It will start, but then it spitters and sputters for about 5 minutes and shuts down. Sometimes it will start again and sometimes it wil not. I have taken the carborator apart and clean it up. I have changed spark plugs and have put fresh gas in it. I have also made sure it had a spark and that all gas lines are clear. Can anyone tell me what i should check next. The water pump is also working. Thanks

Boating - Johnson