BF50D fluctuating rpm

[brunoleon]

Hello,

I have a BF50D with around 70h.
Bought is last year (second hand) and have been using it without a problem.

This year, I tried at home and then brought it from the coast to its assigned area in the marina, all at low speed and there was no issue.

Once I tried to leave the port, when reaching around 3krpm the engine started to behave weirdly. The engine "accelerated" on it own until around 4krpm and then down to around 2krm again, sometimes it even stalled in the end. We were towed back to the marina because at that time I could not have it to start again.

A few hours later, I then wen back trying to figure out the problem staying on neutral.

Here is a video of the engine at idle (which seems normal to me but it is also my first outboard so I might be wrong):

Another one were it stop on its own once with 3 bips:

And here is a video of the "weird" behavior:

On key point is that I'm not moving the throttle up more when I reach around 2500rpm. It is really doing it on its own.

What I did:
- emptied tank and replace with new fuel (it was 6-8 month old)
- cleanup up fuel-water separator
- tried to pump when reaching this problematic RPM => no change

What I'm gonna do tonight:
- check the 3 sparkles (they are only 1.5year old and may be 20hours so it is unlickely but...)

I have an appointment at the dealer next week, but if I can figure out before that's even better.

Any clue would be much appreciated.

Thanks
--
Bruno

 

[jgmo]

Hi,

That is very strange behavior. It could be caused by a false signal from a sensor or it might even be your ECM failing. I don't know.

You should keep that dealer appointment because it's probably going to need to be connected to their scan tool to figure this out.

It could be running on 2 cylinders part of the time but it seems too smooth to me. I think it would shake and vibrate more if it were doing that. The scanner would help diagnose something like that

If the outboard is less than 5 years old, it should still be under Honda's transferable warranty no matter if it's second hand.

Make sure the dealer checks for technical service bulletins (TSB) and for recalls on that model.

The only thing I can tell you for sure is that you shouldn't run gas that's as old as that unless properly treated with a marine fuel stabilizer like Techron Protection Plus Marine fuel system treatment.

Sorry that I can't be of any help with this one.

Good luck.

 

[brunoleon]

Hello,

I found a dealer availlable today with Dr. H so I will keep you posted later today.

Thanks for having a look !