So I was replacing a front hub on my cousins 02 Grand Cherokee with a 4.0. The only thing I could smell the whole time was gas. I started at the back and worked my way forward. I couldn't see any leaks but the smell appears to be coming from under the hood. He said he has smelt it before but it doesn't smell all the time. Injectors and rail looked dry. Any ideas? Any common problems with these rigs? Thanks for the help.