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BF115 running rough?

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Tillykid

New member
Greetings, this is my first post and I am excited to be a part of this forum. My Honda BF115 (2014) outboard is running like it’s missing on a cylinder for some reason? It will idle well then when I put it in gear and throttle up, it starts missing and you can feel the power tapping in and out when it misses.
I’ve pulled the spark plugs expecting to see a fouled plug, but they all look the same? Could it be a failing ignition coil?
Any an all advice would be greatly appreciated!
Thanks,
Mike
 
Hi Tillykid,

Welcome.

This could be caused by a few things and might be tricky to troubleshoot.

It could be as simple as just a bad spark plug. They can misfire and still look "normal". If you haven't replaced them in awhile it might be something you could try. I think I would.

Beyond that, it comes down to figuring out is it actually a spark issue? A fuel delivery issue? Or, maybe a mechanical issue?

Yes, it could be a coil not firing but it could just as easily be an injector (or two) not working correctly or being properly "triggered".

A mis-adjusted valve or a weak or broken valve spring can cause a misfire like this.

Additionally, loose electrical connections can cause a misfire.

A loose connector at the ECM, crankshaft sensor, ignition coil or a fuel injector might react to vibration as the engine speed increases.

My point is that, in all likelihood, this will take a well thought out and executed troubleshooting strategy. Something that justifies having the shop manual and, if possible, getting the outboard hooked up to Dr.H to help with the diagnosis.

Sorry, I don't have a silver bullet for you. I'm just offering my thoughts.
 
Thanks for the info! I will start with the things I can do myself first (plugs etc.)
Hopefully it is something simple and I can get back on the water soon!!
 
Yes, hope for the best.

You can buy the official shop manual here:

Honda Marine | Shop Manuals Publications | Honda Power Products Support Publications

publications.powerequipment.honda.com publications.powerequipment.honda.com

Looks like their are at least three listed for the 115 hp so choose carefully.

There are techniques for finding the problem....like using a timing light to identify a cylinder not getting spark or doing what is called a "running compression test" to identify a leaking cylinder at increased rpm....that can help you.

But, as you already said, the simple basics first then work your way through the problem.

Good luck.
 
How old is your fuel? How much have you been using your boat? A lot of low speed use? Trolling?

I would check the water-fuel filters first, if you have the racor external type, dump it in a clear gas jar and see if they is any water or sediment in it.

I agree it is a good idea on the new plugs.

I’d also try running it on an external fuel tank with a high does of sea foam and fresh high octane. Run it at high rpm under load, at sea is best, for 15-30 minutes. See if any improvement?
 
I’ll check the fuel/water separator for sure, I put fuel in it about 6 months ago, but that doesn’t mean it was “good’ fuel?
Thanks for the response!
 
Thanks, I’ve always kept Stabil in my tank over the winter. I had never thought about the bulb squeeze trick! Great idea! I took a sample from my fuel tank, and it is water free. I changed the plugs and fuel and fuel/water separator filters, so tomorrow I will see if that made a difference?
Thanks for all the input! I’ll let you know!
 
Thanks to everyone who commented on my issues! Took the her out this morning and she ran like a champ! Changing the plugs was the ticket I believe!!
 
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