If you have a gas problem, then you might try two cups of bicarbonate soda....that usually works for me.
Okay, just funnin'. My 149 had the smell of gasoline each time I shut it off to. I found out that the fuel line had a small leak in it. I didn't notice it until I ran the machine because I would always shut the fuel off at the petcock after each use. Check your fuel line to start with and see if you can find any holes at all. Best of luck!
Cub Cadet 123