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BF 9.9 not running reliably

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dvgibson

Member
I was on here last season trying to find a solution for the problems I am having my low-hours 2002 Honda BF9.9. I had it serviced after the boat was hauled but we lost 90% of the sailing season. The mechanic found the idle riser tube was plugged. We got launched yesterday, and after about a half hour of running it started failing again, and I ended up being towed back to the mooring again.

Situation: Rhodes *******n sail boat, engine in a well, This is the third engine we have had since we purchased the boat in 1992. The first was a Mercury 6 HP, pull start. We upgraded to a used Yamaha 9.9 electric start, mainly to get battery charging. It was old when we bought it and in 2002 it died. Replaced it with the Honda, because I believed everything I hear about how good it was. Not any more, It is not trustworthy. Our boat is heavy, has a full keel and the mooring field is crowed and there is a strong tidal current. No way am I going to sail through that.

When we first got the engine it was very difficult to start, took many tries each time. It turns out this was only if we had not been to the boat for a couple of weeks. It would not choke itself. After a battle, Honda replaced the stupid electric choke carburetor which cured that problem. (How great is that? No battery, no pull start. Get it?). The next problem was corrosion on the carb which kinked up the accelerator cable. Corrective action was to make sure all the spray from the p-tube got out of the hull. (Could this be the beginning of the current problem?)

Symptoms: Starts ok, then seems to idle for a bit, then starts stumbling, sometimes you can accelerate, others, no. It can be running nicely as a moderate speed, then drops way down, shudders and stumbles, and then returns to normal operation, or it may just die. Then it will refuse to idle, meaning you can not shift gears.

Yes, it is in a well. A very well ventilated well.

Gas tanks were stored clean and dry over the winter. Engine was winterized.

New gas one week ago with Marine Stable added.

New gas filter in-line since the one on the engine is impossible to reach.

Bulb pumps up fine, holds pressure, and does not affect the the problem when it is having a bad spell.

It ran fine for the first half hour yesterday, from the launch area to the mooring. Then after rigging was complete and I was ready for a spin I started it up and dropped the mooring. Just after that, it did a single hiccup. Oh,.... I grabbed the dingy off the mooring, just in case, and decided to stay in the harbor. Over the next 15 minutes it got worse and worse, would be running fine, suddenly drop way down, run rough, gunning it didn't seem to clear it up, pumping the primer bulb was no help. Hatch open on the well, but it is very well ventilated anyway. Almost made it back to the mooring but it stopped again and would not start right away and wind and tide pushed me back to a shoal area so anchored and called for help. The dingy is too tiny to steer the full keel hull. It will go the way the tide tells it.

If clean gas and two filters cannot protect this engine, then this engine has no business being used in a marine environment. I do not think it is ignition, does not behave that way. Am I wrong? Maybe the carb is corroded inside? and needs replacing again? Working on the engine means pulling it from the boat and that takes a hoist. And with the boat on a mooring that means transport to the dock and back. All very expensive and time consuming. What am I going to do?
 
Again? (I know, if it didn't get clean enough the first time, it needs to be done again until it does.) I don't suppose there is any way to get it off the engine while it is in the water, is there? Safely.
 
Hi, I'm not trying to make you angrier than you already are but I will defend the Honda "outboard" as one of the best. Especially the post 2000 small displacement motors. It does appear though that it may not be a good "inboard" or "well" selection based on your experience.

The intermittent nature of your problems sure suggest that you may be experiencing some fuel tank vent problems. I would go all the way through the procedure for verifying good fuel delivery before condemning the carburetor. Can you try a new or different hose and bulb assembly? Run the engine with the fuel tank cap loose to ensure good vent? Empty the tank and closely inspect the interior for debris and rust? Make sure the disconnects at the tank and the engine are properly engaged. The quick fuel hose disconnect latch at the engine can wear out from vibration and not allow good flow. Thus the bulb will still be hard but the engine starves for fuel. Try a piece of clear hose and look for bubbles to see if there might be air being sucked in.

Yes, it may need a carb cleaning and there are some tricks (secrets I can reveal) to getting these carbs PROPERLY cleaned and reliable. Sadly, I think many techs out there are not well trained and able to service these carburetors as well as they should. If all the steps aren't performed, you can spend a whole summer taking them off and tearing them down and putting them back on only to start over. Don't ask me how I know this...I just do.

These carbs are a bit fussy about contaminated fuel and usually need some TLC and a couple of parts replaced if exposed to water of any consequence. If yours has an accelerator pump, it is about time to work on it. I would not try to work on the motor over the water.

As far as getting it out of the well, I feel your pain. What a pain! But, I've replaced a few diesels in sailboats out here on the left coast using the boom, halyard and a come-along. You may have a "reach" problem to overcome but if you have a topping lift, you may be able to fashion an extension spar to overcome that. I know, you'd rather be sailing....me too! Know this; if it starts pretty easily and idles ok then you've got a good engine, you just need to work out the kinks.

Some questions I have are; Is the motor placed high enough in the well to keep from being swamped by following waves or wakes? I believe it should be a short shaft if it's in a well. Is it? Does it conform to your previous installations or is it longer? What's the growth situation like where you are and is it crusted up?

Getting sleepy, all for now. Don't give up!
 
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Thank you for your very considerate reply. I appreicate the thought you put into it. I am back at my "day job" now so can't reply just yet, but I will soon. I want to go sailing!!!
 
I want to love my Honda. I always wanted to get one, reliable, quiet, efficient. Maybe I will get the chance. Love it, that is.

I think it is not a fuel tank venting issue, or fuel supply up to the engine itself. The thing misbehaves at any throttle position, idle to moderately fast. Gas tanks were clean, fairly new line, new in-line glass fuel filter. All looks good. And I can disconnect the gas tank and let it run on what is in the carb and there is no change. Either runs fine, or misbehaves. It can go for about a minute, maybe more just on what is in the bowl.

I have a suspicion that it may be corrosion in the carb, since after running fine after the cleaning (professional) last fall it suddenly reverted back to the bad behavior. It did have some external corrosion problems a couple of years ago, from splash back in the well from the p-tube. So maybe something is sticking? The baffling thing is that nothing I do affects it. I think I have hit on it, then a few minutes later that does not work again.

Is there a place online that I can look at pictures of the carb? Should I buy one of the service manual advertised here? Will that help me?

Having an engine in a well is a pain, thank you for appreciating that. So many people seem to think "Just pick it up, its not that heavy." However I think the engine is happy there. Lots of air circulation. A sloped transom protects the engine from following seas. Marine growth is a big pain, but I am trying a new bottom paint solution this year for outboard/outdrives. And right now it is clean, only in the water a few days.

I have in the past used an a-frame on the stern, braced to the back stay, and blocks and other gear and the wenches to lift the engine up. I am now thinking about doing that again, and hopefully be able to work on the engine in the cockpit. It will be cramped, but to bring the boat to the dock and back to mooring, twice will be a big pain too. I wish there was a mechanic with a dock around here I could have it towed to, but the only one I know of is way too busy to get to it until the season is over.

I'm headed out there now to see what I can come up with.
 
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Update from tests run yesterday. The engine will run about 3 1/2 minutes on fuel in the carburetor, fuel line disconnected. It still demonstrates the same behavior, runs a bit just fine, begins to stumble and slows way down for maybe 10 or 15 seconds, then recovers. I can increase the throttle to keep it from stalling, but that does not affect the problem. It recovers when it wants to. I made two short videos of it which explain it better perhaps. I will post a link to them here. Is this carburetor? Or could it be something else in the engine? Air or ignition? What else is left?

http://www.youtube.com/watch?v=jDmm8dgKsN4 About 35 seconds long.

http://www.youtube.com/watch?v=36yxIL7asHE Longer, and the problem does not begin until 1:05.
 
Well, The video is so "noisy" with what I think is just echo from the motor well that it sounds as if the valves are out of adjustment. But, diagnosing an engine from hundreds of miles away is always a bit "iffy" so it is probably just the echo that makes it sound so bad. Other than that, it seems to run normally in the beginning of both vids. Is it just a pull start? Does it usually fire right up? Does it have a manual choke or is it "automatic"?

One sure fire (we'll revisit that term shortly) way to verify, absolutely, that it is being starved for fuel would be to artificially enrichen the fuel mixture with propane as the engine begins the dying sequence.

A simple propane torch would do the trick. I keep an RV size bottle on my service truck with a long flexible hose to feed propane to engines for troubleshooting. You might be able to just hold the torch nozzle (un-lit of course!) up to the intake on the sound "muffler" of the carb and give it a whiff when it starts to die. Using propane is a preferred and accepted method for diagnosing and using for a starting aid on gasoline engines and will not harm the engine as the highly volatile ether (sometimes called starting fluid) does. Never use ether if you can avoid it.

Ok, Back to "sure fire". As you may or may not know, propane vapor can be heavier than air and will tend to settle and collect in a closed space. You should be very cautious if you decide to use this technique to avoid any build up of propane in that well. I would do it in a New York minute but many folks will not be comfortable. This method is still MUCH safer than using ether or spraying gasoline into the intake.

Just a short snort of propane gas by cracking the valve open 1/4 to 1/2 turn and then immediately closed should give you the information you're seeking. If the motor picks right up and responds positively to the gas, then it is starving for fuel. If the motor continues to die or dies even more quickly, then it could be that the motor is flooding and that would also point to a sticky float in your carb.

You never asnwered my question about how long the the shaft on this motor is and if it is properly sized for this installation. If the shaft is too long, it can adversely effect the way the exhaust exits the engine due to backpressure and can cause runability issues.

Another question I have is; does this carburetor have a little rubber boot or "bellows" on the side you can see? If so, this is the accelerator pump rod and that boot should not be torn. They did an upgrade on the boot because the originals tore too easily and allowed water and condensation to enter the carburetor.
 
Re: Could it be the electric choke?

Thanks for the reply. Sorry about the video quality. I had just a dinky pocket camera with me, when I realized that it has a mic and I could do a video. Yes, there is a lot of sounds bouncing around, but you can tell how it runs, the chokes down for 10 seconds or so the comes back to life.

Which makes me think, could it be the choke? The problem happens at any throttle position, so it not just idle jets. It goes away as quickly as it arrives. Is the choke turning on when it shouldn't be? Is there anyway to test it? Or disable it?

I can try the propane test, I understand the precautions, but I am thinking now it has fuel, but is getting starved for air.

To answer your other questions.

It is electric start. It starts right up. Within a second or two. Electric choke which was not functioning right when we first got the engine. Took for ever to get it started if it had not been started for several weeks. Carburetor was replaced by Honda, under warranty. and that problem went away.

It is the standard, or "L" shaft. Probably should have been a short shaft, since the transom in the well is low. So that puts the anti-cavitation plate about 10 inches down, instead of the recommended 4 inches. The Yamaha I had before was very low profile, and I had to raise the transom for it. The Honda sticks up and I had to set the transom back down and raise the hatch cover. But sometimes when it gets bouncy we need it to keep the prop down in the water. But I would think that would be a performance problem, not an intermittent.

I will have to look for the rubber boot. I ordered a manual, which should help me locate things in the engine.

I am preparing to pull it with a A-frame and then put it on a stand in the cock pit. I would love to have a mechanic with experience look at it, but the harbormaster and all his buddies just laughed when asked what they though of my chances to get either of the two good local mechanics to take a look. "Go sit out in front of their homes. They never return phone calls in the busy season." So I am an engineer and I have done carburetors over many years, (more than 40, but just out of necessity) but this is the most modern one I have had to deal with. Maybe I should get the online manual too?
 
I deal with quite a few of those electric chokes. In the four or five years I've been around them, I've never had a problem with one. I have a new one just in case but have only used it once and then put the used one back because that was not the problem. It could be in your case but I'm betting it isn't. That's how I test them. There is a procedure for testing them but you have to remove the carb to get the damn thing out anyway. It is basically a heater coil that warms a bi-metal and moves a pin when the engine starts charging. You apply 12 volts and wait for 1.5 minutes and the pin should extend. Although, I've measured over 40 volts DC on that harness at higher than idle RPM. Bottom line is that if she starts right up and idles fast (pin retracted, enrichment passage open) and then idles down in about a minute, it's working.

I wouldn't bother with any repair manual except the HELM PUBLICATION HONDA SHOP MANUAL for your engine. Worth the extra money when compared to the others ie: Seloc or Haynes. Even so, they don't really tell you how to clean the carb reliably but I can walk you through that.

I guess that if the motor worked ok on the boat for a while, then it being a bit long legged shouldn't be a problem now.

These carbs are a bit finicky but simple enough. The secret is that if the carb has an accelerator pump and if that circuit is plugged in the least, the engine just wont run right. It's as if the carb needs that "boost" passage open so that it can breathe properly. When it comes down to it, I don't think that they are very effective accelerator pumps because the engine will stumble pretty badly if the throttle is opened too fast even when the pump is brand new. Usually only a problem on the tiller models though as you can really twist the throttle hard. Anyway, sounds as if you are going through with it and I intend to stick with you and get you out the other side. Let me know what happens next.

If you haven't already, try to drain some fuel from the carb bowl into a glass to see if any water is at the bottom of the bowl. If there is, you don't need to bother with the enrichment test. Just pull the motor and pull the carb. One thing I run into with the plastic "muffler" is that it will break when you try to remove the bolts. Spray some PB-Blaster rust buster on the bolts as far in advance of removal as possible. This MIGHT keep the brass encapsulated nut from breaking out of the plastic housing. Bad design, plain and simple.
 
Well, I have some good news, sorta. Miracles do happen. I got my mechanic to go out to the mooring with me this morning and we ran some tests. To get it start acting up it needs some load, so we tried to drag the mooring. Sure enough, in a few minutes it started acting up. He says, "You are loosing a cylinder." He checked everything he could, but too much is under the lower covers so we decided to pull the engine. He got a boat to take us to the dock and manhandled it out of the well himself. Its off to his shop now. I will keep everyone posted.

I have a question: "How does that ignition coil work?" I see on the diagram that its one coil, with two leads that connect to each spark plug. Where is the distributor? How is that done. My mechanic says there are two magnets on the flywheel, one for each. But I only see only one wire going to the CDI.
 
You know, that's a good question. I believe the term is "waste spark" for a strategy used to fire many simple, two cylinder engines. Meaning that the coil is firing both cylinder's spark plugs simutaneously but when they are in different positions.

It works because the cylinder that is fuel charged and ready to fire (piston moving up and both valves closed for compression) is out of phase with the cylinder that is not firing but is completeing the downward stroke on the power cycle or the intake cycle depending on cam timing.

The gas in the cylinder on intake doesn't ignite due to the narrow (14.7:1 stoichiometric) air fuel ratio ignition band for gasoline and lack of compressive heat for total vaporization to achieve that mixture.

I am really sorry I missed that a cyliner was dropping out when I looked at your video. It did cross my mind that it could be happening but with all the noise in the video, I was looking for excessive shaking for that and didn't really detect it. Seems like it IS much better for a mechanic to be "on the scene". And, in my defense, I am always amazed at how smooth these things do run on just one cylinder.

Yeah, makes perfect sense that you are losing a cylinder.

Look at the ends of the spark plug wires and see if they look rusty inside. If they will unscrew from the coil, look in the wire "towers" (otherwise known as the wire receptacle) and look for discoloration especially the rusty look. If you think the coil is at fault in any way, replace it. I've had them OHM out good but replaced them and solved my problem. If that doesn't fix it then it will probably be in the CDI/ECM unit and that can get complicated as the testing procedure is sort of unrealistic. They are a bit pricey though for just a "test". Hopefully your mechanic can get you fixed up ok.

I am fortunate to have a fleet of motors to work on and just swap out a known good one when I have an ignition module that is suspect. Sometimes it is just a poor connection. I've taken a "known good one" off of a good running engine and swapped it and the poor running engine perks right up.

Then, being "thoroughly thorough" I try the "bad" module on the previously "good' running engine to verify that it is scrap and, lo and behold, BOTH engines run perfectly! The Lord and electricity work in mysterious ways! Both engines go out and make money (rentals) day in and day out and I can only chalk it up to bad connections.

Having an extra good coil on board is not necessarily a bad thing. I hope you fully get the thing straightened out before she goes back in the well.
 
I know I should be working and not thinking about this but I don't see how it could be just one cylinder, unless it is one spark plug shorting. The two spark plugs are in series with the coil so if one goes, the other does too. Unless it shorts. OR, new idea, one of the magnets on the fly wheel is moving around and not triggering a spark for one cylinder. OR neither of them is getting a decent spark when it is stumbling.

Now that the mechanic as seen it happen on the water, and had to lift it out of the well himself, I think he will test thoroughly in his test tank. He wants it to run, and does not want a call back. In fact that is why he rejected putting it on a stand in the cockpit to test it. No way to prove the problem is resolved till it is back in the water.
 
I promised I would post the results here. How emabarissing. It was a defective plug! Less than 30 hours on it, looked perfect when both the mechanic and I pulled them out to check. I did not change them simply because I did not have any out on the boat. Sure enough, when it gets a bit warm it starts failing under load. You can get it started again, but then a few minutes later it starts failing again. Motor is back on the boat now and we have done some serious motoring, and serious sailing. And last Sunday another boater even complements us on how quiet our engine was coming through the mooring field!

And jgmo, yes you are right. They are in parallel. Thank you for catching me on that.
 
thanks 4 the update. Good news! The thing I like being correct about is that you really DO own a great little outboard!

Now, your next assignment is to find a good technique for draining that carb to keep her running tip top. Let's go sailing!
 
I know this is an old thread but I think I have the definitive answer to this problem and I hope it might help others that are still experiencing issues.

I had exactly the same symptoms and to cut a long story short it is because the CDI is breaking down. Thats the cigarette packet sized black box on the top of the engine. If you tap the box (or even give it a squeeze) when you get the symptoms it will often cure the problem for a while.

I was ripping my hair out (not that I have much) for weeks trying to sort carbs and wigghly amps out and then one day when it was running rough I leant over the engine and leant on the box for support and the engine began to purr like a kitten...

Bad news is they are expensive.... About £220 in the UK, so I imported one from the states for about £120 all in.

Hope this helps

Tony
 
Boy, I thought I had come back here to post the final resolution but I don't see it now. Something very similar to the CDI you mention. It was one almost brand new spark plug that failed under load. And that cost me a season and $700! Ran great for the 2011 season!
 
Hi dvgibson

Well, your problem would also cause the same symptoms I suppose. The CDI was causing the sparkplugs to fire at the wrong time. Definately not plugs for me though... I went throught 6 of them.... And several sensors......And a replacement carb.... And a replacement ignition unit.... I was ordering spare parts from ebay like they were going out of fashion!!

I have researched it a bit since I sorted the problem.. I found an old boy who is a wizzard on Honda's (Wish I had found him earlier!!).. He chuckled to himself when he heard of my woes and then gave me another gem of advice.... He swears by wrapping a couple of strong elastic bands round the CDI.. Seems to sort the problem... I just bought a ne one though..

It's a learning curve eh?

Cheers
Tony
 
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