I have a 2013 Troybilt Pony riding lawnmower. Previous use was mowing for about 1 1/2 hr per mow. Today, I was mowing larger lawn that took about 4 hrs. I fueled up to complete lawn and it started fine. Drove it about 15 yards to finish last small piece and mower died. It would not restart. When I got back to house about 30 minutes later I tried to start. Engine turns over but will not startup. Only thought is when I fueled up something got in the tank. Fuel can is clean so it didn't come from the there. I didn't notice any debris in the fuel tank. Any suggestions before I return the mower?