I have a Sears lawn mower 6.5 HP, model # 917.388521. The mower starts and runs for 2-3 minutes and dies. I can prime with the bulb and it will start and run for another 2-3 minutes. I have taken the carb apart and cleaned in carb cleaner then plew out with compressed air. There are no adjustable parts in the carb. The float is plastic with no adjustment for the needle valve. The mower seems to not be getting enough vacuum to keep the fuel in the bowl. Please help.

Hi,
When you had the carb apart, if you tuned it upside down was the float level? The is a seat above the inlet needle that can swell and cause your problem Part #398188. A non-venting gas cap can, also.
Peace,
Clarke

Installed a new needle and seat.. That took care of the problem.
Thanks for the help