80% on my oil, so it will be a while.

Luis

 

[Luiparra]

Tip for avoiding gas fumes.

In discussing this subject at a local classic car swap/meet/show in town, I was given a tip by another "Corvetter" who owns a 2005 - C6 Convertible. I have placed this "tip" in practice and it has stopped the gasoline smelling fumes in my garage after I fill her up and park it in. The trick has been to as soon as you shut the engine off and get out of the car, open the gas door, unscrew the gas cap and allow any pressure release from tank; screw the cap back on and close the gas door. This has worked!!!, I don't smell any more gas fumes even after I fill her up to the neck and park her in the enclosed garage. In any case, on my next oil change, I will have the dealer check the fuel vent system and gas emissions to make sure everythning is in its place and undamaged. I was also told that the factory warranty for emissions would still kick in after 5 years. This is a 2008 Corvette-Base Coupe with LS3 engine which I purchased last July 2012. In addition I also purchased an extended warranty for another 3 years or 100K miles, so it should be covered if anything is wrong, I hope!
Just wanted to provide this latest info and tip which is working. Thanks for all the readers, advisors and my fellow Vetters.

 

[Toms007]

Thank you, I may try this on my C5 as well.

 

[Luiparra]

GAS FUMES - Dealer Story and very surprised

Finally paid a visit to my local dealer to have my key fob re-programed after it shattered into pieces when I was walking in a Walmart Parking lot and it got tangled on my key chain. So after ordering a new one at $217.00 I asked the service advisor about my gas fumes in the garage after I fill her tanks up. The service advisor told me that I was not the first to complain about that issue and that there was no remedy other that what I was already doing: 1) opening the gas cap after I shut the engine down in the garage, let the pressure escape momentarily or 2) crack open the garage door and put the ceiling fans to run until the fumes are purged. (1) has helped and living in FL (2) can also help, so I got no problem with neither advice/action. They did ask me if I had a engine/check light on and "negative". So, I was really surprised they didn't want to sweetened me up on sometype of service, sensor or part replacement! uhhhmmmm???? I wonder why!

 

[froggy47]

Finally paid a visit to my local dealer to have my key fog re-programed after it shattered into pieces when I was walking in a Walmart Parking lot and it got tangled on my key chain. So after ordering a new one at $217.00 I asked the service advisor about my gas fumes in the garage after I fill her tanks up. The service advisor told me that I was not the first to complain about that issue and that there was no remedy other that what I was already doing: 1) opening the gas cap after I shut the engine down in the garage, let the pressure escape momentarily or 2) crack open the garage door and put the ceiling fans to run until the fumes are purged. (1) has helped and living in FL (2) can also help, so I got no problem with neither advice/action. They did ask me if I had a engine/check light on and "negative". So, I was really surprised they didn't want to sweetened me up on sometype of service, sensor or part replacement! uhhhmmmm???? I wonder why!

I am happy to give you the award for the dumbest comment from a service advisor this month. Seriously. I would not bring the car back there, ever. If it were me, I'd also contact GM customer service and relate the "advice" you got at that dealer.

The "service advisor" should be flipping burgers and not allowed to ever give anyone advice about their cars.

:ugh

 

[Luiparra]

Vette Burgers! Ha! Ha! (LOL)

I am happy to give you the award for the dumbest comment from a service advisor this month. Seriously. I would not bring the car back there, ever. If it were me, I'd also contact GM customer service and relate the "advice" you got at that dealer.

The "service advisor" should be flipping burgers and not allowed to ever give anyone advice about their cars.

:ugh

After thinking about it, I think UR right and I am going to follow your advice about talking to management. The dealer should at least tell me to bring it in to inspect for minor leaks at the filler neck or crossover tube, or fuel pump seal on the gas tank, but not live with it. That is OK advice by the guy I met at the swap meet and as a temp/band-aid until the root of the problem is uncovered. You are right! My Ford Truck has dual tanks and never have smelled fumes when I filler them up and drive in the garage! Why should a Vette do that?
This is the only dealer in a 40-50 mile radius and is very close to my home, so I made another appointment for next week to replace a speaker that is making a crackling noise, soooooo, I am going to surprise them with the news and my concern about the poor advice, Yes Sir. If after that, problem is not solved, I will take the next step in Regional Customer service. Thank you!!!

 

[Luiparra]

About th\e Gasoline FUMES - Diagnosis

So finally had the car looked at by the dealer after all the mongo-mango-jongo that they claimed "it is normal". They kept the car overnight and called me after two days. They found no traces of gasoline leakage anywhere by the fuel pump seal, tank, hoses, vents, fuel lines, filler neck, etc as gasoline leaves a residue/trace which attracts dirt and particles, everything appeared clean and dry
(I did topped off the tank before I took it in so they could spot any leakage while the tank was full).
The results were that these cars (we are talking C6) are equipped with a "computerized" fuel venting system that operates every 12 - 20 engine starts. When the system "vents", it is normal to smell the fumes until the process is done through the charcoal canister/can. This "venting" could take place at any given time upon computer demand and it could happen when the car is sitting in the garage (it would be nice to know when it is taking place so you can leave the car outside). If the system doesn't operate, then you would get an "check engine light" and the code would register for "fuel vent malfunction" (or something like that).

Is this a buyable diagnosis?:confused I would like to hear comments ! Thanks to you all!!!

 

[Toms007]

I suppose that could happen, but it sounds a little too convenient to me. If that WAS the case, why would you only notice this after you've filled the tank? Seems like if it was happening every "12-20 engine starts" that it would be doing it when the fuel level was down sometimes.

Kind of wish C4C5Specialist would check in here and put in what he knows about this subject.

 

[c4c5specialist]

HI there,

Lets be very clear, IN NO UNCERTAIN TERMS SHOULD YOU SMELL GAS UNLESS YOU ARE FUELING THE VEHICLE.

This is a safety concern and should not be passed off. Lets take a look at how the system works.

#1, it is a system by which if fuels your engine, AND RECOVERS VAPORS FROM EVAPORATION WITHOUT VENTING TO OUTSIDE AIR.

#2, when you are fueling, you may smell a bit but MOST of all vapors are forced INTO the charcoal evaporative canister as the fuel tank fills up.

This occurs because the excess vapors in the fuel tank are forced INTO the canister because the VENT solenoid is open at the other end. As fueling occurs, the fuel seals the filler neck, creating internal tank pressure. This excess pressure is forcing gas vapors into the canister where the vapor itself is absorbed by the charcoal internals, and only air is allowed to escape. All systems presently are engineered to do this.

#3, if you shut off your engine, and you smell fuel, there are 2 options here. You either have a fuel leak or a vapor leak. Due to the fact that you do NOT have a check engine light, I am thinking that there is FUEL leaking under your car OR on the engine. This leak on the engine will evaporate before hitting the ground.

So, the tests to perform in this case are actually very simple.

#1, you can pressurize the evaporative system with nitrogen, seal the vent and purge solenoids and see if the pressure drops.

#2, you can enable the fuel pump and pressurize the fuel supply systen and see if the pressure drops.

I do agree, if the dealership says it is normal, they are full of garbage. PER EPA guidelines, this is unacceptable, nevermind by GM service standards!!!!

Allthebest, Paul

 

[Toms007]

Thank you Paul for stepping in here and getting Luiparra on the right track.

 

[danjanuchowski]

i have same problem with my 2008 corvette

hi there, I recently purchased my first corvette last year and it is a 2008 base coupe, whenever I fill the gas tank up to full I always get overwhelmed by the gas fumes inside the car after it sits with the windows closed and it has a full tank of gas.... and it happens everytime I fill it up to full. once I get it down to a half tank of gas and let it sit... there are no fumes inside the cabin no more.. its only when I fill it up and then let it sit. I purchased an extended warranty last year and now I made an appointment to have this problem checked out.. I also have to get a new body control module installed since the dealership I went to last year messed it all up and now its locked and doesn't work at all... hopefully this time this dealership can figure out why my car fills up with the gas fumes whenever I fill it up.

 

[Chevy Customer Service]

hi there, I recently purchased my first corvette last year and it is a 2008 base coupe, whenever I fill the gas tank up to full I always get overwhelmed by the gas fumes inside the car after it sits with the windows closed and it has a full tank of gas.... and it happens everytime I fill it up to full. once I get it down to a half tank of gas and let it sit... there are no fumes inside the cabin no more.. its only when I fill it up and then let it sit. I purchased an extended warranty last year and now I made an appointment to have this problem checked out.. I also have to get a new body control module installed since the dealership I went to last year messed it all up and now its locked and doesn't work at all... hopefully this time this dealership can figure out why my car fills up with the gas fumes whenever I fill it up.

danjanuchowski,

Apologies to see you're experiencing fume concerns. I can understand any displeasure that this causes. Please keep us posted on your dealer visit and don't hesitate to reach out to us if our involvement is needed in communicating with the dealership.

Kind regards,

William R.
Chevrolet Customer Care

 

[danjanuchowski]

danjanuchowski,

Apologies to see you're experiencing fume concerns. I can understand any displeasure that this causes. Please keep us posted on your dealer visit and don't hesitate to reach out to us if our involvement is needed in communicating with the dealership.

Kind regards,

William R.
Chevrolet Customer Care

Thanks..I will post what the outcome is when I take it in next week thursday..they said it may take them a while to figure it out.

 

[danjanuchowski]

The other issue..

I am also taking my corvette into a different dealership because the one I took it to last year...West Herr Chevrolet of hamburg...messed up my body control module...I went there for them to program 2 new key fobs...and I waited for 6.5 hours for them to tell me that the system locked them out and they could not program the new fobs..they said I had to replace the body control module.. The system worked just fine before I took my car to them..I had everything programmed and now it is all erased and the system is locked. They told me to get a warranty plan and then get it replaced. I always wanted a corvette and I love the car but it's been a headache since I got it and the dealership messed it up even more. I can't wait to hopefully get the gas fume issue resolved and the body control module fixed.