Re: 1996 johnson 150 shuts off running over 4000 rpm
Here's one idea. I had an older Evinrude 100 that did the same thing...at high speeds it would suddenly quit, then start up a short time later. The problem was overheating caused by improper timing. At higher rpms the engine got too hot because of pre-detonating and was automatically shut down by a thermistor in the engine block which prevents the motor from desroying itself when it gets too hot. After sitting with the shroud removed, the engine cools, and running at a lower rpm keeps it from overheating. The other issue may be water circulation being insufficient at higher rpms. Maybe some mechanic out there will give you better insight.
