Gas Odor After Fillup

[Stram]

I have searched the forums and cannot find any results. But, whenever I fill up my car (2002 e39 M5) it smells of gas and it's strongest from the rear passenger door/trunk area. I cannot find a leak or pinpoint where the exact location of the smell is coming from, but within about 15 minuet the whole interior of the car smells of gas. I suspect it's being overfilled, but after filling up today the car still smelled of gas even-though the gage didn't say the tank was full. Any advice would be greatly appreciated. Thanks

[larrym3711]

Search the forum on this topic for good info. Generally there is a problem with the gas recirculation hardware or hoses at the top of the tank.

larrym3711
2001 540iA Sport

[Jarhed]

Fuel level sensor, right and/or left. I'm dealing with the same issue now, except that my fuel level is always correct. Can't stand the smell.

[AK_5eries]

Don't overfill. Stop filling at the first click.

[edjack]

Pull the right rear fender liner. Go fill the tank. Inspect.

Next, do the same with the back seat bottom.

[Stram]

I decided to remove the rear seat bench and the smell of fuel got stronger, so I decided to unscrew the 3 screws surrounding the fuel pump and... Surprise! I have a new pet who is now renting out the rear of my car! All joking aside, it smelled strongly of fuel and I'm a little weary as it could be dangerous. I noticed that a blue tube looked a little bloated/deteriorated around where it meets the yellow cover, but there wasn't any signs of leakage. I was wondering where that tube goes and if I can access it to further inspect it? What I should do from here? ... And how did the mouse get in?



(Deteriorated tube shown above, I was wonder where it goes)



Is there a gap where the mice would be able to further nest? (I poorly attempted to demonstrate it above with the red lines)

[Ed CT]

There is a gas tank vent hose that runs from the filler tube (near the top), thru the fender well liner, and into that area above the fuel pump and below the access plate. The mouse could have chewed thru this vent hose (ask me how I know this!), since that is what they do to keep their teeth from growing too long. The hose connects to the fuel tank top, toward the front of the car, in front of the access hole opening, You'll need to look under there to inspect it.

Mice can climb up and onto the top of the fuel tank. The nice cozy fuel pump access cover makes a great foundation for a mice nest. I've since replaced the nesting material with D-con after R&Ring the vent hose. no mice issues since.

[MontanaRob]

try this
http://www.bimmerforums.com/forum/sh...5#post28127425

[Only1Balto]

Mine does this too. I always stop after the fist click.

[Stram]

Hello Everyone,

I decided to take another look and removed the back seat and plate covering the passenger side fuel pump. In the process I dropped a screw and was inches away from the yellow cover... And noticed the TINIEST hole on the cone shaped protrusion of the yellow cap, since then I have put a walking stick end cap (look it up on Google) over the protrusion and hole and no more smell! I am having trouble uploading a picture, but you can see it if you look closely at with the 1st picture I posted earlier.

[Jason5driver]

Bump...
Recently getting the smell of gas inside the cabin after fill up, and after the car is sitting for a bit.
It has not done this prior to having it sit for 2 weeks in the garage while we were out of town.

[Flounderasu]

Bump...
Recently getting the smell of gas inside the cabin after fill up, and after the car is sitting for a bit.
It has not done this prior to having it sit for 2 weeks in the garage while we were out of town.

Pull up the rear seat cushion.....I'm chasing a fuel smell outside the car and the first thing I checked was the area under the seats....everything was dusty and bone dry...so my leak is elsewhere.

[pleiades]

Have you had any reason to remove the passenger-side rear wheel liner lately?

http://www.realoem.com/bmw/enUS/show...diagId=16_0325

See part #22 (... I think ...). Sometimes that drain tube gets loose where it slips into the rubber gasket around the fill cap. It's meant to catch and drain any gas spill from topping up, but if it slips out of place, gas can get all over the upper/inner side of the wheel liner and stank....

[Flounderasu]

Have you had any reason to remove the passenger-side rear wheel liner lately?

http://www.realoem.com/bmw/enUS/show...diagId=16_0325

See part #22 (... I think ...). Sometimes that drain tube gets loose where it slips into the rubber gasket around the fill cap. It's meant to catch and drain any gas spill from topping up, but if it slips out of place, gas can get all over the upper/inner side of the wheel liner and stank....

Yeah I want to check all the lines - my issue of smell and wetness on the bottom of my tank occurs whether full or near empty however...

[Jason5driver]

Bump again.
Filled the car up and parked it in the garage over night, and fumes were so strong, we were scared to turn the light on for fear of blowing up the garage and car....

[Firstbmw528]

Mine was the level sending unit and if I filled up high enough it would actually leak on a hill as well. That's where I would start to find out if the smell etc. is on the drivers or passenger side and check for cracks in the plastic.

[sleuth255]

Or the rubber gasket that seals the sender (located under that yellow cap) has gone bad.

[flemsmith]

Have exactly this same problem. (2000 540i) After removing the bench cushion, its not yet clear to me how exactly to remove the bottom of the rear seat. Thought I'd do a little searching before I try and end up breaking something. I see the two heavy bolts holding the seat belt ends. Any tricks I need to know? After removing the rubber wiring covers, I had wet gas on top of both fuel level sensors after a full fillup. I've been running on 1/2 tanks for awhile. Appreciate any inputs. Roy

[DennisG01]

Have exactly this same problem. (2000 540i) After removing the bench cushion, its not yet clear to me how exactly to remove the bottom of the rear seat. Thought I'd do a little searching before I try and end up breaking something. I see the two heavy bolts holding the seat belt ends. Any tricks I need to know? After removing the rubber wiring covers, I had wet gas on top of both fuel level sensors after a full fillup. I've been running on 1/2 tanks for awhile. Appreciate any inputs. Roy

The bench cushion IS the bottom (what you sit on). The seatback is the vertical section. Or are you confusing these terms? Assuming yes... to remove the bench cushion, just pull up firmly on each corner. However, you also mentioned that you've also looked at the level senders, which means you've already removed the bench. So I'm confused at what you're talking about? Please clarify.

And, read above about the sender gasket.

[Ed CT]

Have exactly this same problem. (2000 540i) After removing the bench cushion, its not yet clear to me how exactly to remove the bottom of the rear seat. Thought I'd do a little searching before I try and end up breaking something. I see the two heavy bolts holding the seat belt ends. Any tricks I need to know? After removing the rubber wiring covers, I had wet gas on top of both fuel level sensors after a full fillup. I've been running on 1/2 tanks for awhile. Appreciate any inputs. Roy

Sounds like you've already removed the rear seat bottom cushion. This is all that needs to be removed for accessing the (2) fuel tank covers. The rear seat back cushion doesn't need removal for this. If you do need to remove it, there are (2) bolts at the bottom of the seat back cushion, and the top of the seat back (IIRC) is connected by hooking into the framework behind it. The other bolts holding the seat bet ends are just that - for the seat belts. No need to remove these unless you are taking out the seat belts, too.

[flemsmith]

To clarify, I was thinking I'd need to get to the whole top of the gas tank to see exactly what was leaking. I didn't really notice the serrated circles in the insulation that let you have access to the metal cover plate with its three phillips screws. For any other noobs who get this far and start searching, (and assuming you're the first to get this far in your car looking for a gas leak), just take a sharp knife and follow the circular outlines to pull back the insulated circle (about 8" in diameter) that lets you access the float level sender covers. The covers are threaded, and looks to me like use exactly the same 'wrench' adapter as the hexhead beemer R1200 series motorcycles. I have new rubber gaskets on order. If that fixes it, I'll be happy to put it all back together without going further. If not...!?!...at any rate, thanks for helping rather than pointing out how little I knew about what I needed to do. Roy

[flemsmith]

ff above post, I had my local indy replace the fuel flange cover gaskets. (No help, and the old ones looked fine, for what that's worth.) Immediately went to fill up the tank with the flange covers accessible, and there was an obvious leak coming directly thru the plastic flange on the fuel pump side. I'll either stop the leak with some Caswell motorcycle gas tank liner, or look into replacing both the plastic covers. Meanwhile, my fuel gauge is no longer working properly. After the fillup, it only reads half full. It's always worked perfectly, so something is now wrong with the level sensor(s). Looking for advice; I read somewhere that the resistance of both level senders need to 'match' in order for the gauge to work. Assume I can just pull the connectors and check the resistances...!? But not clear what corrective actions to take. Thanks in advance for any help. Roy

[Jason5driver]

ff above post, I had my local indy replace the fuel flange cover gaskets. (No help, and the old ones looked fine, for what that's worth.) Immediately went to fill up the tank with the flange covers accessible, and there was an obvious leak coming directly thru the plastic flange on the fuel pump side. I'll either stop the leak with some Caswell motorcycle gas tank liner, or look into replacing both the plastic covers. Meanwhile, my fuel gauge is no longer working properly. After the fillup, it only reads half full. It's always worked perfectly, so something is now wrong with the level sensor(s). Looking for advice; I read somewhere that the resistance of both level senders need to 'match' in order for the gauge to work. Assume I can just pull the connectors and check the resistances...!? But not clear what corrective actions to take. Thanks in advance for any help. Roy

Replace the fuel sending unit .

[flemsmith]

Ok, thanks. I may do that, but first I'm gonna see if I can fix the gas leaks with the Caswell epoxy. If that works, I might just yank the covers again and visually check the level floats. After all I'm fairly cheap if I can get away with doing something that actually works. If not, yeah, I'll replace one or both of the flanges, which so far I believe means I have to buy them with the level sensors attached. Roy

[DennisG01]

If the gasket you are referring to is the rubber one between the yellow piece and the tank, that meant the yellow piece was removed. Chances are, one or both of the internal level sensor wires broke. They are very tiny and sitting in fuel for over two decades makes them brittle. If you remove the level sensor assembly, you can inspect it - possibly even fix the wire by soldering it back again... it might buy you some time. Obviously, don't solder near the tank and let the assembly dry out for a day in the sun, first.

EDIT... Oops - you said it reads half, not just "empty". That won't be the wires - a break in those will just cause it to read empty - or at least that's what it did in my car. Unless the calculation that the computer does changed after my year. It's possible that the float arm got jammed or stuck in a certain position when reinserting the assembly. Either way, easy enough to check.

You can also "break into" or "unlock" the computer to check the readings from the two fuel level sender assemblies. Go to the FAQ subforum and look for the thread about unlocking the OBC. There's a great write-up there.

You can also check the level sensor (and wires) using a DVM on ohms at the plug without removing the yellow plastic piece. The small wires are the level sensor wires. This is done just like checking any level sensor/sender.