My Arctic Cat 400 auto after it is run for awhile and we pull over for a bit when we go to start it again will start pumping out gas from the over flow by the key switch. (this also happens when it is just sitting there) then it is hard to start must have throttle all the way open. It will load up and back fires then will start. last time it happened we only went 15 miles that day.  We do drive them in high elevations 8250 or higher. Does anyone have any idea? it has been back to the dealer 3 times for this problem they have checked the carb and replaced the fuel filter.  

Sounds to me like its building up to much pressure in the tank.Check the end of the of which is acutally a vent hose that comes out down around the front diff. Could be plugged.Sometimes those need to be replaced because of that problem.I had that problem in the winter and was because ice was blocking end of hose down near the front diff. Try that and see what happens. You could also try pulling hose off and running it to see if the hose is the problem.