First, I assume that you are letting the engine warm up for a few seconds before trying to open the choke. It is normal for a cold engine to need the choke gradually opened as it warms. The engine will start to stall and sputter if the choke is left closed too long. I find, it should be warmed up in about 90 seconds, the choke fully open.
Assuming you are doing the start-up process correct, then I would look to see if there is a fuel line blockage. If you have fresh gas and have always stored the engine with the tank dry, you should be okay. Otherwise, there may be gunk (technical term) in either the fuel line, fuel tank or carburetor. Also, make sure the fuel shutoff is fully open.
If the fuel system is fine, (no gunk) then check the ignition system (spark plug and cable). Replace (and gap) the spark plug and make sure that the spark plug wire is solidly connected.
Finally, make sure you have oil in the crankcase and the level is within the operating zone (not too much, not too little, just right).
After that, I give up. Hopefully there is something here to get you started (no pun intended, just happened, honest).
Minnesota's own Bruce B., February 2014
