A craftsman mower did not start at all. I cleaned out the carburetor, cleaned the passages on the bowl bolt. The air filter is clean, the fuel drips in a 1/8" stream without the bowl attached. After all of this, A few pulls will get the engine to start, and it has run as long as ten seconds or so before dying with a puff of blue-ish smoke. The spark plug has a .03" gap but looks a little oily. I cleaned it up with little change in behavior.