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BF90D fault codes

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HondaHelper

New member
Hey guys, new to the forum and looking for some help. I have a 2013 BF90D BBCJ100…

For the last year or so I’ve had an alarm that will come on once in while when I start the engine but if I shut it off once or twice, the alarm stops and it didn’t seem to effect the operation. It has recently come on full time, accompanied by some strange rpm irregularities. It seems ok (aside from the alarm) up to about 2k rpm, followed by a dead spot up to 2500, then a quick jump to 3k and then up to 4K rpm. I was able to get some MIL codes using the paper clip method, but can’t seem to find out what the codes mean. I suspect either the map sensor or maybe TPS but would love to hear some input from people with more knowledge about these things.

The MIL flash codes I got were; 3 short, 6short, 3 long, 4 short. Possibly 4 different fault codes? Thanks in advance.
 
Hi,
I was hoping someone else with code information more recent than what I refer to would answer. But I'm answering now to let you know that your post isn't being ignored. That and to offer my opinions/ideas about what might be happening.

I am no longer an active mechanic nor have I ever worked on a Honda 90. Most of my experience comes from the auto, truck, bus, heavy equipment arena. At one time I was rated an A.S.E. (Automotive Service Excellence) Master Technician with L-1 and L-2 certifications....among several others.

Not bragging but just listing my knowledge base.

Here's my thoughts about your post:

Looking up the flash codes you listed on the only Honda outboard code sheet I've ever seen, I see three codes that are on that sheet and one that is not. Short 3, short 6 and short 4 are there but there is no long 3.

I initially thought that the long 3 associated with the short 4 might indicate code 34 but, since there is no long 3, there can be no code 34. and no "30" codes are listed.

That leaves the three short codes...3, 4 and 6.

Code 3 = MAP sensor fault
Code 4 = CKP sensor fault
Code 6 = ECT sensor fault

What's interesting is that the possible reasons for each code are identical:
Sensor disconnected
Short or open in sensor wire
Sensor faulty

So....with the odds of each of those sensors being faulty at the same time OR, likewise, each of those sensors being unplugged simultaneously being nil, that leaves "sensor wire short or open" as being where I would choose to focus.

Problem...I don't have a wiring diagram for the BF90D so identifying component connections and wire colors to help you troubleshoot this won't be possible.

However, I can tell you that my experience with troubleshooting similar issues has me thinking that there is a high probability that this could be a grounding issue.

From the very first days of computerized engine controls (yes, I was there....I'm old) we discovered that when an ECM popped multiple or inexplicable codes it often turned out to be a poor ground connection. And, that hasn't changed for the most part. The mantra of pretty much any competent repair shop, to this day, for problems like yours is "check the fuses, powers and grounds".

There are ground wire "bundle points" where ground wires converge and are stacked one on top of the other. On your outboard the largest of these will likely be where the battery ground cable is connected to the engine. Follow that cable from the battery or isolation switch and, at it's terminus, you will find other wires bolted down with it.

The same goes for the positive cable. Follow it (most likely directly to the starter motor solenoid) and you will find other power "feed" wires connected directly to it.

Disconnecting the battery or batteries and taking those connection points off and wire brushing each wire terminal can often result in positive results for an issue like yours. Not always but, even if it doesn't solve the problem, at least you will have done it and eliminated the possibility of a bad connection at those locations. And that's what solving problems like this is all about...
....eliminating the possible cause.

Good luck.
 
Thanks for the reply. Since my original post, I found directions on how to read the codes and a chart explaining what they mean. As it turns out, the codes I was actually getting were; 3(MAP) 6(EBT) 10(IAT) and 24 (ECT 2). You clearly know your stuff as I was also able to determine that 6,10 and 24 are all on the same circuit and by cleaning grounds was able to clear codes 6,10 without them returning. I also cleaned the MAP sensor and have not had code 3 return. I have ordered a replacement sensor for ECT 2 as it’s the only code remaining and is relatively inexpensive.

I will of course start by installing the sensor and see how that goes but I’m wondering if a faulty temp sensor could really be the source of the rpm hunting and stumbling at various stages of throttle or if it’s likely that I have a secondary issue such as perhaps dirty injectors? When I first fired up the boat this year, I did not notice any issues initially but after running for 10 minutes or so, the hunting got worse and worse. I admittedly ran it up with last years leftover fuel so it’s possible that old varnished fuel has worked its way through the system and gummed things up.

Thanks again for any input.
 
Well, I'm glad you've made some progress.

Your reply illustrates the dated material I have no longer applies as the code number meanings have obviously changed in some cases.

I tend to agree that the temp sensor isn't likely the cause of the hunting. I would suspect possibly O2 sensor or, as you say, erratic fuel delivery.

But I'm afraid my input isn't going to be much help as I simply don't have any experience or service info to consult for this engine. No need for me to confuse the issue with uninformed speculation. Although, I AM very good at doing that at times :-0

I do hope that you'll continue to update what you find though as this stuff interests me a great deal and your results will likely help someone else. I will be watching and cheering for you to get it fixed!

Good luck.
 
Just an update as well as something I should have mentioned in my original post.

The code issue is now resolved. I replaced the bad ECT sensor and am no longer getting any MIL codes but the RPM irregularity and hunting is still an issue. One thing I should have mentioned prior is that while tuning my boat up for the season, I replaced the spark plugs, fuel filters and as a “mechanic” friend suggested, sprayed combustion chamber cleaner into the throttle body with the motor running. I have since learned that you should never do this (rookie mistake apparently) and this does seem to be when the issue started. I’m curious if I could have damaged some internal components by doing this that would result in these sorts of symptoms.
Thanks again.
 
I'm just going to riff on some ideas and maybe something will ring a bell for you.....

I have used a product called Berrymans Chemtool to spray into running engines for decades. And, it must be done with care so as not to "slug" the cylinders with liquid because there is the possibility that slugging might cause damage.

However, I don't do that with late model, fuel injected engines. I use water "spritzed" from a spray bottle. Again, using proper technique.

And, the main reason I do that is harsh cleaners are not recommended for use on throttle bodies.

Also, I have found water may be more effective than the combustible cleaner for loosening and dissolving carbon deposits because of the steaming action that takes place.

Depending on what product you used, there's the possibility that you may have actually damaged the molybdenum coating in the throttle body bore and maybe not the engine. That might explain the hunting.

Because, if you had liquid slugged the engine and broken a ring, piston land or valve, that is more likely to cause a steady misfire and not hunting. A cylinder leak down test might be done to dispell any fears about that

Another possibility is that you didn't damage anything at all.

It could be that your gummed up injector theory might be correct.

Adding artificial enrichment with propane gas might be an appropriate test for seeing if it's a fuel flow issue but you may just want to check fuel pressure at about 3,000 rpm first to make sure it's not fluctuating.

Does it hunt badly at idle? If so, and it has a cable actuated throttle (not electronic), it will have an idle air control valve with a gasket and filter screen. Items 10 and 11 in the link:


You could try cleaning the screen and carefully cleaning the valve with throttle body cleaner.

There is also a base idle setting procedure but it must be done according to the directions in the service manual.

You could also remove and clean the throttle body using throttle body cleaner.

I don't know.

But I might even be inclined to first try another set of plugs...NGK... before digging in too deep because using combustible cleaner on a running engine can damage plugs too.

Wish I had a better answer for you.
 
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