My 6 month old GT5000 with the 26hp Kohler will not stay running after backfiring. I dismounted the tractor to remove debris from my path, and the safety device on the seat shut it off. Well, it backfired on the shutdown, and the problems started. It restarted and made it partially around the yard where it died. I figured I was low on fuel or vapor locked, so I topped it off and let it cool for 20 minutes. It restarted and ran for a few minutes before quitting. I let it sit overnight, and it starts and dies out now. I pulled the feed line to the carb, and no fuel is coming from the pump when cranking. The filter is full of gas, and the thing only has 13 hours on it. I think the backfire busted the diaphram in the pump. Ever seen something like that? Thanks, Rudy.