Dear Experts,
I have a Johnson Evinrude 90 hp year 2001 engine that was behaving badly mainly after warming up. I sent all the electronics to a specialist and the verdict was the stator. The spark coils were rebuilt.
After installing it, the main problem disappeared. But when revving above 3400 rpm, it would misfire from time to time. After reading quite a bit, I realized that it could be the CDI or the coils. I bought the CDI and the optical sensor from CDI electronics and two new sets of coils (original).
For my total sadness, after replacing it, it started to misfire again as I had replace nothing.
The first mechanic that I discussed told me that it should be the stator, as this rebuilding process is never perfect, and it might solve the problem temporarily, but it will come back later.
I contacted the guy who rebuilt, and he said his service would make it even better than the original. But he gave me two hints: It can be the flywheel or the cover of the optical sensor.
I am a physicist and though a theoretical one, I think If I understood the basics of how that sensor works, I could try to figure out what is going on myself.
For me, important information is that the misfire happens above 3400 RPMs and if I fix the rpm, like 4000 RPMs, it does not happen with a given frequency. It may run for one minute or two, then misfires, then after three minutes misfires again.
The engine is running smoothly when it does not misfire, has a perfect idle, carburetors were all done recently, spark plugs are new.
I live in Brazil, and the problem here is that the mechanics have very few tools. I see people talking about strobe lamps, etc. Unfortunately, they do not even know what that is.
They fix things basically by trial and error.
Could anyone help me? I will very much appreciate it.
In the attachment, is a picture of the engine's plate.
Thank you in advance for any hint!
Demetrio Filho
I have a Johnson Evinrude 90 hp year 2001 engine that was behaving badly mainly after warming up. I sent all the electronics to a specialist and the verdict was the stator. The spark coils were rebuilt.
After installing it, the main problem disappeared. But when revving above 3400 rpm, it would misfire from time to time. After reading quite a bit, I realized that it could be the CDI or the coils. I bought the CDI and the optical sensor from CDI electronics and two new sets of coils (original).
For my total sadness, after replacing it, it started to misfire again as I had replace nothing.
The first mechanic that I discussed told me that it should be the stator, as this rebuilding process is never perfect, and it might solve the problem temporarily, but it will come back later.
I contacted the guy who rebuilt, and he said his service would make it even better than the original. But he gave me two hints: It can be the flywheel or the cover of the optical sensor.
I am a physicist and though a theoretical one, I think If I understood the basics of how that sensor works, I could try to figure out what is going on myself.
For me, important information is that the misfire happens above 3400 RPMs and if I fix the rpm, like 4000 RPMs, it does not happen with a given frequency. It may run for one minute or two, then misfires, then after three minutes misfires again.
The engine is running smoothly when it does not misfire, has a perfect idle, carburetors were all done recently, spark plugs are new.
I live in Brazil, and the problem here is that the mechanics have very few tools. I see people talking about strobe lamps, etc. Unfortunately, they do not even know what that is.
They fix things basically by trial and error.
Could anyone help me? I will very much appreciate it.
In the attachment, is a picture of the engine's plate.
Thank you in advance for any hint!
Demetrio Filho