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2017 Honda BF100A - Alarm at Startup

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Whitnasty

New member
Good morning!

Long time lurker, unfortunately first time poster... To give a little background to provide as much information as possible... Purchased boat with a 2017 Honda BF100A in July of last year. Engine currently has 270 hours on it. When I purchased the boat, the previous owner had a leak around the fuel sender gasket on the fuel tank. Took the boat out and the engine sucked up some water into the engine on the first day. Alarm ON-OFF-ON-OFF began continuously beeping. Was able to get the boat back home quickly and discovered the water in the fuel issue.

Drained the tank, re-sealed the fuel sender gasket and ended up replacing basically everything in the fuel system. Low Pressure filter, low pressure pump, high pressure filter, high pressure pump and filter basket, pulled the VST and thoroughly cleaned the varnish out. Things seemed to be working normally after that for quite some time.

I installed a NEMA2000 compatible display on the boat and noticed that the engine was never really getting up to temperature like it should. Pulled the spark plugs and they were pretty dark indicating it was running rich. Replaced all 4x spark plugs with Iridium plugs and replaced both thermostats. The block thermostat was in pretty rough shape and was stuck open. After replacing both thermostats, engine temperature was up where it should be. Also replaced the new battery with a bigger battery around this time, group 27 up from a group 24 battery. No issues for a few months after that.

A month or so ago, I began getting what sounded like the fuel/water alarm when starting the boat... Turned the boat on and off a few times and the alarm would eventually go away, and the engine would run normally for the rest of the day. Basically every time I would take the boat out after this, it would alarm right at start up. Power cycle a few times and it would go away, and would run all day without issue. I thought I was possibly get a false failure from the fuel/water separator or the float was possibly sticking, so I purchased a new cup/float assembly and installed it yesterday. Started the engine up, same alarm going right at start up. Garmin display showed the Check Engine light and showed a "Level 2" warning. Let the engine run for a few minutes with the alarm sounding. Went into neutral and revved the engine up and about 3-4k, I noticed the engine kind of skip or bog for a second. Had to re-start the engine about 6 times until the alarm finally cleared. Revved it in neutral and everything sounded good. Re-started the engine about 4-5 more times after this and the alarm never returned. I know there is no water in the fuel system now, and it has been thoroughly cleaned. Replaced my transom mount fuel/water separator yesterday as well and there was no visible water/contamination in the can.

Does anyone have an idea of what could possibly be going on with this engine? This is my first personal boat (old man had multiple growing up), and I have thrown quite a bit of money and time at this thing since purchasing it. I have been reading it could possible the o2 sensor, but not quite sure. This has been a learning experience to say the least!

Any and all help on possible next steps would be greatly appreciated.

Thanks very much!
 
Hi,

I don't have any experience with the 100A but am interested in what you may discover so I will be following this thread. All I can suggest is that you may want to look into getting a scan with the Dt. H software if possible.

I will say that, while I read the above, O2 sensor crossed my mind but I have no proof to warrant you going that direction other than the running rich for a time may have contaminated it in some manner and that I know Hondas have had plenty of O2 problems.

One last thing I'll say is that, since it's "new to you" and you've already seen cooling system issues, you might want to do a pre-emptive strike and replace the waterpump kit. Even though hours aren't high, time does take a toll on pumps.

Good luck and please keep us updated.
 
jgmo said:
Hi,

I don't have any experience with the 100A but am interested in what you may discover so I will be following this thread. All I can suggest is that you may want to look into getting a scan with the Dt. H software if possible.

I will say that, while I read the above, O2 sensor crossed my mind but I have no proof to warrant you going that direction other than the running rich for a time may have contaminated it in some manner and that I know Hondas have had plenty of O2 problems.

One last thing I'll say is that, since it's "new to you" and you've already seen cooling system issues, you might want to do a pre-emptive strike and replace the waterpump kit. Even though hours aren't high, time does take a toll on pumps.

Good luck and please keep us updated.
Click to expand...

Water pump/impeller kit was replaced when I pulled the VST and cleaned everything. The one that I removed was in pretty good shape, but went ahead and replaced everything for peace or mind.

Question: Could a clogged fuel vent cause the engine to throw a code/check engine light? Yesterday when I got it to finally, start, without the alarm, I had removed the fuel fill cap. Not sure, if that had anything to do with it or it was just a coincidence that it cleared after removing the cap. Re-installed cap and could not get the alarm to go off again.

Thanks very much for the help, will keep everyone updated!
 
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I suppose a clogged vent causing the mixture to go lean and possibly creating a misfire or detonation that would effect the knock sensor (if equipped) could cause a problem like that. But again, I have no experience with that.
I think that the best you could do there is make sure the vent is clear and see if the issue continues or not.

Good luck.
 
jgmo said:
I suppose a clogged vent causing the mixture to go lean and possibly creating a misfire or detonation that would effect the knock sensor (if equipped) could cause a problem like that. But again, I have no experience with that.
I think that the best you could do there is make sure the vent is clear and see if the issue continues or not.

Good luck.
Click to expand...
So I completely removed the fuel fill line and the vent line (they were old and need to be replaced anyways). Started the engine with both removed and the alarm was present on the first crank. Let it run for a minute and tried to Rev the engine in neutral and it would hesitate/bog around 3000rpm. Shut the engine off, and restarted it, and the alarm was no longer present. Let it run for a while, revved the engine and everything acted normal. Killed it and restarted it about 5-6 more times and could never get the alarm to sound again and engine revved like expected. I am noticing some black "soot" around the threads of the o2 sensor on the water jacket. Just can't understand why the code eventually clears, and once it does, doesn't seem to return that day. I disconnected the o2 sensor and started the engine and got the same "level 2“ warning on the nmea2000 display. Plugged the o2 sensor back in and the alarm/fault cleared.

I'm sure the easiest and best course of action is to take it somewhere to get the code read and figure out for sure what's going on, it's just a hike to the nearest dealer for me.
 
Yeah, I hear ya. It's a pain not to be able to at least retrieve the code. There's just not a big enough market for the code reader people to make something affordable for these outboards.

Although, I know a few folks on this forum have the Healtech scan software and say it works well.

Unplugging the O2 may have given you the information that you need but it would be nice to know for sure before popping for a new sensor. Because, I hear they're dang expensive.
 
jgmo said:
Yeah, I hear ya. It's a pain not to be able to at least retrieve the code. There's just not a big enough market for the code reader people to make something affordable for these outboards.

Although, I know a few folks on this forum have the Healtech scan software and say it works well.

Unplugging the O2 may have given you the information that you need but it would be nice to know for sure before popping for a new sensor. Because, I hear they're dang expensive.
Click to expand...
Yeah seriously, about $330 from boats.net.... not a cheap change. The wrench for removing the o2 sensor should be here today so I'm going to pop it out and take a look at it this afternoon. Guessing it may be in the process of failing or could be an intermittent issue.

Will keep everyone posted!
 
You can try cleaning the O2 sensor with throttle body cleaner, sometimes works. But I would read the codes.Google pulling codes on a Honda outboard, it's the same for all of them
 
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