The hose in your photo that is rubbing on the electrical post I believe is the pressure relief hose. It runs from the fuel filter back to the gas tank. It relieves excess pressure in the system.Use a rag to clean the hose and you will find a Mercedes part number (probably starts with 170) and order that hose, or go to any auto parts store and purchase a fuel hose of the correct diameter (maybe John will post the info for you) and the correct length to make the repair. You can use stainless steel screw type hose clamps in place of those original bands that are crimped on the hose ends. You will need to have hose clamps to pinch the hose off up near the gas tank. Disconnect the end by the filter first and reconnect. Then acting quickly remove the other end and connect the new hose. You will get wet with spilled gasoline so do this in a ventilated area and expect to have some spilled gas.

Read M60A3Driver post after he gets it up with step by step instructions.
Not sure that is the source of the gasoline you smell, but it is a good place to start as the hose in your picture looks damage.