(E39 540i) Very strong gas smell after driving for an hour

[Siberstein]

Hey so this has been plaguing my car for a couple years now, but it hasn't been getting driven much so I haven't made too much of an effort to find the problem.

Basically, the cabin fills with a strong smell of gas after I've been driving on the highway for more than an hour. Its strong enough to give you a headache after a few minutes and I can almost guarantee I've lost a few brain cells because of it, lol.

It doesn't seem to be be affected by how much gas is in the tank, or whether or not I'm beating on the car. The smell isn't especially present outside the car, or in the engine bay.

I have had a shop check for exhaust leaks, and have checked under the rear seat and its all dry. No obvious gas leaks under the car. The cabin air intake filters are removed and I've taped over the holes in the engine bay just in case but that did nothing.

Any help is appreciated! I don't really know where to go from here.

[jclausen]

I would remove the rear seat the two inspection plates and inspect the fuel pump/sender on the passenger side and the left fuel tank sender sniff around down there, you have seal rings and the various hose and electrical conections. Look for staining also

[dworthy]

Have the evap system smoke tested for leaks, for that too will take time for the vapor to build as you indicate.

[ross1]

With the windows up and the climate control system operating you have a very slight positive cabin pressure due to the fan running so I think the fumes emanating from the tank senders is unlikely but still worth looking.
Your fuel lines in the engine compartment pass almost directly in front of the driver's side air intake. You mention the cabin filters are removed(why?)and the openings taped over.
My suspicion is fuel weeping in the engine compartment and being drawn in, taped openings or not. Check carefully for any stains around the fuel line connections.

[Siberstein]

Hey sorry for the late reply, so the blower motor doesn't work and is never running. The cabin filters were removed because the filter housings became so warped over the years there was no seal around the filter and they were basically doing nothing besides looking awful, and at one point we figured that could be the source of the smell. I just checked the fuel lines and there are no visible leaks in the engine bay, however next time the smell comes back I'll give it another quick check just in case.