05 Skidoo Rev w/ some standard engine modifications. Engine has recently burned down twice in last month. Both times were during long pulls. I have 420 jets and plug color looks good. On several occasions I have had to crack the fuel cap and let out pressure befor the sled will start. I have gone through and checked my vent tubes but am not sure exactly how the vent system works and what roll the DPM plays. Also would like to know how the fuel pump works and if there is a vapor lock issue. I don't understand how my tank is filling with pressure. Also then why would this be a problem. I though this would actually help push fuel into the carbs. At any rate it seems like I am leaning out on long climbs because the carbs are not staying full. If any one can help let me now.
