BF10D running rough

I have a 2014 Honda 10 HP (BF10D) outboard on my dinghy in the Carribbean. I have had no issues with it since new. Every year when we haul out for hurricane season I flush with fresh water, run engine out of fuel, change oil and fuel filter. This season I had no issues until I refueled a week ago. Now it will not idle after it warms up. It runs fine on open throttle, and I can keep it running with it partially choked. I just drained and pulled the carb off for the first time and the bowl was clean, all of the orafices appeared to be open. I spayed carb cleaner thru as many of various channels. I removed cleaned and replaced the main jet tubes. Reassembled. Refilled with fuel and started it on the first pull. Ran a few laps around the harbor with open throttle and when I returned to the boat it idled for a minute or so and the died. I could restart it by partially pulling the choke. Runs fine when the revs are up, but when I go back to idle I must pull the choke out a bit to keep it running. Any more tips on how to trouble shoot this. I believe that last fuel that I purchased last month was a high octane fuel from a marina in Hampton VA before sailing south ( I presume that they carried the premium fuel to avoid the ethenol.). I have not added a stabilizer to that fuel as I need to purchase more. Advice would be appreciated.

Regards, Daniel

Hi Daniel,

First off, I don't have experience with this outboard. But I'm assuming it's very similar to the 9.9 models. Boats.net doesn't list 10 hp beyond 1997 and that's the only reference I have.

Anywho...
Check out the link I attached and see if your carburetor isn't very similar.


https://www.boats.net/catalog/honda...bf9-9dk3-sha-2007-and-later/carburetor-manual

I'm particularly interested in the choke components (items 20 & 12), the accelerator pump assembly (items 11 & 14) and the idle mixture screw assembly (item 4).

If those are the same on your outboard, then we will be on the same page for discussion.

It definitely sounds as if you MIGHT have a blockage in the idle circuit as pulling out the enrichment valve seems to help. But it can be a little more complicated than just removing the mixture screw and blowing into the cavity.

So let me know if your carburetor matches the one in the link and I will try to give you some targets to pursue.

Hello,. Yes, my carburator appears to be the same as in the link that you sent. The motor was purchased in the French island of Martinique.

One other thing that I noticed is that it does not seem that the pump on the outboard side of the carburator is actuated. The throttle at idle just makes contact with the pump. When I open the throttle it does not appear to move. I can push it down and release it manually and it appears to work but moving the throttle does not seem to engage it. But I'm not sure what in the linkage is actually adjustable.

Any advice will be appreciated.

Thanks, Daniel

Well, I'm not sure why the linkage doesn't actuate the accelerator pump but it may be because the pump piston is just a bit tight in the bore. That's easily remedied with some WD-40 and a little 800 grit sandpaper.

If you want to take the carb back off and remove the float chamber I can walk you through some things that you probably missed when you cleaned it before.

If you you just want to try to get it to idle well you could remove the mixture screw without taking the carb off and try hosing out the passage with carb spray. It will probably need to come out anyway to properly clean the carb.

The silver plated limiter cap is glued on with Loc-Tite and a soldering iron can be used to heat it and remove it from the mixture screw. This will pretty much ruin the cap as it is made of plastic and will melt. Alternatively, you can use side cutters to "crunch" it off but you'll run the risk of snapping off the head of the screw and that makes it very difficult to back out of the hole.

The mixture screw head is actually made to snap off easily to prevent tampering so you need to be careful if you plan on reusing it. I actually recommend having a new screw assembly on hand before beginning but that's your choice.

I also recommend having a gasket new set available if you want to do the "Full Monty" cleaning of the carb. The jet-set oring at the top of the carb throat is a critical component and is easily damaged once disturbed.

After removing the limiter cap, back out the idle mix screw. It does no good to count the turns out since it's almost impossible to tell when the threads are disengaged. This is because the little oring that seals the cavity acts as an annoying little lock that makes it a pain to get the screw out. You have to defeat that oring's interference to back the screw all the way out. This will take some prying and manipulating with a small, pointed object. I have a particular little pick I use to do this but, because the screw head is so easily broken off, it's still a great idea to have another one standing by.

Caution: When loosening the screw threads you need to make dang sure that the threads are completely disengaged before prying on the screw. When you think it's loose, screw it out about 25 more turns just to be sure.

Once the screw and spr8 is out, you can hose the passage and see if that works. If not thought, you'll probably be taking it out again to do a full cleaning.

More later.

Sorry about my poor proof reading of my previous post. Spr8 really means SPRING.

Normally I would point out that a complete new carb might be the easiest, most cost effective option for dealing with one of these finicky little carburetors. At $150 it's not too
terribly more expensive than purchasing all the small items plus gobs of carb spray to properly clean one of these. But in this case I can't tell you the part number because it's a European model outboard apparently. While I suspect that the 9.9 carb will work just fine and I would try it if it were me, I can't promise you an exact "performance fit" doing that.

Thanks for all the supporting responses. Right now I am in Bermuda and we might be departing for Antigua tomorrow or Thursday (6-8 days offshore). So unless there is a change of plans I will park this until I can get to Antigua, and can also make sure I can get any replacements for things I destroy in the process. I like the idea of a replacement carb and then cleaning this one up as a backup. A dinghy is pretty essential transport when you live on a boat in the islands. I check back in with you once I can pick this up again.

Thanks and best regards, Daniel



QUOTE=jgmo;703324]Sorry about my poor proof reading of my previous post. Spr8 really means SPRING.

Normally I would point out that a complete new carb might be the easiest, most cost effective option for dealing with one of these finicky little carburetors. At $150 it's not too
terribly more expensive than purchasing all the small items plus gobs of carb spray to properly clean one of these. But in this case I can't tell you the part number because it's a European model outboard apparently. While I suspect that the 9.9 carb will work just fine and I would try it if it were me, I can't promise you an exact "performance fit" doing that.[/QUOTE]

Ok Daniel,
Thanks for the feedback and timeline. I have to tell you too that I'm going in for major back surgery on December 10 and will likely be "out of action" for a time myself.

Yes, the replacement carb and then cleaning your old one at your leisure is a solid plan for a cruiser such as yourself.

I love the Honda twin outboards and their mostly rugged nature but the little carburetors on the post 1990 models are a pain when they need cleaning. Honda power equipment publications has a HONDA MARINE CARBURETION MANUAL that is a BIG help to anyone doing their own maintenance.

Here's the link:

https://publications.powerequipment.honda.com/marine

The carb manual is near the bottom as you scroll down.

Bon Vente!

jgmo said:

Sorry about my poor proof reading of my previous post. Spr8 really means SPRING.

Normally I would point out that a complete new carb might be the easiest, most cost effective option for dealing with one of these finicky little carburetors. At $150 it's not too
terribly more expensive than purchasing all the small items plus gobs of carb spray to properly clean one of these. But in this case I can't tell you the part number because it's a European model outboard apparently. While I suspect that the 9.9 carb will work just fine and I would try it if it were me, I can't promise you an exact "performance fit" doing that.

Click to expand...

Hello JGMO, I hope you are doing well. We did get a good carb clean-out in Antigua. My attempt was just not good enough to get the right little bits unplugged. It did well the rest of the season, until the very end when I did experience a couple rough runs.

I would like to buy a spare carb, like you mentioned above. Can you recommend the best source for this in the US?

Thanks. sv BeBe

Hi Daniel,

Good to hear from you.
As I stated before in the quote, I don't have the precise service information for your outboard that would point us to the exact fit carburetor.

If you order one from the U.S. and it doesn't work properly or doesn't fit at all, returning it for a refund will be problematic at best.

Having said that, if you still want to try to order one, I would contact www.boats.net and ask for some advice. They carry most of the Honda parts for models up to about 2011 and possibly later. I am positive that they ship worldwide.

If you can provide them your outboard's frame serial number they might be able to reference the correct carburetor for you.

I wish you fair winds and calm seas

I have two questions:

When you say that you are still having "rough running", is it as before? Meaning that, does it start fine cold with the choke pulled out but then begins bogging down after running for a short while?

And....

Have you ever replaced the thermostat?