Re: 3hp OMC crankcase question Home › Forum › Ask A Member › 3hp OMC crankcase question › Re: 3hp OMC crankcase question mercurymanReplies: 467Topics: 167 June 30, 2018 at 2:38 pm #78730 There is a gasket between main jet and float bowl it can leak and cause rich. It needs to compress when you tighten float bowl.