The smell occurs at all levels in the tank. I did notice that there are 3 passages for the fuel to go in the gas flap; 1) obviously the round hole in the center that goes to the gas tank 2)the small hole on the bottom lead by a black plastic hose to the ground and 3)an opening just above the center hole to the gas tank (I do not know where this goes to)
I just filled up the tank this morning and I watched the gas slightly overflow, 99% goes to gas tank in center hole, some went to the bottom hole and some went to the "opening" above the hole. I watched it go to all 3 places. I could not know what I am talking about, but that is what I saw.
9 months ago, I had the following replaced: fuel governor and fuel pump and the hoses look good, but who knows? Why do you think the smell inside the car goes away when it is running?
Does the 300 SEL have a fuel vapor plastic expansion tank like I have been reading for the SL's? I heard that they leak.
I was confused about what you said about the gas flap area. I noticed a black plastic hose coming from the gas flap area. I do not see it passing through the trunk. I do notice when I overfill the tank , some gas comes out of that hose, but I have been slightly overflowing my tank for years, only now have a smelled a strong smell of gas from the back.
How can I smell gas in trunk, but see no leak. Run car and look under car and no leaks any where, but car smells like it will explode in trunk.
Thank you very much for your input.