Gas licking in front of the rear axle
 

It usually happens on cold morning when I start the car and stops when car worms up. Could this be just a seal ?
Its dripping from the place circled on the picture.
How can I diagnose this and fix it ?

http://www.russianquarters.com/mitbok/images/3.jpg

REMOVE THE FIBERGLASS COVER FOR THE PUMP PACKAGE (AHEAD OF RIGHT AXLE) IT IS HELD IN PLACE WITH FOUR 10MM PLASTIC NUTS.
START ENGINE WHILE STILL COLD AND LOOK AT THE FUEL PUMPS (USE A FLASHLIGHT NOT A DROPLIGHT,YOU DON'T WANT ANY FIRES!)
FUEL IS PROBABLY COMING FROM THE END OF ONE OF THE PUMPS
MF

Are there any seals or tubing that can be replaced or am I looking at a new fuel pump. Any one else had this problem ?

It was real bad on my SL. And not just cold starts only. 129s have that same fiberglass guard to protect the fuel pumps, but it can collect a lot of fuel before dripping out of the weep hole. Result: Fumes galore! My wife drives the car, so she tipped me off to the problem.

Turned out to be one of the OEM clamps that held the hose in place...just loosened enough over a period of time to develop a trickle leak at the hose end.

Total DIY repair cost: $0! Had spare clamps in my toolbox...:)

You will probably need to replace the rubber hose that connects the filter to the "hard" piping. I do not remember if it is the hard piping that goes to the fuel tank or toward the engine. This hose leaked on my E320 until I replaced it with a new one. It will be real evident where the leak is once you remove the fiberglass cover.