Small Engines (Lawn Mowers, etc.): Starts but will not continue to run., needle valve, o rings

Question
    Starts but will not continue to run.I have a craftsman mower. It has not run in a couple of years. Model # 143.996704. The bowl and the needle valve seat were really narley. I replaced the needle valve,  seat,  and 3 O rings.. I'm not sure I have the O rings on the main nozzle in the correct location. Float seems to be working okay. I am getting spark and the bowl is full of gas. Runs for about 3 seconds after I spray quick start in.  Help.

Answer
Did you blow compressed air from an air compressor through all the carburetor orfices?

On a positive not, since in will start you know the timing, compression and ignition systems are fine...so it must be a dirty carburetor.

Let me know if cleaning the carb again fixes the problem.  BTW, I have had to clean carburetor two or three times before the would work correctly.

Eric