One of my 1998 115HP FICHT motors just started having the following symptoms and I am hoping that someone may have experienced and diagnosed it already.
Engine is slightly harder to start than usual - takes maybe 3 tries, I never activate the choke.
At cold start the RPM's run up to about 2400 and stay there for maybe 15 seconds, and the engine sounds a bit rough like it may be dropping 1 or 2 cylinders.
Engine then returns to normal idle (~600 RPM) but is a bit rough and belches a major cloud of blue smoke plus raw fuel and oil mix at this point.
Put her in gear and head out and everything runs perfectly (~5800 RPM WOT).
There are no codes set.
I have not yet run the individual spark plug/ injector firing diagnostics since everything seems good under full throttle
I have not yet ohmed the coils to static test them.
I replaced the spark plugs (7712's) - nothing out of the ordinary after 100+ hours on them, just the usual minor sooty residue though they only saw the bad behavior twice before replacement.
The new plugs were only run for 5 minutes at idle to see if the start-up idle issue was resolved (it was not).
I plan to examine the "new" plugs to see if I can tell which if any cylinder(s) is having the issue.
The engine has been run exclusively on ethanol-free REC90 gasoline, XD50 oil, and OMC 2+4 fuel conditioner for the last 10+ years.
Based on my old "power-pack" motor experience, it acts like a failed coil where a dead cylinder loads up with fuel/oil and then finally catches and runs rich for a moment.
What I do not understand is why the idle at start-up is racing. It is almost like a lean-out situation.
I have 2 motors so I am able to swap out parts to help diagnose the issue.
Thanks in advance for any suggestions.
Engine is slightly harder to start than usual - takes maybe 3 tries, I never activate the choke.
At cold start the RPM's run up to about 2400 and stay there for maybe 15 seconds, and the engine sounds a bit rough like it may be dropping 1 or 2 cylinders.
Engine then returns to normal idle (~600 RPM) but is a bit rough and belches a major cloud of blue smoke plus raw fuel and oil mix at this point.
Put her in gear and head out and everything runs perfectly (~5800 RPM WOT).
There are no codes set.
I have not yet run the individual spark plug/ injector firing diagnostics since everything seems good under full throttle
I have not yet ohmed the coils to static test them.
I replaced the spark plugs (7712's) - nothing out of the ordinary after 100+ hours on them, just the usual minor sooty residue though they only saw the bad behavior twice before replacement.
The new plugs were only run for 5 minutes at idle to see if the start-up idle issue was resolved (it was not).
I plan to examine the "new" plugs to see if I can tell which if any cylinder(s) is having the issue.
The engine has been run exclusively on ethanol-free REC90 gasoline, XD50 oil, and OMC 2+4 fuel conditioner for the last 10+ years.
Based on my old "power-pack" motor experience, it acts like a failed coil where a dead cylinder loads up with fuel/oil and then finally catches and runs rich for a moment.
What I do not understand is why the idle at start-up is racing. It is almost like a lean-out situation.
I have 2 motors so I am able to swap out parts to help diagnose the issue.
Thanks in advance for any suggestions.
