have cub cadet 26 h.p. will start but will die after 3 to 5 seconds?

I have started and mowed, sveral times this season.It ran great. it will start and run for about 3 to 5 seconds.I have put a new gas filter on it. i checked selonoid on bottom of carberater, it seems to be pulling the stem back down when you cut the key on. I have not tore the carberater down. it is 1050 cub cadet.