Have you looked for the leak with the engine running? I had the raw gas smell too, finally "caught" the leak in action. In my case it was the cold start valve intermittently leaking where the injector mounts to the flange/body. The years had taken their toll, and the injector was slightly loose in the body, which allowed it to move a minute amount. When it moved it leaked.
Your leak could be coming from any of the fuel lines or fittings. The cold start valve is only active when the engine temp is below 35dC, and only operates for a few seconds during start-up, but there is constant pressure on the valve even when not operational.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.