I'm getting really strong raw fuel smell in the cab. I've looked all over the engine and don't see any leaks, but the smell appears to come from the engine compt. If I go to recirc mode on the ventilation, or am moving, the smell goes away. I've inspected under the hood, no signs of leak, fuel lines are tight, and the smell happened before I put anythng on the truck, though I noticed it more after the down pipe mod. Loosened that, checked it, checked the bottom, used antiseize, no change. I'm stumped, any ideas?:help