560SEL Fuel Smell

[Mikebear79]

I can't take it anymore. My garage smells of a light odor of fuel, it's in my sinuses and my clothes even smell like it. My mechanic tightened the banjo bolt next to the fuel pump which was moist, but it didn't take care of the smell. I have noticed that when I release the gas cap, there's a big hiss that escapes (or gets sucked in, not sure) from pressure. Also, there's a pretty strong fuel smell right around the gas cap area. I just had an emissions test done last week and the cap is one of the things they tested and it passed. Not sure what else to do. I read that there's a pressure release valve that can go bad, but it seems like there's two on the parts websites. Which one do I buy? I guess it's the one that goes in the fender from what I've read. Pic attached. - Mike