Fuel smell in trunk

[EricTi]

Hi,

My trunk has a bad smell of fuel but there does not seem to be a leak

Replaced the rubber of the sender plus silicone around it

Any leads ?

Thanks

[halboyles]

PM me with your address and I'll send the fuel sender sleeve that also allows fuel vapor leakage in the trunk.  This is gratis.

Fuel Sender Tube Sleeve Replacement.pdf

[Son of Marty]

To much to cover here, in the search box at the top of the page, enter fuel smell and a couple of hundred threads will give you your answer. Also welcome to the faq.

[Martin Nobbs]

40 minutes ago, halboyles said:

PM me with your address and I'll send the fuel sender sleeve that also allows fuel vapor leakage in the trunk.  This is gratis.

Fuel Sender Tube Sleeve Replacement.pdf 368.01 kB · 3 downloads

I literally replaced the fuel line on my fuel sender sleeve last night and was surprised how loose the hose was. Is there any chance you have another one available?

[1936spyder]

46 minutes ago, Son of Marty said:

To much to cover here, in the search box at the top of the page, enter fuel smell and a couple of hundred threads will give you your answer. Also welcome to the faq.

Exactly; the search function is your friend! The faq board has been around for almost 20 years so there’s an extremely good chance that this topic might’ve been covered before ?.

 

Regardless, the O-ring for the sender could be a culprit as could the hose (s), depending on what model you have. The correct style hoses are covered in a woven fabric that will obviously hide any cracks that might have developed in the rubber hose itself so the degradation of the hose might not be readily apparent. I just replaced mine recently for that very reason:

[stephers]

Check the filler neck hose as well, especially on the bottom side at the bend, they tend to crack there     Is your vent system still in place and if so, check all those hoses and connections

[halboyles]

58 minutes ago, Martin Nobbs said:

Is there any chance you have another one available?

Absolutely!  Just PM me with your address.

[John76]

6 hours ago, stephers said:

 Is your vent system still in place and if so, check all those hoses and connections

This is a common oversight on the hunt for the trunk gas smell.

Should have a small hose connecting the rubber filler neck (un-cracked) to the plastic vapor tank above the right rear shock tower.

This has another hose (hard to see cuz it's in the back) that connects through a plastic line to the charcoal canister in the engine bay. The charcoal canister has a hose that connects it to the air cleaner....so all fumes from the tank get sucked into the engine and not your nose. Caution, do not plug this hose. The gas cap is sealed, and this is the vent for the gas tank.

[calw]

A little bit of "it depends" here. 

 

Early cars had no vapor tank or charcoal canister.  Just an aluminum overflow line.  It connects the big rubber fuel-filler part (connects tank to filler) under the right tail light around the trunk floor to where it exits under the license plate. 

 

Likely places for stench in those cars are the sender O-ring, the fuel line connection (use Hal's sleeve) or via cracks in the rubber fuel-filler part ($$ to replace with new, which should be a nice supple rubber part).  Using a newer fuel tank in one of those cars also requires plugging the tank vent line.  For the record, the sender o ring starts life as a normal round-cross-section O ring, not the flattened crusty oval shape O ring that you'll remove when replacing it.

[John76]

If you are pulling the tank, replace the open foam stuff that the tank seam sits on. This retains moisture and is sure to cause rust and pin holes in the tank. Use a closed foam (weather strip) or gas-proof, non-hardening sealant.

[EricTi]

Some pictures of the current situation

Fuel tank has been replaced some 15 years ago

[EricTi]

O ring is new

[calw]

that's the early version that I referred to above. There's no tank vent pipe, or at least I can't see one in the photos. 

 

The metal line from the top of the big black rubber part behind the gas filler is the only venting in this scheme,  it goes around behind then down along the rear edge under the trunk boards and dives out thru a little hole in the floor, thru a cone shaped rubber grommet bit.  If it's not exiting the trunk, you're venting to the trunk.  If it were to be clogged, same problem.

 

The rubber part is itself possibly cracked, hidden between the inside and the side of the fender.  If it isn't flexible like new rubber, watch out for tiny cracks. 

 

The fuel line connection at the tank is the most likely thing though.  I don't see a clamp at the flex end near the tank, and the rubber hose should probably be replaced for a few $ from the local auto parts store- it has to be fuel proof tubing, not windshield wiper hose(!).  The official BMW fuel line with braided covering is, of course.  I got one of Hal's excellent gratis sleeves, but ended up using some fuel line that was a tight fit on the tank end and required gentle heat to fit on the metal fuel line at the other end instead.  The original plastic fuel line that I think I see in your photo probably wouldn't take the mishandling to do the same, hence you need the spacer to account for the differences in diameter between tank outlet and fuel line (probably NOT one of BMW's most brilliant design points).