I have a JD LT155 that when I try to crank it will start but immediately starts smoking and spitting fuel from the exhaust then will die and won't crank again. I took the spark plug out and cleaned it and tried again, also replaced the spark plug but it does the same thing. Any ideas?

Check your oil make sure its not over full.
If so make sure theoil doesn't have gas in it,
If so gas is passing through the carb and into the crankcase ,
Will need carb cleaned

Luck