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High Speed Mis Fire on Johnson Outboard 150

E

eroloff

New member
I have a 1992 Johnson 150 that consistently misfires at 4200 RPM. Below that RPM, the engine runs well, comes up on plane well, and appears to be running well on all 6 cylinders. At first I thought the problem might have been a fuel delivery/restriction issue, so I replaced all fuel lines from the tank, including the pickup in the tank itself, all the way to the VRO pump, which I also just replaced as well. The problem still continues, and I'm now wondering if there is a rev limiter that's causing the engine to misfire, or if there is a faulty temperature switch that might be tripping a rev limiter. I hit 4200 RPM with lots of throttle range left, and no matter how much farther I push the throttle down, I can't get over 4200 RPM.

FYI, the power pack and all 3 coil assemblies were just changed 2 months ago to fix a different issue from last year. Spark plug leads are 2 years old and are the correct CDI leads (grey and black wires). Spark plugs are the correct Champion spark plugs recommended by OMC/BRP.
 
The optical sensor was replaced with the power pack and coil assemblies. When the power pack was replaced, the mechanic told me that he checked the stator and it was fine. I've noticed that when the engine is cold, I can run it up to 4500 rpm before it misfires and limits me from going any higher. When the engine is warm, I can only get up to 4200 rpm, and even worse after I pull a tube for a bit, so temperature is definitely affecting the problem.
I read in CDI ignition's manual that the original 1991 and 1992 stators from the 150 and 175 hp models would only work with the original power pack, and that replacement power packs have to be paired with a replacement stator (again, if the motor is a 91 or 92, which mine is). Does anyone know if this could be my problem? The stator on the engine is the original from 1992. Is there any chance that the problem could also be a failed temperature sensor triggering a rev limiter in the power pack or a bad rectifier that is drawing too much current from the stator and not getting enough charge to the power pack as a result?
 
eroloff said:
The optical sensor was replaced with the power pack and coil assemblies. When the power pack was replaced, the mechanic told me that he checked the stator and it was fine. I've noticed that when the engine is cold, I can run it up to 4500 rpm before it misfires and limits me from going any higher. When the engine is warm, I can only get up to 4200 rpm, and even worse after I pull a tube for a bit, so temperature is definitely affecting the problem.
I read in CDI ignition's manual that the original 1991 and 1992 stators from the 150 and 175 hp models would only work with the original power pack, and that replacement power packs have to be paired with a replacement stator (again, if the motor is a 91 or 92, which mine is). Does anyone know if this could be my problem? The stator on the engine is the original from 1992. Is there any chance that the problem could also be a failed temperature sensor triggering a rev limiter in the power pack or a bad rectifier that is drawing too much current from the stator and not getting enough charge to the power pack as a result?
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Stator does not matter or have to be matched, but if you have cdi electronics power pack you need to use the cdi electronics trigger
 
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