BF 50 runs very uneven

[PetterF]

Hi all,

We have a Honda BF50 that's about 20 years old and only gets used for a month or two each year.

It has an uneven idle and will sometimes start spluttering and lose power while underway. It struggles to rev properly and won't produce full power until the problem clears.

Last summer I cleaned the carburetors and replaced the O-rings and gaskets. Unfortunately, I only had time to test it at idle, which was still uneven.

The boat is in a very remote location, so I'd like to bring any parts or tools I might need before I go.

What should I check next? I have a vacuum gauge and can synchronize the carburetors, but should I also check the fuel supply? If so, what's the best way to do that?

I'm really looking for a troubleshooting checklist of the most likely causes, so I can research each one before heading out.

 

[jgmo]

Hi PetterF,

I have questions about the issue and not sure what to suggest about what you should be checking.

So far, I understand that the idle is "hunting" or uneven but it will run ok and produce full power at times.

Do you own the shop manual?

Have you ever adjusted the valves or checked timing and timing belt and belt tensioning components?

Is there a fuel/water separator?

Would you happen to have a spare portable fuel tank and hose to swap in for testing? If not, could one be borrowed?

Does it start easily or do you need to crank it for a time before it will fire and run?

When it starts "sputtering" and loses power but then recovers full power again...

...How often does it lose power, say, within a 30 to 40 minute run?
How long does it lose power before it recovers again? Is the recovery always back up to full song and power?

This might be a slog trying to figure out why it's doing this

 

[PetterF]

Hi PetterF,

Hi jgmo,

Thanks so much for your questions.

I realise I really have to be onsite to describe specific symptoms. It's a bit hazey as it was a year since I last saw the boat.

Do you own the shop manual?

No.

Have you ever adjusted the valves or checked timing and timing belt and belt tensioning components?

No.

Is there a fuel/water separator?

Yes. Inspected and even changed last year.

Would you happen to have a spare portable fuel tank and hose to swap in for testing? If not, could one be borrowed?

Good idea. I'll swap it out.

Does it start easily or do you need to crank it for a time before it will fire and run?

Unsure. I seem to remember I have to crank it a few times. But as said, not totally sure.

How long does it lose power before it recovers again? Is the recovery always back up to full song and power?

Last time I tried to use it it lost power after only 5 minutes of a third / half throttle usage.

What I am wondering is if there are some 'standard' go-to spare parts that I can buy now to take with me for any eventual repairs. We are way out on an island without access to a ship chandler, nor postbox for receiving orders/parts.