raw fuel smell!!

[kismetcapitan]

eek, on the commute home, I smelled the unmistakable smell of raw fuel coming in through the vents. It was cold and rainy, so I was using the heater for the first time in awhile.

what's the fuel pressure in the fuel lines? do pinhole leaks develop, or to rephrase that, has anyone experienced that? It's a cheap fix, if the lines are accessible, but man is it a pain in the ass, not to mention a fire hazard!

I've spent thousands in a total overkill fuel system in my Skyline, and when people ask why, I just tell them of the month where the car sprung five fuel leaks...the only OEM fuel part left on that car are the injector O-rings. Yes, I was frustrated and threw out the entire system!

Hopefully, this isn't as big a problem...

[MaxRS6]

^ Is it when you fill up the tank? If the smell goes away when it is under about 3/4 of tank- then you probably have the infamous leak at the fuel tank nipples.

http://www.rs6.com/showthread.php/22747-Gas-tank-leaking.?highlight=gas+tank

[kismetcapitan]

well, I didn't smell it again; I'm at 7/8th on the fuel gauge. I think I'll talk with the dealership and see if they'll replace the tank under the recall. And I guess while they're at it dropping the rear subframe, they can set up the rear suspension properly when they reassemble everything!

[kismetcapitan]

Well, I've localized the smell and it's not encouraging...it's behind the engine on the passenger side. So I'm guessing it's definitely fuel system related...fuel pressure regulator? Or some fuel hose connection?

Even more disheartening...I think I found a leak from the cylinder head gasket, passenger-side cylinder bank, coming out from near the firewall end of the head.

What's the damage going to be for these repairs?

[kismetcapitan]

my bad, it's the valve cover gasket. <$100 for the gaskets, how bad's the labor?

[MaxRS6]

If it is the passenger side valve gasket- PIA. Bummer to tell you that Audi says the engine needs to be pulled. This is one of those items I always have done when my engine is out as I just did when they replaced my turbos.

[Jimmy]

Shouldn't it smell like oil if that valve cover gasket is leaking?

Do you really have to pull the engine? ...or just lift it up some to get access to it?

[kismetcapitan]

well, ten days of daily driving, and no gas smell at all. Weird.

I cleaned the engine, and I can see where the gasket is leaking. Slowly. In a week, oil residue has crept a whopping 1/8" at one spot. So I'll have to do the gaskets, and just watch that point until my next major service.

[kismetcapitan]

jeebus, it's like my car's time of the month. same strong smell of raw fuel, same location - behind the passenger-side airbox.

Is that where the fuel pressure regulator is? Should be a cheap fix if it starts happening more frequently.

Any other thoughts on what it could be? Like, where does the fuel tank ultimately vent to (after passing through charcoal filters, etc)? It could be the fuel tank vent system saturating, then spilling over...? just a shot in the dark...?

[marklar182]

For the leaky valve cover, snug the bolts down a little and see if that stops the seepage.

[JSRS6]

Fpr is under the passenger side of the box, inboard rear of the passenger fuel rail.

[kismetcapitan]

For the leaky valve cover, snug the bolts down a little and see if that stops the seepage.

that should hopefully take care of that; the valve cover gaskets were done less than 10K miles ago.

still baffled by the fuel leakage. Not a whiff today. It's like it builds up and then bursts out? Not loads, but enough to smell up the engine bay as it vaporizes.

if my nose is pointing in the right direction of the problem, then it is the FPR, or something connected to it.

[JSRS6]

Pull the airbox, pull the fpr, and check the upper and lower o-rings. Might just be debris, try cleaning them off, as well as the area they seal to.

[4everRS]

That area is also where the fuel line comes into the engine bay. You might try to snug it down a bit.

[kismetcapitan]

sounds good, thanks!

[kismetcapitan]

well, the smell is stronger and happening more often. guess it's time to pull the airbox and sort this one out.

[kismetcapitan]

tried something else on a whim. I undid the gas cap, and was hit with a massive blast of fumes. Since then, no fuel smell, and no blast of fumes when undoing the fuel cap either. although the source is very clearly from behind the engine around the fuel pressure regulator area (and I did finally google an A6 owner that had the same issue that was NOT the fuel tank - I've had the recall done).

The fuel smell has always happened when I drove a short distance, then parked for a couple hours. Otherwise, it doesn't happen, and it's hard to replicate for the local indy garage.

[Cochese]

tried something else on a whim. I undid the gas cap, and was hit with a massive blast of fumes. Since then, no fuel smell, and no blast of fumes when undoing the fuel cap either. although the source is very clearly from behind the engine around the fuel pressure regulator area (and I did finally google an A6 owner that had the same issue that was NOT the fuel tank - I've had the recall done).

The fuel smell has always happened when I drove a short distance, then parked for a couple hours. Otherwise, it doesn't happen, and it's hard to replicate for the local indy garage.

Did you ever resolve this?

Just experienced the strong raw fuel smell. Had the tank valve recall done a few months ago. 123,XXX miles with stock fueling. I had the car idling for about an hour in traffic and noticed it for the first time when I got out of the jam. It was super hot out. The dash showed 113F.

I pulled the gas cap and it had built up a s-load of pressure. I'll monitor it for the next day and take it in to the dealer if it continues. I can't get under the hood at the moment since the damn hood release pull is stuck behind the damn grill. I need to figure out how to get that thing out.

[1uglymug]

I can't get under the hood at the moment since the damn hood release pull is stuck behind the damn grill. I need to figure out how to get that thing out.

Mine did this when I first bought the car. To get the hood release unstuck, you need a thin arm. Pop the hood from inside the car. Then reach up underneath the hood itself and pull the level straight forward and somewhat downward. It will eventually pop open if its advanced far enough. This is much easier than trying to feed it back through the hole from this position.

If you need a picture of the inside to get an idea of what you are tugging on, I can upload a picture. Keep me posted.

[Cochese]

Mine did this when I first bought the car. To get the hood release unstuck, you need a thin arm. Pop the hood from inside the car. Then reach up underneath the hood itself and pull the level straight forward and somewhat downward. It will eventually pop open if its advanced far enough. This is much easier than trying to feed it back through the hole from this position.

If you need a picture of the inside to get an idea of what you are tugging on, I can upload a picture. Keep me posted.

I'm 603/235 so I'll need to recruit someone with little pickpocket hands.

Thanks for the picture upload offer. I will indeed keep you posted!

[Chung]

I used a skewer for a while. Once you develop the technique it is not so bad... I did fix the latch eventually though.

[kismetcapitan]

I have a length of coat hanger wire bent in a certain shape to fish that thing out if it moves out of alignment.

But my final fix was to add a bit of epoxy putty to where the latch arms rest on the steel U thing. This props it up a bit and prevents it from retracting far enough to pop out of place. So far, so good!

And while my car had every little thing fixed...I guess that only counts for summer. When car camping at Indianapolis Motor Speedway last week, it went into the 50s at night. And when I started up the car - raw fuel odor for 5 minutes, just like last year. It is definitely linked to being cold, and being parked outside (it won't do it when I start off from home since I park in a fairly warm fully enclosed garage year-round). So I guess this is the final gremlin I need to hunt down.

[ben916]

I have a length of coat hanger wire bent in a certain shape to fish that thing out if it moves out of alignment.

But my final fix was to add a bit of epoxy putty to where the latch arms rest on the steel U thing. This props it up a bit and prevents it from retracting far enough to pop out of place. So far, so good!

And while my car had every little thing fixed...I guess that only counts for summer. When car camping at Indianapolis Motor Speedway last week, it went into the 50s at night. And when I started up the car - raw fuel odor for 5 minutes, just like last year. It is definitely linked to being cold, and being parked outside (it won't do it when I start off from home since I park in a fairly warm fully enclosed garage year-round). So I guess this is the final gremlin I need to hunt down.

Does this happen when the car is warmed up?

[kismetcapitan]

Does this happen when the car is warmed up?

nope, if the engine bay is warm, no smell. so whatever is leaking is temperature sensitive.

[ben916]

hmmm, I wonder if it is the same issue that V8Weight had with his injectors?!?!
There is a plastic ring on the injector and it was cracked.
He stated that he smelled fuel but couldn't trace where it was coming from... eventually found it...
There is a photo of the offending injector...

er, well not the same....
http://www.rs6.com/showthread.php/21661-Leaking-injector-O-rings?highlight=injector

[kismetcapitan]

thanks Ben, that could very well be it - it's coming from a specific location, which if it were an injector O-ring, would be the rearmost cylinder on the left side of the engine bay. No codes, no performance issues, but a worn O-ring could leak a bit when cold, but expand and seal properly when warm.

That was what took down the space shuttle Challenger; thankfully this O-ring is in a far less critical location!!

[Tom Sawyer]

This brings back memories of my B5 S4 after I did an GIAC chip, had leaks around a few injectors. Almost turned into a car-b-que situation so definitely worth seeing if that's it. I'm not sure how much fuel pressure is increased with the RS 6 tunes, but I'm guessing it is to some degree.

[lswing]

With stock fueling I logged my injectors working around 73% max. Went up to 110% of the stock fueling and injectors were working about 77%. More fuel, but not sure if there's really any pressure change. Fingers crossed on the tank valve myself, yet to have it looked at...

[marklar182]

Of course the fuel pressure changes when boost is turned up. The FPR is a rising rate type, so more boost = more fuel pressure.

[kismetcapitan]

as a rule of thumb, fuel pressure rises 1:1 with boost pressure. Injector duty (given as a percentage) basically says how long the injector stays open, and has nothing to do with fuel pressure.

Fuel lines in my experience can generally take whatever pressure you throw at it (unless they're truly cheap/crap). Where high fuel pressures are a worry are with fuel pumps - if they can keep up with higher fueling demands, and some pumps hit a wall - they might be able to deliver a certain pressure, but flow is way down, which will cause a massive drop in fuel pressure as soon as your injectors open up to a high duty cycle (like 70%).