When my Bayou 250 sits for just an hour or so, it will not start. I put fresh 93 octane gas in it,new spark plug, and soaked the carb overnight in cleaner. I have to take out the air cleaner and hold my hand over the air inlet side of the carb. It will then start, but it will not idle. The brand new plug has black deposits on it already, after only one start. HELP!!!