Raw Fuel Smell, only when full tank

[blocke]

So the past few weeks I have noticed that after filling up my car, I am smelling gas from inside the car while driving. I park in my garage, and the garage smells like gas too. The smell only sticks around until Ive driven and used 1/8th of the tank or so, then goes away completely until the next fill up.

I have checked under the hood, and there are NO leaks. Injectors, rail, lines, etc. No visible leaks under the car, or at the fuel filter connections.

I'm wondering if its something EVAP related? Having to do with the pressure when the tank is full? It seems to me that its fuel vapor leaking, not liquid.

I searched around, but no good leads. Thoughts? Anyone run into this issue?

edit More searching I came across this: http://forums.vwvortex.com/showthread.php?3983107

Would I have a CEL if this were bad, or is it a code that must be pulled via VAGCOM?

[R&Cs4]

Not to be overly obvious here, but are you sure you aren't dripping gas on your shoes/pants/hands?

[auxnbus]

Are you topping-off/overfilling? If you over fill the tank, there is a little drain around the fuel door that will drip the excess fuel into your wheel well area.

[blocke]

No and No. I did read a few threads about topping off, but I don't typically force any more in after the pump "clicks". Also wouldn't understand how that would cause the smell to be present IN the car for a few days, then completely go away.

[auxnbus]

Also wouldn't understand how that would cause the smell to be present IN the car for a few days, then completely go away.

Not sure - maybe a little fuel pools up somewhere and eventually evaporates. Again, just a guess.

[blocke]

Not sure - maybe a little fuel pools up somewhere and eventually evaporates. Again, just a guess.

Much appreciated. My money is some sort of vapor leak. Still researching the EVAP system and the check valves...
Its just somewhat scary, smelling strong fuel while driving, with the windows cracked.

[vacsimile]

Possibly the fuel pump and/or transfer pump seals under the back seat. Under the bench seat there are two covers bolted down with three philip's screws. Take those out to access the top part of the tank.

Inspect for leaks immediately after filling... Gasoline evaporates pretty quick, especially when air is moving across it.

[Ken_C]

@blocke did you ever root cause this one? Having the same issue.

[blocke]

@blocke did you ever root cause this one? Having the same issue.

I haven't had time to investigate it yet, but it is definitely still occurring. So far, I think the most likely culprit is what Vacsimile mentioned. I plan on checking mine out today or tomorrow. I'll report back.

[blocke]

Update: I was able to pull my rear seat and unscrew both covers for the pumps. The driver side definitely smelled like fuel. Not sure if this one is the main or transfer pump. The passenger side had no smell at all.
I ordered part # 1J0919133B to replace the gasket. Won't know for sure if this was the root cause till I replace it, but at this point seems likely.

[IslandHydro]

One possibility: Many cars (not sure about the S4) have a flexible piece of rubber tubing that connects the fuel tank to the gas cap fixture. These can dry out and crack, leading to the symptoms you describe.

[FWP!]

Update: I was able to pull my rear seat and unscrew both covers for the pumps. The driver side definitely smelled like fuel. Not sure if this one is the main or transfer pump. The passenger side had no smell at all.
I ordered part # 1J0919133B to replace the gasket. Won't know for sure if this was the root cause till I replace it, but at this point seems likely.

My girlfriend's avant has a leaking gas tank. We've known about it, and after getting under the car, I can see that someone has taken the tank down in the past.

When she would fill the car up and bring it home, I can kneel down and look at the driver's side of the gas tank and see this big wide wet streak down the side of the tank. I'm guessing there is a crack on top that they tried repairing before, and the repair stopped working recently. I've looked into a used one, but Arizona law requires gas tanks get holes drilled in them at junk yards, and new ones are $1300 from Audi. I may take the tank down this winter and see if I can do a better patch, either some 2 part epoxy or I will try doing some plastic welding. In any case, it's gonna suck.

I did some google'ing a few months ago about this and it seems to be a not so unheard of issue, especially with avants. To me its a safety problem and I think Audi should fix it, sorta like how they'll replace the heated front seats if they ever over heat like I've read about.

[2004B6S4]

I have the same issue with the smell, only when the tank is full. When I first noticed the issue I was able to fill up every time without the pump stopping in between. then I started getting what I think is an evap problem and it gradually got worse and worse, to the point that now I can only pump about 3 gallons (sometimes more depending on the pump) before the pump triggers itself to shut off, even if my tank is almost empty. I'm not sure if the 2 issues are related or not but it seems likely. I haven't had a chance to try the evap canister fix that I read about in another thread but I plan to do that. in the mean time I just fill my tank to about 3/4s full to avoid the smell. and pump slowly

[blocke]

I have the same issue with the smell, only when the tank is full. When I first noticed the issue I was able to fill up every time without the pump stopping in between. then I started getting what I think is an evap problem and it gradually got worse and worse, to the point that now I can only pump a gallon or two before the pump triggers itself to shut off, even if my tank is almost empty. I'm not sure if the 2 issues are related or not but it seems likely. I haven't had a chance to try the evap canister fix that I read about in another thread but I plan to do that. in the mean time I just fill my tank to about 3/4s full to avoid the smell. and pump slowly

My car did exactly the same thing the last 2 times I filled up. It was the same gas station both times, so I just thought it was shitty pump. Through the whole time the smell has been there, I've only had problems pumping the last month.

[aroderick56]

I have the same issue with the smell, only when the tank is full. When I first noticed the issue I was able to fill up every time without the pump stopping in between. then I started getting what I think is an evap problem and it gradually got worse and worse, to the point that now I can only pump a gallon or two before the pump triggers itself to shut off, even if my tank is almost empty. I'm not sure if the 2 issues are related or not but it seems likely. I haven't had a chance to try the evap canister fix that I read about in another thread but I plan to do that. in the mean time I just fill my tank to about 3/4s full to avoid the smell. and pump slowly

The constant clicking off on the pump is your canister. It's clogged/saturated/full but it wont't let the system vent properly. You can test for it easily and only costs a for a few dollars.

This thread has some helpful info
http://www.audizine.com/forum/showth...Detection-pump

[blocke]

Thought I'd close the loop on this issue for anyone else experiencing this. I finally had to fill up again (I drive <300 miles a month). The fuel smell is no longer there, and the pump was not giving me grief when filling either.
So it seems that this was all attributed to a bad tank seal on the drivers side as detailed earlier in the thread.

[FWP!]

So I'm getting a raw fuel smell now in my RS4 when I fill up the tank. I took the two covers off under the rear seat and thought maybe the transfer pump seal was the culprit because it was a tiny bit wet there, so I replaced the gasket with a new one from JHM and the smell came back after filling up yesterday.

I don't see any gas on the exterior of the tank when I look under there, but I'm wondering where else I should check. Perhaps the fuel filler neck?

[FWP!]

Just to follow up, I found a crack in my sending unit's base, seen in this photo. The little, dark crack at the 12 o'clock position is what I'm referring to and I'm having to buy a whole new sending unit.




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[blocke]

Bummer. 6 months since I fixed this, filled up a few times and still no issues.

[ingolstadt-fan]

Just to follow up, I found a crack in my sending unit's base, seen in this photo. The little, dark crack at the 12 o'clock position is what I'm referring to and I'm having to buy a whole new sending unit.




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I found the exact crack in the same spot on my A4 B6. I'm trying JB Weld first. That should do it. Thanks for the confirm.

[Terry.Reese]

Mine had a crack as well, got an aftermarket one and have been on it for almost 2 years no issue. I also have a LDP replacement and will be changing out the charcoal container ina bit though, tired of the stopping every few seconds on fill up.

[WhatsATurbo]

I found the exact crack in the same spot on my A4 B6. I'm trying JB Weld first. That should do it. Thanks for the confirm.

I don't think that will work. That plastic is likely fluorinated to help with chemical resistance (gas) and also with evaporative containment (meaning it'll keep gas fumes in). JB Weld is neither of those and fluorinated plastic is difficult, if not impossible, for any adhesive to stick to. Obviously you can try but you should plan for a replacement part ASAP.

If it's any consolation I had to replace mine last year ('07 RS4) for the same problem.

Ryan

[Spazdoc]

Update: I was able to pull my rear seat and unscrew both covers for the pumps. The driver side definitely smelled like fuel. Not sure if this one is the main or transfer pump. The passenger side had no smell at all.
I ordered part # 1J0919133B to replace the gasket. Won't know for sure if this was the root cause till I replace it, but at this point seems likely.

I have been getting this since driving my '04 from Phoenix to Chicago last week. Can you drive the car with the covers off? Want to check when I fill the tank.

[VinnysS4]

I have been getting this since driving my '04 from Phoenix to Chicago last week. Can you drive the car with the covers off? Want to check when I fill the tank.

Yes you can. The pump/level sender sits on the passenger side and the second level sensor is on the driver side.

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[Spazdoc]

Just to follow up, I found a crack in my sending unit's base, seen in this photo. The little, dark crack at the 12 o'clock position is what I'm referring to and I'm having to buy a whole new sending unit.




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Well, I just pulled the cover and I found the same exact crack and a pool of gasoline. Gonna go drive around a little to lower the fueld level and hopefully stop the leak. Looks like I will be ordering a new one. I assume the whole sending unit needs to be replaced, not just the base?

[VinnysS4]

Well, I just pulled the cover and I found the same exact crack and a pool of gasoline. Gonna go drive around a little to lower the fueld level and hopefully stop the leak. Looks like I will be ordering a new one. I assume the whole sending unit needs to be replaced, not just the base?

If that's the drivers side, you need a new sending unit. If it's the passenger side, you need a new fuel pump. They are one assembly and I don't believe they sell just the top part. You could remove it and try to plastic weld it depending on what type of plastic it is.

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[AMCast]

Currently having this issue on my '12 a4. Garage smells like fuel after refilling. Checked under the fuel reservoir and I'm seeing a streak of gas leaking out and finding a spot on the garage floor that smells like gas. How can I see the top of the reservoir? To verify any cracks?

[d2a4]

Currently having this issue on my '12 a4. Garage smells like fuel after refilling. Checked under the fuel reservoir and I'm seeing a streak of gas leaking out and finding a spot on the garage floor that smells like gas. How can I see the top of the reservoir? To verify any cracks?

Pull the seat bottom out and unscrew big cap to see it, cracked is hard to find sometimes, I could not spot mine when I took it off, but after replace it no more smell.

[AMCast]

Pull the seat bottom out and unscrew big cap to see it, cracked is hard to find sometimes, I could not spot mine when I took it off, but after replace it no more smell.

The fuel pump cap? And what did you replace? The whole reservoir?

[d2a4]

The fuel pump cap? And what did you replace? The whole reservoir?

I replaced the whole fuel sensor assembly

[TSoich]

Looks like I have a similar crack resu;ting in the after fillup fuel smell / leak... will set up the gopro to be sure taht is where the leak really is next time I fill up.

If so, need to decide betweem spemding $100 for the VDO (OEM) part or $400 for the genuine Audi... amyone have any experience?

Thanks

[VinnysS4]

If so, need to decide betweem spemding $100 for the VDO (OEM) part or $400 for the genuine Audi... amyone have any experience?

Thanks

Its the same part made by the same people who made the original pump. Dont see a downside tbh. I've ran vdo pumps and never had an issue

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