Okay.....as you can tell by my posts over the past year, this motor is giving me a run for my money....literally. I took the boat out this past weekend to give it a run down since the fall duck season when I properly winterized it and stored indoors for the winter. The engine starts fine, idles fine, will run all day from idle to 1/2 throttle. When I went WOT for about 1,000 yards give or take, I lost a cylinder, if I backed it down the cylinder would come back, or if I shut it off and restarted it would be normal again. If I ran it a WOT again, it would repeat itself but would drop the cylinder in shorter distance.
It really seemed like a spark issue. I put new plugs in every year, even though they get less than 100 hours of run time on them so these plugs were pretty new NGK's. After pulling the plugs the 3rd cylinder, which was the one not operating properly as you could tell by the residue on the plug compared to the 1st and 2nd cylinder. Overall though the 3rd cylinder plug looked good.
I decided, that since I do not know if the coils and wires had ever been replaced, that was the most likely issue. I ordered new coils and plugs and switched to the Honda factory Denso plugs. I got them tonight and installed them all, gapped the plugs to the specs etc.... I had done this once before on a BF25 of similar vintage, this is a BF40.
I took the boat out after install to give it a shakedown. Started immediately, warmed up, and off I went. Made it about the same distance as before, except.....this time the engine COMPLETELY SHUT OFF. No warning lights, sounds etc. Oil indicator light was green, water shooting out the tell tale and no other noises sounds or the like. I did the same thing, all of a sudden I had a loss of power, which felt like a loss of a cylinder due to spark, but the engine shut off completely. The motor will start just fine every time and operate at idle to half throttle, I can still go WOT, but the symptom repeats itself.
So......It still really seems electrical to me and the only thing I can replace now is the following electrical items. 1. The coils (exciter, charger) under the fly wheel or 2. The CDI unit itself.
Things to know about this motor...1998 BF40, originally was a remote controlled version, that I converted to a tiller. I did not change the CDI in that conversion. This has me a bit suspect that is the problem. Next....I don't know if the timing belt has ever been changed, it looks good, but I think it is about due. Could timing be causing this issue?
I don't believe it is a fuel delivery issue, last year I replaced the internal fuel filter, installed a new 60 GPH Honda external fuel filter, it has new fuel line and bulb. All fuel connections have stainless clamps or zip ties internally. Last year I replaced all the float needles in the carbs, clean the carbs, synced the carbs as well. I also did a cylinder compression test and all 3 cylinders were very healthy. Lastly I adjusted the valve clearance as part of regular maintenance when I did the carbs.
So...before I bit the bullet and spend $600 - $800 on a new timing belt, exciter and charger coils and a CDI unit I would really appreciate your feedback. I wish I would have recorded video of it tonight but I was so pissed off I didn't think about it.
Thanks for your endless help,
Eric
It really seemed like a spark issue. I put new plugs in every year, even though they get less than 100 hours of run time on them so these plugs were pretty new NGK's. After pulling the plugs the 3rd cylinder, which was the one not operating properly as you could tell by the residue on the plug compared to the 1st and 2nd cylinder. Overall though the 3rd cylinder plug looked good.
I decided, that since I do not know if the coils and wires had ever been replaced, that was the most likely issue. I ordered new coils and plugs and switched to the Honda factory Denso plugs. I got them tonight and installed them all, gapped the plugs to the specs etc.... I had done this once before on a BF25 of similar vintage, this is a BF40.
I took the boat out after install to give it a shakedown. Started immediately, warmed up, and off I went. Made it about the same distance as before, except.....this time the engine COMPLETELY SHUT OFF. No warning lights, sounds etc. Oil indicator light was green, water shooting out the tell tale and no other noises sounds or the like. I did the same thing, all of a sudden I had a loss of power, which felt like a loss of a cylinder due to spark, but the engine shut off completely. The motor will start just fine every time and operate at idle to half throttle, I can still go WOT, but the symptom repeats itself.
So......It still really seems electrical to me and the only thing I can replace now is the following electrical items. 1. The coils (exciter, charger) under the fly wheel or 2. The CDI unit itself.
Things to know about this motor...1998 BF40, originally was a remote controlled version, that I converted to a tiller. I did not change the CDI in that conversion. This has me a bit suspect that is the problem. Next....I don't know if the timing belt has ever been changed, it looks good, but I think it is about due. Could timing be causing this issue?
I don't believe it is a fuel delivery issue, last year I replaced the internal fuel filter, installed a new 60 GPH Honda external fuel filter, it has new fuel line and bulb. All fuel connections have stainless clamps or zip ties internally. Last year I replaced all the float needles in the carbs, clean the carbs, synced the carbs as well. I also did a cylinder compression test and all 3 cylinders were very healthy. Lastly I adjusted the valve clearance as part of regular maintenance when I did the carbs.
So...before I bit the bullet and spend $600 - $800 on a new timing belt, exciter and charger coils and a CDI unit I would really appreciate your feedback. I wish I would have recorded video of it tonight but I was so pissed off I didn't think about it.
Thanks for your endless help,
Eric