Honda BF-50 alarm as soon as key is turned.

My Honda BF-50 is sounding a continuous alarm the moment I turn the key. I don't even have to start it up. The alarm stays on until I shut off the motor.

I just took it in for routine tuning two months ago. When I put my boat back in the water at a public ramp, and motored over to my marina (hour trip), it was working just fine.

When I took it out a week later, the alarm started sounding. It may have been low on battery, but I recharged it from the dock for days. The alarm sounds every time I take it out now, even though the engine starts and runs fine.

Engine oil level is fine and clean.
Pee-hole is peeing fine.
Removed thermostat to ensure water is flowing.
Battery is 12.45V when motor off, 11.9V with motor running.
I checked the warning light on the remote throttle (oil, overheat), but they don't light up. (course they might be burned out)

A couple of friends have suggested the drop in voltage might point to an alternator problem.

The fact that the alarm sounds the moment the turn the key - even without starting the engine - rules out several possibilities, in my opinion. It surely can't be an overheating problem, and it surely can't be an alternator problem. But I'm no expert.

Failing anything else, what I'm tempted to do is pull the electrical connector apart and test which wire is live with a meter, but I don't know how to do that. I can't even be sure which leads are the power and which are sensors.

The green guy (this is not my motor, this is from Google, but it's the same connector):



Suggestions welcome.

I think it's fair to assume there's an electrical gremlin causing your headache. If you pull that main harness apart, I'm not real sure you're going to help isolate that issue. More likely I think, will be electrical connections on the motor itself, and the first I would have a look at would be the temperature sender wires. They're on the left/port side up near the top rear. You may have to remove the timing belt cover to get to them. If they are found clean, keep going, unplugging and replupging, checking to see if you've quieted the alarm as you go. I can save you the trouble of messing with those down along the bottom on that side. They're all about the tilt and would not cause your issue.

Best of luck!

Alan Hicks said:

I think it's fair to assume there's an electrical gremlin causing your headache. If you pull that main harness apart, I'm not real sure you're going to help isolate that issue. More likely I think, will be electrical connections on the motor itself, and the first I would have a look at would be the temperature sender wires. They're on the left/port side up near the top rear. You may have to remove the timing belt cover to get to them. If they are found clean, keep going, unplugging and replupging, checking to see if you've quieted the alarm as you go.

Click to expand...

Thanks. I'll check them out.

I guess I don't know if I've found it until I clean it and plug it back in and the alarm stops. If it's crimped lead, I might never find it.

Alan Hicks said:

I can save you the trouble of messing with those down along the bottom on that side. They're all about the tilt and would not cause your issue.

Best of luck!

Click to expand...

Actually, some buds on my sailing forum have suggested that the tilt probe(s) could just as easily be the culprit as any other.

The tilt sensor wiring is forward (anything's possible, but I would not be suspicious of those), near where the power cables for the tilt motor are run. One thing I do see is a broken or sticking arm on that sensor. Might as well check that while you're at it.

The wires I was speaking of are all related to the power for the tilt trim. I doubt anything there would ever trigger an alarm....

Just stating the obvious that battery voltage with engine running should be somewhere around 13.5v to 14.5v. Further investigation on the charging side required.

After rereading the original post, I believe there's a problem here-

"Battery is 12.45V when motor off, 11.9V with motor running."

What exactly will take some trouble shooting. Might be the cause of the alarm, but maybe not. It's going to need attention one way or another.

Hm. Neither owner's manual nor service manual even mention an alternator.

There is no "alternator" like you might see on an auto for instance. The components of an outboard "alternator" are mostly hidden under the flywheel, only there are no brushes in play. There ARE magnets. So same only different.....

The end result is that they are able to keep your battery charged - if working as designed. My experience has been they are pretty good at doing that pretty reliably. Not much trouble with that system.

Alan Hicks said:

There is no "alternator" like you might see on an auto for instance. The components of an outboard "alternator" are mostly hidden under the flywheel, only there are no brushes in play. There ARE magnets. So same only different.....

The end result is that they are able to keep your battery charged - if working as designed. My experience has been they are pretty good at doing that pretty reliably. Not much trouble with that system.

Click to expand...

Hm. OK. Alternators on cars fail regularly. A component that needs replacing.
Sounds like it's not so simple on an O/B - or too simple. Not sure how to check it.

Did you say you have access to a "service" manual? That should provide more than enough detail. If you're competent with a volt/ohmmeter, not that complicated really. You'll be looking for open or shorted coils of wire, and checking the rectifier. But I'll bet you find a crudded up connection in the process.....

Do you have the correct Honda manual?

I have the Owner's Manual. I thought I found the service manual online, but no.

re: Online Service Manual, for whatever reason the powers that be will not allow the boatinfo address to be posted. You could do some searches on that, or send me your email and I'll send you the link.

OK, I pulled it out and tested it. It seems to show connectivity on ALL leads, so I'm sayin; it's blown.

I've ordered a new one, but it'll be two weeks.

My motor won't run without it, so if I want to go out, I'll need to put the bad one back.

I'll just disconnect the alarm.