Volunteered to help my neighbor with his McCulloch backpack blower and now it has me stumped. It is a 30 cc version. After a lot of pulling and choking, etc..... it will run briefly then flame out. Not to run again at all. All the characteristics of fuel starvation/carb problem but when it refuses to run I give it a shot of gas and/or ether and it STILL refuses to run making me think it is spark. The spark seems solid, however, when I remove the plug, ground it and spin the motor over. Even after choking the carb and pulling repeatedly the plug still looks dry when I remove it making me think it is fuel. But it won't run with the shot of ether so that says spark. Carb has been apart several times and is perfectly clean and nothing apparent wrong with it. Diphragms look good and are soft and in good shape. Primer pump works fine. Fuel lines were suspect but have been replaced with no change. Muffler is clean and not plugged. Makes no difference to the problem if the muffler is off or on the engine. Pulse port from crank case to carb is open and clean. Adjusted gap from coil/ignition to flywheel with no change. Engine has good compression and the piston and ring seems fine looking thru the ports. I haven't pulled the jug off yet but that may be next. I'm not new to diagnosing and fixing engines but this particular one has me scratching my head at the moment. It is almost as if the spark is working fine under no load but drops out when there is compression/fuel present. I haven't resorted to buying a coil/ignition yet but I wondered if there is any one with any history of one failing like this or any other ideas....... I'm open to them.