Small Engines (Lawn Mowers, etc.): poulan pro PPB250E, rubber gasket, maintenance manuals

Question
wont start i have replaced the fuel lines i have good fuel i have spark i taken off the carb and went through it even made sure the rubber gasket between the carb and cylinder

Answer
Were the carburetor diaphragms soft and flexible?  If the fuel lines were bad then odds are the carburetor diaphragms, which are made of the same material, are bad as well.

Did you dis-assemble and clean the carb?  There are repair/maintenance manuals available online from Walbro, Zama, and Tilliston carburetors.

How old is the unit?  Have you checked the engine compression?

Eric