1999 Suburban fuel smell

[fishiniowa]

I have a 1999 Suburban, I have a strong fuel smell in the cab that comes and goes, it's almost too recent to tell for sure . I know I had a similar problem with a 1994 K1500 but it went away. I remember something about a charcoal filter in the front of the engine compartment. Anyone have any other ideas. It's a 1500 with the 350, 4x4, 99,000 miles. Thanks

Dave