My machine stops running about 3 to 5 minutes after starting - sputters and then stops. After a few minutes it will start but still sputter. After sitting for an hour or more it starts and runs normally for a short whilke and repeats the problem. The ATV is used very infrequently; sits for weeks at a time. Only has 340 miles and 90 hours use. Haven't cleaned fuel tap screen yet - could this be the problem - inadequate fuel flow? Or, carb float valve intermittently stuck?

 

Maybe the gas cap vent tube is plugged. Try running with the cap loostened up or removed.

 

I had a problem like this on an older dirtbike I once had- was a bad cdi coil. it would heat up and fail- once it cooled off, it would run fine for a few minutes again until the coil got too hot.

could also be a fuel filter, but I'd think you'd experience it a lot sooner and more consistant if it were the fuel filter.

wouldn't hurt to remove the carb and go through it- and replace the filter anyway.

I would also try to squirt a little ether in the airbox when it starts to stall- if it starts to run with the ether, then you have a fuel problem. If it just continues to stall, check your spark / ign system.