Small Engines (Lawn Mowers, etc.): lawn mower, pawn shop, gas tank

Question
I bought a lawn mower at a pawn shop it started fine and run great. Its been sitting in my shed for 2 months and now i am trying to start it and it will run when the bulb is pump or if you start it and push and hold the bulb in. I checked the gas lines. It seems to be getting gas but wont stay running. What could cause that?

Answer
needle and seat stuck under carb. float,  or sticky.
put fresh fuel in tank.  remove what is in first. put some carb.  cleaner (say like you can buy at auto store) into gas tank. put a heavy dose in .  after it runs and stays running ,  remove it and replace fuel.  
try that..... if that don,t work out.... carb has to come apart and cleaned out and serviced .