I put an HSR 42 on my 07 660 rhino and it ran fine for a while other than I need to go smaller on the main jet. Went to start it today and when I watch the inline fuel filter it has fuel in it until I start to crank the engine to start it then the fuel drains back into the tank. If i get the rhino running on starting fluid fuel will come back into the filter and stay there until I try to start it again. I rebuilt the pump over the winter and it seemed to work fine until now. I'm not finding a vacuum leak either. Does anyone have any ideas as to what could cause this?