Sticky float or seat, my mxz670 is .016/.018 had it at .030 got bad gas mileage, (50 miles to 10 gallons,gap plug at .016 now I can go 100 miles) my mxz was tricky to start till i learned only use primmer to start it,, one two meny squrits will flood it. sounds like your float sticking I would say something is dumping gas.(also depends on witch way the wind is blowing with a ski doo He Haw) Crash dummy