Re: Need help diagnosing Evinrude 9.5 problem

[Don]

OK, I want to get back to your original running complaints to make sure I understand exactly what is going on…
First, let me know how you are running the engine. In a barrel/test tank, or have you actually had it running on a boat? Like others have said, trying to run/tune/diagnose these engines while running in a tank will lead to false conclusions and added headaches.
I will proceed "assssuming" you have run the engine on a boat. Does the "stutter" occur at high speeds as well as low speeds? If so, is the stutter only a momentary (a few seconds) thing while running at high speeds? I’m asking this because I am trying to point you in the right direction, electrical/ignition faults are usually momentary that result in quick/sharp drops in RPM. Fuel faults are usually bogs or a smoother loss of RPM.
You mention replacing points/condensers. Did you run the engine before doing the ignition work? If so, did the running characteristics change before and after doing the ignition work? Who did the ignition work, you or the repair shop? This issue could be something as simple as a bad spark plug, even though the plugs are probably new…I would try another set of plugs before going much further, use Champion J6C plugs gapped at .030".
You mention that the engine won’t idle well, but slight choking helps keep the engine idling. You are correct, there might be more than one problem creating these issues. I guess I would attack the high speed problem first to see if that solution will solve the idling problem.
The key to success, and minimal frustration/expense is to never over look the simple stuff….Most problems are fairly simple, but we really confuse things and create our own problems when the basics are over looked and we dive into complex areas.
Is there any way you can post a video of the engine misbehaving at high and low speeds?