1999 115hp Johnson runs sweet one minute and hopeless the next

[ozforce]

I have the above engine that starts from cold and flies around at 5000rpm for 40 mph for a while. Then I go to idle for a while to pick up a passenger and when I move the throttle to fast; it runs as if it only has one cylinder working. After a few attempts I idled up to the ramp and went home. What is happening please?

 

[racerone]

Model # is ?

 

[ozforce]

Model # is ?

J115PLEES SN 04695989 02/99

 

[racerone]

Perhaps it is overheating and going into S.L.O.W. mode.-------When was water pump serviced, if ever ?

 

[ozforce]

Perhaps it is overheating and going into S.L.O.W. mode.-------When was water pump serviced, if ever ?

Water pump serviced and cooling circuit is good. We suspect stator, trigger, ECU but with absence of diagnostic equipment we are reluctant to throw money at this if we are wrong.

 

[oldboat1]

You can measure spark with an open air tester (cheap) to test ignition system. Look for 1/2 inch sharp spark. You can check fuel for contamination. Sample fuel at the bottom of the tank. In a glass jar, any water will be seen at the bottom. If you put any solvents in the tank to "clean the system", debris may have contaminated carbs (requires thorough carb cleaning).

 

[racerone]

No item called an --ECU----On that motor.------Ignition module or " powerpack " is found on that motor.