i have an 07 and i have the same porblem, i go thru a gallon in approximately 1.5 hours of putting around trails.
i know why though, its not because of being on the throttle, or wrong carb setup, its the damn overflow. if i forget to turn of the petcock, and drive back to my house from where i ride, i will dump almost the whole tank of fuel out that tube. every time i stop after a ride, it pisses out about 10 seconds. some sledders i hang out with say to reroute the line back up the the fuel cap, but if i remember right, this cant work on a gravity fed sytem, because once the level in the return tube and tank are the same, it wont go up the tube any more. plus this seems like asking for a severe flood..