Hi,
I am trying to help a friends daughter who owns a 1984 280SL 2 door. I am pretty experienced with restoring US made cars, but this is my first Mercedes. The problem is gas fumes inside the car. I have removed the panel in the trunk behind the gas tank, and can see the tank. I can smell gas fumes around the tank. So far I have "sniffed around" and looked for leaks to find none. Before I go any deeper, I thought someone could clue me in if this is a common problem with these cars, and see if someone has a diagram of the fuel system. I don't have a manual, and since this is a freebee for a friend, I don't really want to purchase one at this point. Ive noticed a small plastic tank above the gas tank, no idea what this is for. It has several rubber hose lines going to it, and all look in good condition. The tank itself looks very good. I noticed that the rear panel definitely has been removed before. She's not the original owner, so there may have been an issue before that the previous owner had fixed. I'm looking into that.

Any suggestions are much appreciated!