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Honda BF50 Alarm Mystery

N

nomi

Member
I have late 90s BF50 (with controls) that has been giving me mysterious alarms for at least 6months. The alarms sometimes come & then go on their own. Other times i do something that seems to cure it, but then it eventually comes back. Nothing about these alarms is consistent. Its mostly a solid beep when in gear (and above idle), but ive also had it happen alot at idle & a few times even in neutral. Also, occasionally ive had an intermittent beep beep beep, but usually its solid. Sometimes the alarm wont start til ive been up on plane running for a little bit, but lately its often been sounding almost as soon as i put the boat in gear from startup.

The first time this happened the momentary cure was to slow down off plane to 3000 rpm or less. Lately ive had to slow down all the way to a slow idle or sometimes neutral to make it stop temporarily. A few times it was opposite and would sound at trolling speed, but getting on plane would seem to make it stop. Also, im not certain about this, but the otherday it seemed i could make it stop if i adjusted the trim up slightly then all the way down.

Adjustments that have seemed to make it go away for a longer period of time was a new battery. And another time, just putting an external charge on the battery. Howerever right now the battery is only a month old & rests at 13.5. When the motor is running it jumps up to about 14.5.

I should also mention that the motor will usually eventually bog down if i keep running thru the buzzer. The time it takes to bog down is not at all consistent; sometimes quickly, but sometimes it doesnt bog.

I pointed a heat gun at the motor and cant see anywhere its getting hot. Also, i tend to doubt it is because this beep often starts when the motor has only been running for a minute. I've only owned the boat 2 years and the temp & pressure lights have never been operational.

Ok now heres the most confusing part. Today i disconnected (at the motor) the temp sensor wire, oil pressure wire, and the trim sensor. IT STILL BEEPED!?

The only way i can permanently stop the alarm is by disconecting either of the two wires going into alarm itself under the console.

I would take it to a mechanic, except i was told by one that this model is too old to be hooked up to the computer to identify the issue. So its gonna need to be figured out on the water thru trial and error.

ANYBODY WITH ADVICE THAT CAN HELP ME SOLVE THIS IS MY HERO!
 
You have a faulty trim gauge sender, your model sounded an alarm as described when the motor is tilted up and you try and accelerate. Disconnect the trim sender and bridge I think light green/blue and the black, if that doesn't work try other combinations, you will not harm anything, it's been a while so I am not positive on the colors. Alternatively, replace the trim sender unit.
 
You can't just disconnect the sensor,you need to bridge the orange and black on the engine haness plug. The wiring diagram I have is a hard copy in one of my manuals so can't send a link.
 
iang6766 said:
You can't just disconnect the sensor,you need to bridge the orange and black on the engine haness plug. The wiring diagram I have is a hard copy in one of my manuals so can't send a link.
Click to expand...

Sorry im an electrical layman; can you explain what i need to do to "bridge"?
 
Okay, disconnect the trim sender, then look at the 3 pin plug that you have disconnected it from and bridge the orange and black terminals inside the plug, alternatively you can leave the trim sensor plugged in, cut the harness to the sensor and bare and twist the orange and black wires together.
 
iang6766 said:
Okay, disconnect the trim sender, then look at the 3 pin plug that you have disconnected it from and bridge the orange and black terminals inside the plug, alternatively you can leave the trim sensor plugged in, cut the harness to the sensor and bare and twist the orange and black wires together.
Click to expand...

Didnt solve the problem.
 
Explain what you have done so far, there is nothing else on that engine that will cause the alarm you are experiencing , the other option is to remove the trim alarm module altogether.
 
iang6766 said:
Explain what you have done so far, there is nothing else on that engine that will cause the alarm you are experiencing , the other option is to remove the trim alarm module altogether.
Click to expand...

I went pretty thoroughly into everything I've tried in my original post. I had the temp, pressure, & trim sensors all disconnected simealtaeosly & STILL had the alarm. Unless im somehow screwing that up, this must be some kind of faulty electrical issue, right?
 
I dont want to lead you down the wrong direction with my suspicions, but I've put in a new battery twice in under a year & thats fixed the buzzer issue both times for a period of time. Either that is causing something computerized to reset or else there is some sort of voltage/charging or bad ground issue.

These are just my guesses. & im not a very experienced handyman, so take them worth a grain of salt.
 
Okay so i just took it out & got the buzzer sounding, then started disconnecting everything in that cross connect box. If I disconnect a specific 1 of the two white wires, the buzzer will go away. But if i try to increase rpms further, the motor still boggs down.
 
Update: the white wire i disconected runs from regulator/rectifier. And the other end comes from the 15a fuse. Fuse is fine.
 
Try running the engine at various rpm and use a DVOM to check for AC voltage leaking through the charging system. I don't know what the maximum allowed is for your system but I would suspect anything over 0.025 volts AC may be causing problems. Don't forget to set your meter to the AC volts scale and simply measure across your battery posts.
Let us know what you find.
 
Well, it sure looks like you have way too much ac bleeding through the rectifier. BUT...and this is a pretty big one....

.....I don't have enough knowledge or information as to what is acceptable for a bridge rectifier charging system. I was expecting a much lower voltage but I could be wrong.

In my mind the rectifier should be converting ALL the AC volts from the charge coil to DC volts and the regulator should keep it at 14.5 vdc or under.

It would be great if we could talk a forum member that has a 50 to measure theirs for comparison.

ANYONE WITH A 50 hp want to help??
 
Your problem might be the small panel in the control box that might be shorted out due to salt water ,the one with the green light and overheat light.You might have to open up the box and disconnect this panel and retry the motor. Just a thought.
 
Jimmy Robichaud said:
Your problem might be the small panel in the control box that might be shorted out due to salt water ,the one with the green light and overheat light.You might have to open up the box and disconnect this panel and retry the motor. Just a thought.
Click to expand...

!!!!!

Okay i disconecres the the wires going into that indicayor light box.

Dont want to declare premature victory, but it seems to solve the alarm issue.

But is that mean that little light box is my issue? Or are we just indirectly disconnecting the alarm?

The reason I ask is because with that box unplugged, my key did not work tk shut the motor off.
 
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