My Artic 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.    

if it loading up there is a reason for it.
which normally means a cracked float or trash in the carburetor around the float needle valve.

as you know, as fuel enters the bowl, the floats raise and push the float valve into it's seat and shut off the fuel.
so the problem has to be in the carburetor or if you have a fuel assist pump on this model then the pump may be defective and be pumping too much fuel.