Small Engines (Lawn Mowers, etc.): JD 185 wont start, spark plug wire, filter need

Question
My JD 185 won't start, it will crank over and try to start and then it will backfire. Occasionally it will start and run fine, but when I shut it down to dump grass it will not start back up. Is it getting to much fuel? Does the filter need to be changed? Do I need to change the plug or is a carburetor problem?

Answer
I will need more information, which engine is on this model?...Is spark present when this no start condition occurs? To check spark remove the plug, ground the threaded portion to the block with the spark plug wire attached. Does a bright blue spark cross the gap when cranking?...Might need someone to help you. When you remove the plug is the electrode wet, or dry?...Tom