I've got a later model Johnson 150 carburetor motor (not Fitch). It's been sitting for a few years and it will start after several tries, then runs great for 10-15 seconds, then dies. It will take throttle up until it stalls. Everything else checks out (new fuel, fuel delivery, spark, ignition, etc.).
It acts as if there's an exhaust blockage. I'm not an expert on 2-stroke, but lots of experience working on 4-stroke. As I understand it, the exhaust tract sends the exhaust out through the crankcase and prop. How does one test my theory of exhaust backup and how would I flush or clear it? It did blow out a chunk of sludge during one of the brief runs before dying.
It acts as if there's an exhaust blockage. I'm not an expert on 2-stroke, but lots of experience working on 4-stroke. As I understand it, the exhaust tract sends the exhaust out through the crankcase and prop. How does one test my theory of exhaust backup and how would I flush or clear it? It did blow out a chunk of sludge during one of the brief runs before dying.