Reply To: 1956 Johnson 30 hp won’t accelerate boat up on plane!

[Don]

Sure, it is totally possible to be running on one cylinder even though it has spark and compression on both…. Like Brooke says, always return to the basics when we get confused, starting with a new set of plugs. Try running the engine with those inline neon spark testers or checking with a timing light while running…Perhaps it is running on two at low speeds, then dropping a cylinder/spark at higher RPMs. Anything most problems are usually simple things we have overlooked.