Honda BF25A Missing at Idle

Hello everyone. I have a new to me Honda 25 HP year model 2003. This engine is clean as can be and only has 137 hours on it. When I test ran the motor I noticed it idled rough. I asked the owner about it and he said it had not been run in a few weeks and that he always used stabil in the gas and sometimes ran seafoam mixed with the gas and this seemed to help. He also said he always ran the carbs dry after each use.

After getting it home I replaced the fuel, checked the fuel filter etc. However I noticed that with it idling when I pulled one plug wire off at a time the middle one made no difference. I tested the spark and it was just like the other two. I squirted a little gas in the sparkplug hole, replace the sparkplug and started the engine, it started right up and purred like a Honda should for a few seconds until the gas I squirted in was burned.

I suspected a plugged carb so I ran a small container of concentrated SeaFoam through the fuel line, tapped around on the carb but nothing helped. Now I know I probably need to pull the middle carburetor and give it a thorough cleaning.
I have a service manual and it shows pulling the whole intake manifold to get to the carbs.
Is it possible to just remove the air breather and linkage and only remove the middle carburetor?
I'm open for any other suggestions also.

Thanks.

You can remove just one, but it is a pain. You will need a 1/4" swivel and long extension.

However...I recommend following what the manual says to do....I have found that if you have one carb in trouble, the others are not far behind, so do them all.

Mike

I went ahead and tried removing just the one carb but you were right.....it is a pain and definitely not intended to be removed in this manner. I didn't get it fully removed before I bailed out and put it back together as I found it. I decided to take it to my local marine mechanic and let him do a complete clean and/or rebuild of all 3 carbs. That way I know I am starting with a fresh carb job.
Thanks for the help and advice.

Sounds like a good idea. While getting this work done...be sure to get a new fuel filter and new spark plugs, if they are not already new. That way, you are starting off fresh.

Be sure to get the NGK DR7EA spark plugs not any substitute.

Also, the previous owner always ran the carbs dry. Just running it out of fuel does not get all of the fuel out. Once you run it out of fuel, drain the carburators. You should only need a rag to catch the fuel that comes out, but it will build up over time.

Also, do not forget...if you are starting your motor on a hose to be sure that the ear muffs are very tight and the intake that is in the horizontal plate above the prop, has duct tape over it to avoid sucking air. In any case, do not run it for a long time on a hose....they will tend to overheat....the ear muffs are never tight enough.

Enjoy your new engine.

Mike

Thanks for the help Mike. I'll take your advice on the fuel filter and plugs. I will be sure to tape up that extra intake hole when flushing with the hose and muffs too.

Sounds like it is really important to get ALL of the fuel out of the carbs, I have never done this with any engine I've ever had and maybe I just got lucky but I've never had any problems, but all my other engines have been pre 1995 2 stroke engines.
Is it just more critical on the newer engines to get the carbs completely dry?
I suppose with less (or no) fuel in there the chances of pluggage are less?
I would like to know the reasoning behind running the carbs dry and draining them. This has been a good learning experience for me and hopefully one that will avoid problems in the future as much as possible.
Thanks again.

The passages / jets in these carburetors are very , very small to begin with.-------3 carburetors on a 3 cylinder motor when usually on a 2 stroke there is but 1.-----------Then there is our modern fuel that has a short shelf life.-------So the fact is when fuel is left in them they tend to plug up.

My local Honda mechanic did a thorough cleaning of the 3 carbs and said all the internal parts looked good so none were replaced. I ran the motor a few times and it seemed to run much better. Yesterday I took it out and noticed that after running awhile when I slow down to idle the engine is idling very, very rough and would eventually die and took some coaxing to get started again. Once I got on plane it seemed to run ok but when I slowed to idle it ran rough once again.

I pulled the carbs off myself this time and inspected them very closely. All 3 are spotless as examined with a flashlight and blowing carb cleaner through the ports.

I am wondering if one or more of the float valve seats in the carbs are leaking and flooding the engine at idle?
Does this sound reasonable or can anyone think of what else may cause the rough idle?

Thanks to all.

Check your spark plugs and see if one of the plugs is a lot blacker than the others. If so, then maybe that float needle could be leaking.

Do a cylinder drop test and remove one spark plug wire at a time as the motor is running and see how the engine responds. Use an insulated pliers to do it. As you remove the plug wire, hold the cap up near the spark plug and listen for the ticking of the spark (that will let you know that you have spark). When you pull the plug wire away from the plug, the motor should drop noticeably in rpm. If it does not drop, that is your problem cylinder.

Hope they/you inspected the idle jets (jet set) (real thin tube going up the center of the carburator) for cracks. You need to use a magnifying glass to see them.

Or...some debris could have gotten into the carbs and plugged one of the idle jets...or some dirt was still in one of them and it dislodged and clogged. The fuel for idling goes up through the very thin tubes. You can not be sure if you have them thoroughly cleaned due to their construction. I almost always replace them if they are clogged.

Mike

As Mike says, replacing the "jet set" with new is the way to go. Also, if you guys were taking the jet out and then putting it back in without replacing the "o" ring at the top, then it is probably not sealing properly.

Additionally, if you are experiencing idle problems and you did not remove the idle mixture needle valve and flush those passages and replace that little "o"ring, then you will, in all likelihood, continue to have idle issues. Refer to the parts page below and reference items 3, 6, and 19.

Yes, these carbs are a pain to get cleaned up and squared away when they get contaminated but, following the advice you've already been given regarding draining and prevention, problems are truly few and far between.

The only thing I would contradict is that you should NOT get in the habit of running this outboard on muffs. A trash can with a cutaway and filled with water as a test tank is a FAR better way to go and will give you a much more accurate idea of how your water pump is working.

Good luck.

I pulled the spark plugs as Mike suggested...can't do the drop test at this time since I already pulled the carbs. I have attached a picture of how the plugs looked in top, middle and bottom order.

Thanks for the info on the jet set. I've got everything disassembled but have not attempted to take the thin tube out yet. How do I remove it?

I have not removed the idle mixture valve either, I have not figured out how to get it out with the odd looking 180 deg. stop that is on the head of the mixture screw....I attached a picture of what mine looks like?

I'll stop by my local Honda dealer tomorrow and see what parts they have in stock....jet set (with 0-rings) and float valves.

Sorry guys but I can't get the pictures to upload for some reason. I'll keep trying.

Take one of the carbs with you. Ask them to show you the passages that the fuel takes for idle.

Mike

Refer to the aforementioned parts page (that I will, this time, upload...NOW! ) here:

http://www.boats.net/parts/search/Honda/Outboard Engine/2003/BF25A3 LRSA /CARBURETOR/parts.html

To remove the "jet set", unscrew item #12 screw, plug.

Note that these plug can be fairly stubborn and I have been forced to use an impact driver occasionally to get them to turn without "boogering" up the screwdriver slot. They are made of red brass and thus are somewhat soft. Most of the time, though, they come out with a good, square tipped screwdriver that fits the slot exactly.

With the plug out, item # 20 nozzle, main, pretty much slides right off. Make sure that you note which end is up and lay it aside.

Now, item # 19, jet set, is exposed and is just hanging there, held on only by the friction of the "oring" that seals it at the top of the carburetor throat. The easiest way to get these out is to take a small, slot, pocket screwdriver and go into the front of the Venturi (throat) tube and wedge the tip between the carb and the little lip that the oring sets on and give it a twist. The jet will pop right out.

The idle adjustment needle valve illustration doesn't show a limiter cap but it sounds as if yours has them. This is where the picture would be helpful to me as I have not worked on this specific outboard. If the limiter is a little chromed thing with a pointer that can only sweep within a cast ridge in the body of the carb, then it is like the ones I'm familiar with and I can give you directions for removing it.

I gave you the jet set info just in case the guy at the shop just pops it out and you don't get a chance to see the "sleight of hand". He won't be just "popping" out the idle screw if it has a limiter since they are a little "beastly" themselves.

Thanks for the detailed instructions on the jet set removal. I tried it and they popped right out. Two of them came out nice and snug but one came out easily....seemed too easy to have a proper seal.
I inspected each jet tube with a magnifying glass and I did not find any cracks or debris at all, even the tiny holes were clear.
The idle adjustment needle is exactly as you described. It has a little chrome limiter ear on it that only allows it to be turned 180 deg. If you can provide any help getting the idle adjustment needle out that would be great?

I went ahead and bought 3 carb o-ring "rebuild" kits so I can replace all the o-rings, especially the ones on the jet set when I go back with everything. Unfortunately the Honda mechanic was not there today so I couldn't speak with him. The counter guy said that the carbs may need to be synchronized even after all the cleaning is done.

Sorry for the delay, very busy Monday.

To remove the idle screw, you can use heat from a soldering iron to melt the glue that holds the plastic, chromed head that you see to the actual idle screw. The actual idle screw is slotted and can then be backed out counter clockwise.

These screws are designed to break off if the chromed head is tampered with and will sometimes do that even when you apply heat and are trying to be careful.

I've gotten to where I just break them and replace them with new. If you do break off the inner head, you will be presented with a smooth, flat surface that is hard to get a hold on to screw out the needle valve. I use a very sharp dental pick and use that to get a purchase on the outside edge of the smooth screw head so that I can "push" it around counter clockwise.

Now matter how you are able to turn the screw, it still, usually, does not want to just back out of the hole. This is because the oring under the head acts as a sort of lock that keeps it in the hole. You have to use a small, pocket screwdriver and the pick to work it out of there by prying and poking and holding your tongue just right. Not hard, just a pain.

The counter guy is correct. The carbs must be synchronized up to get the best idle and maximum performance. There are many synchro tool kits on the market if you want to do it yourself or you could get it running and have the shop do the work.

I was able to talk to my local Honda mechanic today and he suggested the same removal process for the chrome screw cover. He did however say that if they epa ever does an emissions check and the chrome screw covers are not on there I could be fined big bucks per carburetor! So, he suggested putting them back on after the removal and cleaning of the port.

Not sure how likely an emissions check is so I was wondering if just grinding down the little ears on the chrome screw covers with a dremel tool might be less likely to damage the screw for removal. What do you think?

I certainly replace each and every one on my rental as they do an excellent job of what they were intended to do...prevent tampering with the idle mixture.

The notion of the EPA inspecting your outboard is laughable to me. I've been waiting for the EPA refrigerant police since 1994 to show up with my $25.000 per occurrence reward money for information about HCFC releases to the atmosphere. This was after I was forced to obtain a "refrigerant certification" in order to buy the stuff. Ha ha Ha!

There have been "dummy screws" going on American made car carbs since around 1970 and I know that the majority of them have been "tampered" with. But I cannot site one instance of ANYONE, EVER, getting penalized for doing so.

Yes, go ahead and grind, spindle, fold or mutilate that cap in any manner you desire and sleep well knowing that the EPA will absolutely not be at your door the next morning.

Yep - the EPA has more important things to regulate - like claiming that ditches are public waterways which come under their control. So now, they want you to do an enviromental impact study and get five different permits before you can dig a ditch.

Good news. I got the idle mixture caps off last night by heating them with a soldering iron and gently prying them off. I found that each mixture screw was open approx. 1 1/2 to 1 3/4 turns. Does this sound about right?

Gave the carbs another good going through using a syringe with alcohol to identify the passage flows. I soaked the jet set in carb cleaner for an hour or so and I'm in the process of cleaning those small thin tubes. Good Lord those holes are small in there. I'm using a small strand of wire to push through them, then a squirt of alcohol through a syringe followed by a blow of compressed air. I'm inspecting them by holding each up to the light and looking into them with a magnifying glass, then repeating as needed. Any tips on how to give them a thorough cleaning?
Once I get the tubes clean I'm going to start re-assembly.

That is why I replace them. If they are plugged, you can not tell for sure if you have thoroughly cleaned them. The way they are constructed, the small tube is butted up against a larger tube, making a small ledge internally. Even if you can see all the way through the small hole, there can be particles lodged on the ledge, which you can not see. They can look clean, then you put everything back together, and then after you run it for a while, particles (if there) can break loose and your idle goes to hell again.

I only want to do these once. Plus, I do not like customers coming back saying...."it's doing the same thing".

The mixture screws are supposed to be 2 3/4 turns out for the 25A.

Mike

This evening I got the carbs carefully put back together and installed. Turned the key and it made a weird sound like the starter wasn't engaging or something......then I realized I forgot to put the spark plugs back in! After I installed the plugs she cranked right up, sputtered a couple of times and miraculously started to purr. I adjusted each idle mixture screw after the engine warmed up and the engine is idling better than ever. I'll give it a water test tomorrow.

I could not have done this job without the advice of you folks. Thanks very much, it feels good to have done this job myself.

Paul

Ahhhh, the old missing spark plug trick! Done it to myself.
Goodonya man, for gettin' it done. I hope you are done but, like hondadude says, those little jets have bitten us all where the sun don't shine.
You can't argue with success though and I hope your power test goes,... well,...successfully!

The water test went well today. I ran the motor about two hours at varying speeds and it has never run better since I've had it. Just a bump of the key and it would fire right up every time and idled like a Honda should. I'll keep those carbs run dry and drained so hopefully the little 25hp will run well for a long time.
Thanks again for the help and advice.

Paul

Love it! Congrats.

After replacing a couple of prop shaft seals, I now just buy the whole holder assembly when I find one leaking. For all the labor and risk of not getting the new seal in without damage or leakage, the cost is well worth it.

So, yes matthewmagness, I agree.

Question: Have you tried replacing the shift shaft seal down there? If not, be advised that if you are planning to, you will need to remove the retainer pin that Honda calls a "roller" (item #40 in the illustration link below) from the (what I call it) "shift shoe" and what Honda calls a "rod, push" (item #14) in order to remove the shift "rod B" (item #11).
http://www.boats.net/parts/search/Honda/Outboard Engine/2005/BF25D5 LRGA /WATER PUMP/parts.html

My experience has been that you need a special tool to get that pin, or roller, out cleanly as it will NOT come out with just a pin punch. I broke a few quality pin punches trying to get it to move before I finally made a "pusher" tool out of a small, high quality C clamp. Actually, I ended up making two tools. One with a short, cupped "tip" to get it started moving without slipping off the end and another, with a longer, flat, tip to push it part of the rest of the way. THEN, and only THEN was I able to use a pin punch to knock it the remainder of the way out.

But, then, that's just me. A guy with a steadier hand and good set of eyes might get it done without all that.

Hi matthewmagness,

It sounds as if you are a fairly capable mechanic. You certainly don't seem to be intimidated by this outboard at any rate. Replacing that shift shaft seal is a bear for any wrench! That being the case, I have a suggestion.

Since this forum is for sharing ways of getting maintenance done, if you opened a new thread explaining how you are going about this latest repair and put an appropriate caption like "WATER IN OIL" or the like, then others that have this problem could read and benefit from your experience. Since this thread is titled "MISSING AT IDLE", most folks are llikely skip by it looking for help and miss the valuable resource your knowledge could provide.

And, with that heading, you might get some fruitful tips from others here that have "been there, done that" that would help you as well. Either way, I'll be waiting with interest about how you are doing. Any pictures of ongoing work appreciated!

Ah, I was a farm boy meself. Couldn't wait to get away and never found a way to get back. Saving money has always been an unreachable goal of mine too. I try, I fail, I try again.

No sir, I don't have a 25. I do have a stable of 27-8hp and 15 of the 20hp twins that I am responsible for. I also freelanced a while before the economy meltdown and worked on some 9.9 versions. I also buy and sell older B models when I can find them. I used to do all the repair myself but, since I was recently disabled a bit, I now have a helper that does all the grunt work. AT LAST! I'm the "brains" of the operation.

I chimed in on yours because the lower ends are pretty much the same throughout the Honda line except for scale. Bigger HP/bigger parts. Otherwise, pretty close in design and component configuration. At least to my untrained eye.