Help figure out a fuel leak (pic)

[BigD]

Hey guys. So my car has a fuel leak. It's on the passenger side, behind the wheel, and ONLY when the tank is full or almost full. It is exacerbated by driving really hard and turning left (I got shit at the last autocross cause when I spun out going left, when they went to pick up the cone I smoked, they saw fuel and it reeked.

I pulled the pump cover and everything there is minty, with no odor - even though when it starts leaking, I can smell it inside - when it leaks hard the stink is pretty hard inside too.

I removed the plastic well cover and went to fill it up and do some lefthand circles. I stupidly drove through a small puddle so it threw me off. The overflow tank was a bit wet and the bottom of the fender in the back but I wiped it off with a tissue and there was no smell. There WAS a gas smell from inside the wheel well. The tank itself is dry. I wiped every wet spot in the area with a fresh tissue each, and smelled. This spot is all gas, no other. What the hell is it? It looks like a dirt covered cover for a bunch of cables or hoses leading up to the overflow tank. I tried looking on the realoem diagram but I don't really get what I'm looking at, it almost seems like they go inside the body, but it could be that I have so much dirt there that it just seems that way. My car is an 09/86 so it shouldn't have the carbon filter. Anyway, here's the pic and a realoem diagram for reference:

[trent]

I bet part 19 in this diagram.

[trent]

The expantion tank stuff doesnt really have gas, just fumes.

[Mike325]

I was thinking the sme thing Trent was.

Is your tank wet itself? The tank, not the overflow.

[BigD]

Doesn't that hose end around the axle, or even infront of it? Or is it behind that cover that is soaked in gas (the pic is from behind the wheel).

No, the tank itself is dry, the leak is behind the wheel, not infront of it.

Thanks guys!

[Mike325]

That hose is right infront of the rear subframe. It goes over the TA.

[BigD]

That hose is right infront of the rear subframe. It goes over the TA.

Yeah but it goes in closer to the center of the chassis. Unless I'm wrong, my leak is right inside the wheel well somewhere. Like I said the darkness around that nut in the pic is gasoline. I gotta try to reproduce the leak strongly so there is no doubt where it's leaking. So far I'm still not 100% - but that dark spot around that nut is gas and that's around where I remember the leak coming from.

[Mike325]

So for clarification, the pic is of the right rear wheel well, with the wheel well cover removed?

[BigD]

So for clarification, the pic is of the right rear wheel well, with the wheel well cover removed?

Yup, the overflow/expansion tank is in the upper left corner in the shadow in the pic.

[Dave]

I can tell you this - I had a bad o-ring on the fuel pump on my 90 325i. Leaked from the same spot, and only when the tank was full. When I swapped the o-ring, there was no real accumulation of gas around the top of the tank - as it was nearing empty. When you pulled hte fuel pump cover, how much gas was in it?

For me, that fixed the problem.

[Jean]

I've replaced #19 hose before and if I am looking at the picture correctly your leak is nowhere near it... here is the picture of the hose

http://www.realoem.com/bmw/showparts.do?model=1074&mospid=47302&btnr=16_0107&hg=16&fg=10

Maybe pictures will help others pin point it for you

[BigD]

JEAN! AWESOME PICS, THANK YOU!!!

The fuel soaked spot in the pic is right here:



I'll remove the plastic cover and try to get it to leak again, that should tell the tale for sure. I have a feeling it's the braided #5 hose:



I had that accumulator thingimabob leak too, and I bypassed it with a normal fuel hose. What's the big deal about that hose, why does Real OEM show it as being 43 bucks? Do I have to get the one from the dealer or can I just get a normal fuel hose to replace it with?

Also, is this hose somewhat easy to replace? IE, can I replace it without dropping the tank, or not? If not maybe I should just cut off the leaking length for now, and add a hardpipe fitting to connect a new length of hose in its place for now...

Anyway, thanks again dude, I'll do some more investigating this week.

[jefrolison]

Someone on another forum had a leak in same spot- the plastic tee a couple inches left from your circled area broke off. I dont see that part in RealOEM drawing or list. He went to a hardware store and bought a plastic tee. The clamps pictured are not reusable.
Jef Rolison

[BigD]

Someone on another forum had a leak in same spot- the plastic tee a couple inches left from your circled area broke off. I dont see that part in RealOEM drawing or list. He went to a hardware store and bought a plastic tee. The clamps pictured are not reusable.
Jef Rolison

Thanks Jef! I guess the trick now is to get it to bleed with all the covers off... without driving through water this time.

[ScottL]

Like others have suggested, there are only two places where the fuel could be exiting the tank and getting up into the wheel well during a left-hander: the top vent line or the filler neck. My money is on the vent line. (This is the hose that is wrapped in a braided sheath.)

Fuel rising up through the filler neck should spill into the overflow tank unless the cap is bad. Make sure the line coming out of the bottom of the overflow tank is OK.

I purchased a length of braided vent line from BMA - only place I could find it. They piece they sent was too short (can't specify the length when ordering) so I just spliced in part of the old one. It was a bitch to thread this hose and the two small plastic ones through the narrow tube that runs from the wheel well to the tank cavity. I did it with the tank removed - could be tough with the tank installed but if you're lucky the hose will pop out near the access panel under the rear seat.

Good luck!