Small Engines (Lawn Mowers, etc.): tractor wont start, engine model, model type

Question
hello i own a craftsman riding mower model #917.257730 it wont stay running it will turn over but wont start, sometimes it will run then others it wont. we cleaned carburetor replaced spark plugs and fuel filter, oil and oil filter, checked fuse and cant figure out why it wont start. cant find no help online anywhere. thanks for your help

Answer
Do you have spark?  I tried looking up the engine model number but the Sears parts lists does not provide the engine model number.

Do you have a Briggs engine?  If so, what is the model, type, and code number of the engine?>

Let me know if you have spark.

Eric