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Mregor

Strong Gas Smell

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Mregor

Finally cleaned out the garage on Veterans day to make room for the vette. Put the car in the garage and at midnight, the wife wakes me up saying the hall smells like gas. I go out into the garage and sure enough, it smells like 20 gallons of gas has spilled onto the floor. I get a flashlight and look all around but can't see anything. Trace the smell to the filler neck. I bought the car when it was on empty. I filled it up and the pump kept shutting off. Probably 5 times while filling. I overfilled it a bit but none ran down outside of car, just into the drain. Not sure where that goes but that's what I figured it was. Pulled it out for the night. Could smell it faintly the next morning. Drove it to work and stopped and got a new gas cap. Figured that was it. Nope, still smells. I got under the car tonight and noticed driver side tank was damp on bottom. Pulled the shield and nothing really visible in that I couldn't see where it was leaking from. WIped it all down and put everything back. Stinks like crazy. Pulled it out again. Gas level is between 1/2 and 3/4. Car is 2009 Z06. Any suggestions where to start? I figured next is to pull the wheel well to see if I can see anything at the filler neck. I did a search and really nothing firm. Could be lots of things and none seem too easy. No CEL or service engine soon messages.

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Eddie44

Common problem on Corvettes. From what I've read though its been mainly on C5's. Maybe the C6's are finally getting to that age where they'll be next. I believe what you want to pay special attention to is the crossover tube.

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joe@cpr.com

If you recently have not had any work done in the area than this is an odd one. The crossover line does sound suspicious thas for sure. If you need to throw it on a lift let me know!

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TheCMSH

Maybe Rob (08Z51) will see this or send him a PM. Bitch of a problem to diagnose, fix, and get repaired under warranty. I believe his was the gasket on the top of a tank but don't quote me on that. It was a real deal, he even had me put my nose to it to confirm the issue. I sure wouldn't park it in the garage if I was you

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HOXXOH

NEVER try to top off the tank on a C6. As soon as the pump handle clicks the first time, it's as full as you can get. Of course, if it shuts off too early, it's because of the angle of the nozzle or because you are either pumping at max rate manually or on the high speed notch of the auto-fill. Place the nozzle straight and fairly deep in the filler neck and set the auto-fill on the low setting.

Now assuming you were filling too quickly and the shut off happened well before the tank was full and you didn't overfill, then you do have a leakage problem. I'd suggest siphoning out as much as you can. When you start the car again, any gas in the passenger side tank will go into the driver's side. Then don't fill any more than about 5 gallons when the low fuel light comes on. That'll keep all the gas in the left tank and none in the crossover tube. If you still have dampness, it's a left tank problem. If it dries up, then the problem is likely to be in the crossover tube or connections.

See this to get a visual of how it works. http://forums.corvetteforum.com/c6-tech-performance/2727302-how-to-replace-a-fuel-pump.html

Either way, if you continue to drive it, carry a fire extinguisher for safety.

Hopefully after you find the problem, it won't take too long for all the excess to evaporate and the smell to go away.

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P51tj

Gateway used some type of smoke on my Yeller C5 to find a tiny crack on top of the tank...it only let out fumes so there were never any drips or dampness. It can fill a garage in a hurry thats for sure!

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old yeller

NEVER try to top off the tank on a C-6

I agree with Tom. I went one click over one time and it seened like it was never going to stop running out of the tank. Interior smelled like gas but it went away quickly. It sounds like you have something else going on with your Vette.

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joe@cpr.com

We do have a smoke machine so we can throw that on it real fast if need be.

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Unreal

As Tom said, never top off or overfill a c6. There is a line from the top of the filler neck to the evap vent system. If you overfill gas spills into there. That can damage the fuel system, and fill the charcoal canister with fuel.

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Mregor

As Tom said, never top off or overfill a c6. There is a line from the top of the filler neck to the evap vent system. If you overfill gas spills into there. That can damage the fuel system, and fill the charcoal canister with fuel.

This is the first thing I'm goign to look at, but I'm not sure how the system works. It did overfill and about 1-2 oz went through (jsut a guess, a small amount but not enough to spill down the side of the car). Like I said, I didn't notice a smell when I picked up the car but it was on empty. Nor did I notice a smell when I first saw it or test drove it. I don't know how much gas was in it then. So, since I overfilled it, remember, the pump shut off several times while filling and it only took about 14 gallons on the fill from the low fuel warning, this is going to be the first place to start. Where is the evap canister at and how do you get to it? I would think that 5 dyas would be enough time for the little that was in there to evaporate but still this is the place I think I should start.

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Unreal

Evap is mounted to frame in passenger side wheel well. There is a little access port to get to the lines. You can't remove it without dropping the tank though. I would check the driver side first to make sure the fill neck looks good and the vent line is plugged in and working correctly. Another thing to check is the evap line/solenoid under the car by the mufflers. If it is stuck open/etc it could just be venting the tanks all the time.

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Mregor

Another thing to check is the evap line/solenoid under the car by the mufflers. If it is stuck open/etc it could just be venting the tanks all the time.Ho

This seems like a definite thing to check. how do I check it? Have no idea where it is. I found the part on a diagram on the evap system on Parts Taxi but it does not have any location reference. WOuldn't a bad purge valve throw a code?

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Unreal

It is on the inside of the frame rail right by the exhaust pipe. Next to the transmission. Passenger side.

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Mregor

Ok, thanks. But if the solenoid was stuck open, wouldn't it throw a code? I have no CEL.

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Unreal

It should. but sometimes the codes take a few drive cycles. It may pop a code if you keep driving it.

  • Upvote 1

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old yeller

Did you ever find the problem with this????

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C4orce2

This may not be helpful to you at all, but I often get a "strong gas smell" whenever I'm following Badbob. But I don't think its his car that I smell, may be Badbob himself!! :facepalm:

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Mregor

Now for the rest of the story...

Once I got below half tank, smell is gone. Not sure if it's just because the overflow finally evaporated out of the canister or if it is related to the half tank. It's my understanding that when you get to half tank it will use the driver tank only. This would imply that if I had a problem, it would be with the passenger tank. The passenger tank was completely dry when I crawled under. And to add more questions, look over the paperwork and it had the driver side tank sending unit replaced under warranty. So, it doesn't smell now. Think I'll just not overfill and hope that was the only problem. No check engine light so hopefully that's what it was.

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theChad

My '04 C5 did the same thing. It was the connection at the crossover tube to the drivers side tank. 1/2 full or less, no vapor. More than 1/2, stinky! I'd almost bet you have a crossover tube issue too.

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Mregor

My '04 C5 did the same thing. It was the connection at the crossover tube to the drivers side tank. 1/2 full or less, no vapor. More than 1/2, stinky! I'd almost bet you have a crossover tube issue too.

Thanks for the input. That could very well be since the tank was dropped to replace sending unit. Do you think that can be checked without dropping the tank?

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theChad

Not sure, I think the dealer pressurized it with smoke and found a crack at the tube/tank mating port. That would probably be the ideal test.

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HOXXOH

Now for the rest of the story...

Once I got below half tank, smell is gone. Not sure if it's just because the overflow finally evaporated out of the canister or if it is related to the half tank. It's my understanding that when you get to half tank it will use the driver tank only. This would imply that if I had a problem, it would be with the passenger tank. The passenger tank was completely dry when I crawled under. And to add more questions, look over the paperwork and it had the driver side tank sending unit replaced under warranty. So, it doesn't smell now. Think I'll just not overfill and hope that was the only problem. No check engine light so hopefully that's what it was.

Try waiting until the DIC reads "LOW FUEL" and then only put in 5 gallons for the next couple times. That will assure that no fuel goes in the passenger side tank. Assuming you have no fuel smell up to that point, then put in 8 gallons on the next DIC low reading. If you do have a fuel smell then, it's most likely the crossover tube or connectors and you'll only have to deal with it for a couple of gallons until that tank is empty. If you have no fuel smell after adding the 8 gallons, then you might as well fill it all the way, because you probably don't have a problem other than simply overfilling the first time. Just remember to only fill the tank on the slow feed rate and never add any after it shuts itself off.

One other warning. Either use Chevron gas or add a bottle of Techron every 3rd tank. The sending units are very sensitive to fuel that doesn't include Techron. That's most likely the reason the one on your car has been replaced.

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Unreal

The dealer I get parts with suggest replacing the orings about every time they go in to service a tank. I would bet the seal on the tank isn't 100% just like to said so a little gas is seep out of the crossover when it is full.

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Mregor

Try waiting until the DIC reads "LOW FUEL" and then only put in 5 gallons for the next couple times. That will assure that no fuel goes in the passenger side tank. Assuming you have no fuel smell up to that point, then put in 8 gallons on the next DIC low reading. If you do have a fuel smell then, it's most likely the crossover tube or connectors and you'll only have to deal with it for a couple of gallons until that tank is empty. If you have no fuel smell after adding the 8 gallons, then you might as well fill it all the way, because you probably don't have a problem other than simply overfilling the first time. Just remember to only fill the tank on the slow feed rate and never add any after it shuts itself off.

One other warning. Either use Chevron gas or add a bottle of Techron every 3rd tank. The sending units are very sensitive to fuel that doesn't include Techron. That's most likely the reason the one on your car has been replaced.

I will go this route. Hopefully the smell never comes back.

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