Gas/ Fuel smell in the rear driver's side wheel well - 2009 528i, 190k miles N52
 

Lately I have been smelling gas/fuel from the driver's side rear wheel well. The smell is more prominent after driving the vehicle, even short distances. I've searched around online forums but have not really found any good means to try and trace the smell, as mostly results come up for E90's.

• I figure it would be the fuel vapor/evap canister that is usually on the sides of the rear bumper in most vehicles. Due to the age/mileage of the vehicle it could be that the canister may be the culprit, although NO codes come up on my BMW specific OBD-II Scanner.
• A fuel leak on the pressure sensor? Some suggested to remove the rear seat and check the seals for the fuel pump/pressure sensor. Is this common on E60's? That would explain the faint gas smell after the vehicle as sat for a few hours, but is very pungent immediately after a drive.
• Injector #5 was replaced by a Rock Auto branded injector about 8k miles ago. There is NO fuel smell in the engine bay or anywhere else in/out of the car except the driver's side rear tire.
• I don't typically overfill the tank when refueling, I let the pump stop by itself and do not continue to pump past that.
• The fuel cap is about a year old, replaced with an OEM cap - however the rubber gasket seal is green instead of blue like the one on the vehicle. It fits perfectly and locks/clicks just like the previous blue rubber seal one.

I plan to replace the brakes/rotors all the way around in two weeks when the brake wear sensor and a few other components arrive. With the wheel off I plan to remove the protective wheel lining to inspect to see if any fuel lines may be corroded or if I can maybe see the fuel/evap canister.



There has not been a decrease in performance, fuel consumption, loss of MPG nor have I noticed the fuel level go down any more than normal. I keep my 528i well maintained with the usual common fail areas/components already addressed and replaced. I just noticed the fuel smell for about week now whether parked in the garage or out in the apartment parking lot.


If anyone has any advice, tips, suggestions or material I can review to try and trace this mysterious fuel smell that would be great. I just a fuel pump/fuel filter replacement on my 04 Miata that was not fun! Unfortunately the Miata is not best for daily driving as it has an issue randomly not starting (immobilizer/ecu problem I suspect).

Hoping this is a relatively easy fix or if it's something simple as an evap canister being wet - would I need to worry about it? Or just live with the small gas smell?

V/R,

MD

Check under the rear seat first.

the 5 series are notorious for the driver side fuel pump taking a shit. Normally it starts with the hat. I believe it's the hpfp. You'll see when you lift up the rear seat there is the hpfp and lpfp on passeneger side

FYI, the HPFP is run off of a chain on the engine. The fuel pump (lpfp) is under the passenger side rear seat and the fuel filter assembly us under the driver side rear seat.

I had this same problem and fixed it by replacing the fuel filter and pickup that's under the DRIVER side rear seat.

There's lots of articles, but one thing you really want to do is DISCONNECT THE BATTERY. You know that humming that your car does at random times when its just sitting there? That's the fuel pump getting ready for a drive. You don't want that spraying your interior when you've got it apart.

Thank you everyone. I replaced the fuel sending unit/filter assembly and the leak was fixed. Looks like it had a hairline crack in it in the nipple that connects to the hose. Unfortunately I didn't buy the special metal ring removal tool and although I thought I chiseled it all the way tight, when I filled up past 3/4 of the tank fuel leaked a lot at the gas station. had the car towed and sat in my gravel driveway with oil absorb to catch some of the spilled fuel. I have since bought the tool and should arrive today. Overall it wasn't too terrible, I just highly recommend buying the $15 tool than the hammer/chisel/screwdriver method.

Thanks for the update.

Thanks for the update. Glad you figured it out. I've never used the tool but then again I've always used a pry bar to do spend the locks on and off.

Getting if off wasn't the problem, it was locking it back into place. When I tried with the chisel/hammer method it worked, however towards the end it shifted the filter assembly to where the float would not read the fuel correctly. Once the actual removal/installation tool arrives I plan to have someone hold down the plastic fuel assembly while I turn the tool to lock it in place. I did confirm there was no leak after replacing the faulty unit (a new Bosch part and Genuine BMW O-ring was just under $80 on FCPEuro) so no it's a matter of tightening down the metal lock ring in place correctly.

I replaced the brakes (pads/rotors) all around and it's due for an oil change that i'll tackle next weekend. Otherwise I hope to keep this car running to at least 200k. It just hit 190k a week ago.

So the new metal ring removal tool worked like a charm. Removed and reinstalled it correctly and now no leaks. Thanks to everyone for the help and assistance throughout this entire ordeal.



Hope this might help others in similar situations.