What are the symptoms of your problem.

Does it run but act like its starving for fuel?
Will it start at all?
If it runs can you see air bubbles in the fuel line or is it all fuel?
Are you certian there is no abnormal restriction to fuel flow from the tank?
Are you sure you have the pump diaphram and the gasket in the right location?
Is the needle valve lever set correctly? (should be about parrallel with carb body)
Is the needle valve diapram and gasket in the right spot.
Did you disassembe and clean the carb? ( may have a piece of junk in it)