My first post here... I'm trying to help my elderly neighbor with her boat.
Unfortunately never worked on a Johnson before.
The engine will start and idle fine. If throttle is increased past 1500 rpm (a guess - no tach) the engine will increase speed then cutout then increase speed and cutout repeatedly. It will do this in gear or in nuetral.
It's difficult to describe in words. It sounds like the rpm limiter in newer cars when you push the pedal to the floor in Park.