Small Engines (Lawn Mowers, etc.): Primer Bubble

Question
Hi Eric, I hope you had a great Thanksgiving. I'm working on a 3.75hp Briggs and Stratton plastic diaphragm carburetor that sits on the gas tank. Mower model #098902, type 0110 01, code is 98062054. I replaced the diaphragm and gasket and the bubble. The bubble wont pump gas into the carburetor. I put a little gas down the throat as a primer and the engine cranked up and ran perfectly.  The primer bubble just wont work. All part were Stens brand. Can you shed some light on what is wrong and might be causing this? I have ran into this problem in the past and just changed carburetors. I would like to know how to fix this issue if fixable. Any help or suggestions will be greatly appreciated.  Stephen

Answer
Did you remove and clean behind the check valve?  The check valve is behind the primer bulb.

Most likely you will have to replace the seat and check valve with Briggs and Stratton 494409
Seat-Check Valve.

Is the primer bulb fully sealing?  You can submerse in water and press the primer bulb to see if air bubbles come out from around the primer bulb.  

Eric