Mysterious Gas Smell

[Roman Kishi]

I have a mysterious raw gas smell inside the passenger cabin. The smell starts only, and only, after driving for about half an hour from a cold start, so after the car warm up nicely. The car runs beautifully, and it’s been maintained by a top notch mechanic, Carlos at JCP for you who live in Northern Virginia

I went thru all trouble shooting/ problem solving things, but to no avail.

- Gas tank cap new
- Checked out the over flow reservoir, changed all the hoses, although had no gas smell in the trunk
- No gas leak any where, gas pump, pipes, injection pump....
- Air/gas mixture is just fine so it’s not running extra rich.
- New valve stem seals
-

Help, any idea
 :?:  :?:  :?:  :?:

Roman
Northern Virginia
280 1969,Signal Red, Auto

[rwmastel]

Roman in Virginia (we have another Roman in Michigan),

You listed all the basics except one thing - the cork seal around the fuel guage sender unit.  Was this replaced?  Typically, the items you list takes care of the problem.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Roman Kishi]

Thanks Rodd, as I mentioned there is no gas smell in the trunk,the gas tank and the pump are 3 year old.

Roman
Northern Virginia
280 1969,Signal Red, Auto

[BHap]

not sure if the 69's have the same setup as 70's, but I have a vapor return line that runs from the overflow/vapor tank to the front of the engine block.  At some point, someone spliced a new piece in the line up near the distributor.  The line runs up the left side of the car and right around the distributor and terminates at the front center of the block - just behind the fan.  The other possiblility is a leaking cold start valve.  Open the hood and watch next time you start the car cold...  it would be a very fine mist and may take a little time to get into the cabin....  I had this on a newer car and could never see "wet" because the mist evaporated too fast...  good luck...

Bob Happe
Pittsburgh, Pa
1970 280SL, white/black 4 speed