Keep in mind, the manual states failure of the (stator) charge coil test results in stator replacement OR correction of ground fault issues in wiring / connections. Again, removal and inspection of (new) stator and associated wiring revealed nothing unusual.
I agree with your idea there may be multiple issues. Hard to say what may have been done before I bought the boat, of which I remain unaware. I know from the condition and array of disconnected wires under the dash, which I thought were remnants of old electronic gear (fish finder, radio, etc.) the old key switch had been messed with. That’s why I replaced the key switch and re-wired it (hopefully correctly). I’m guessing; the previous owner encountered problems with the (MWS?) system warning, since the alarm horn and check engine warning (on tach) were not operating correctly. Check engine light (vacuum) came on (stayed-on) even during pre-check and if engine was NOT running. Changed vacuum switch anyway. Tach quit registering RPM’s soon after. Btw, a new tach solved the warning system issues, but RPM’s still do not register, even after installing a new regulator/rectifier.
I’m becoming more and more convinced, there is a grounding issue somewhere, including in the starting / charge circuit. As soon as the weather warms a few degrees (hopefully tomorrow), I’m going to attempt checking (by-passing) existing ground circuits to see if it makes any differences.
Lastly, I want to say that I sincerely appreciate your sensing my frustrations AND persistence. Although I’m doubtful either is worthy of praise, a few kind words of encouragement go a long, long way to keep me hanging-in. I submit that comments like “RIP” do little to help anyone nor solve the issues. Probably better to say nothing!
Anyway, Thank you, SCM.