Logo
FULL SITE MENU

BF 50 Struggling at Idle

N

neversummer

Regular Contributor
2007 BF50 carb model. Approx 50-70 hours.

I started her up for the first time this season today and she started right up but is struggling / dying at idle and is shaking more than is typical.

Backstory --- last summer I had a water in the gas issue (seawater, rainwater, probably some of both) that caused the same issue. The Honda mechanic replaced one of the carbs, which didnt solve the problem, so I went back and he removed and thoroughly cleaned all three carbs. This solved the problem and I happily used the boat for the last month or two of summer. When I put it to bed last fall, all was well running-wise and I winterized carefully (stabilized fuel, drained carbs, changed filters, etc etc).

Now it appears to be struggling at idle again---after a while (on the muffs) it will struggle and die. I drained all the carbs, drained both inline and Racor filter, and put some seafoam in them. This temporarily solved the issue but I let it run for about 45 minutes and the problem is coming back (probably because the seafoam is burning off). Interestingly, the problem mostly goes away if I fast idle, but even at 2,000 + rpms it sounds like its skipping a bit.

Any idea whats going on? Its a fuel / carb issue, correct? I REALLY dont want to go back to the mechanic especially since it would be weeks to get in the door and I already blew through $1k last summer on this issue in parts and labor.

Thanks in advance for anything you've got!

Ted
 
A few more details to add:
- The gas I used is fresh (bought today)
- I tried the cylinder drop test --- pulling the plug boots one by one (each time, the motor struggled further and recovered after replacing the boot -- this suggests to me that its not a single cylinder issue)
- I checked the plugs (new last fall) and they look pretty dark but not damaged or anything (I assume the darkness is from the seafoam---replacing the plugs with old ones from a prior year didnt seem to help).
-The motor sounds WORSE if I pump the primer bulb
 
If it sounds worse when you operate the manual fuel pump it would lead me to believe that there is an issue with the carburetors.-------Remove intake " muffler " and operate the manual pump. --See if you can spot one of the carburetors leaking / overflowing.
 
racerone said:
If it sounds worse when you operate the manual fuel pump it would lead me to believe that there is an issue with the carburetors.-------Remove intake " muffler " and operate the manual pump. --See if you can spot one of the carburetors leaking / overflowing.
Click to expand...

Thanks Racer -- on my engine the carbs on clearly visible on the starboard side -- but should i remove the plastic intake screen forward of them anyway? Im quite sure they are not leaking.

Im also assuming this is a carb issue, but seems very strange since they were all stripped down, dunked 3 times, and cleaned by the Honda mechanic last year and then it wasnt an issue again until now. I dont know how the jets could have gotten contaminated again because I was very strict about giving them clean fuel for the rest of the season and put them to bed fully drained - so im wondering if it could be another issue (carb sync, fuel mix, etc)
 
I ended up taking my motor to another Honda dealer, who was very polite and took the time to hear about my issue. He said he would do the diagnosis for free and would not charge me if we could not find out exactly what was wrong. I will keep you all posted.
 
Sorry to not have jumped in sooner...

Sounds like you chose the right dealer.

I do not really have any magic answers. There are a couple of things that are common to all of the cylinders..

1. Timing...may have jumped timing...but squeezing the fuel bulb should not cause any change.

2. #1 (top carburetor) may be faulty, or the starting circuit in the #1 carb could be malfunctioning (maybe a stuck float, blockage in the carb bowl or bystarter stuck open)

3. (yeah, I know, I said a couple)....could be carb balance is out....but again...why squeezing bulb causes a change..who knows?

I am sure they will check all the basics like compression, spark, timing, etc

Mike
 
Thanks Hondadude. My money is on 1) blockage in carb #3 related to the water in the gas episode I had last summer (a particle worked its way out) --- 2) carbs out of balance.

I may have overstated the effect of the primer bulb -- I mostly noticed it did not improve anything to pump it. It may be totally unrelated.

A few more things I did notice that may help our investigation: 1) after letting it struggle at idle on the muffs, I noticed that the 3rd cylinder (bottom) was not as hot as the other 2 -- I could only put my finger on the head next to the spark plugs for the top 2 carbs for about two seconds before it really hurt --- not as hot on the bottom carb.

2) After taking off the intake cover and looking at the carb throats, I noticed that at idle and revving, the valve in the throat of the 3rd carb was not opening as wide at the top two (the top two were opening the same amount) -- does this suggest a sync issue?

I will certainly share how this turns out
 
Well after my outboard has been at the dealer for 1 month, the service manager is telling me "its still running poorly". I dont understand. He pulled off all the carbs and cleaned them and said they were clean. He claims he sync'd them. I dont get it -- the motor might have 60 hours on it maximum. I told him I would come pick it up.

One thing I noticed was that the bottom cylinder is not as warm as the top two cylinders when running and if I pull off the intake cover, I can see that the butterfly valve on the bottom carb does not open as far as the other two --- does that suggest a sync issue?

Please help, I am at my wits end with frustration.
 
What does running poorly mean?

The bottom cylinder will probably be cooler since it is the first to get water to it.

What all did the dealer do? Check....compression....spark.....timing......fuel.....idle mixture settings.......double check hose routing on/between carbs.........valve clearances?? Does any one cylinder have a problem or does it not matter?

The bottom carb butterfly being at a different angle does not suggest anything specific to me, unless it is extremely different.

Mike
 
As always, thanks for your response Hondadude.

The engine will start on the first crank and idle well for a few seconds, and then as time goes on (30 seconds) the idle gets worse and the engine stuggles to stay idling, shakes, and then dies. The dealer claims to have cleaned the carbs and synced them, but I am not sure of this -- I never got any calls back about what could be wrong with it and finally just picked the boat up (I wasnt charged for it)--so needless to say im very frustrated.

I will ask the new dealer (tomorrow) about compression, spark, timing, fuel, mix, etc. In the few seconds of good idle I got today on the muffs, I tried a cylinder drop test and found that the idle and shaking worsened after each boot was pulled (suggests to me that its not a single cylinder). Unfortunately I dont trust myself enough to tear down the carbs myself and I dont have the specialty tools to see if the carbs are in sync, so I will have to try one more dealer. Thanks again.
 
Check the timing marks before anything else. If it jumped timing by one tooth, it will idle like it has a bad carburetor.

Make sure the new dealer knows that they have to clamp off the hoses going between the carbs to sync it.

As I think about it, your cylinder drop test was probably not valid, just after start up. All of the cylinders were probably running off of the enrichment of the fuel coming from the starting enrichment circuit. The idle circuits may still still not be clean or sync is really way out.

The dealer just has to go through all the basics to eliminate the major mechanical and electrical issues.

Mike
 
OK so amazingly (fingers crossed -- being very cautious not to jinx myself) the engine has "fixed itself". Ran it at home (basically wouldnt idle) then brought to the mechanic 1 hour away. He ran it and called me and said it idled normally with no issue!

His guess is that the trailering from home to his shop caused whatever was stuck in the carb to come loose -- or released the float bowl. Either way its idling normally now.

Amazing.
 
Wow! A self healing machine. It is patent time!

The good news is....it is running good now. The bad news is....you do not know why...and will always wonder when it will fail again.

I hope you have continued...smooth running.

Mike
 
Thanks -- I've had it running for about 2 hours since, mix of idling and WOT --- no issues so far, running very smoothly.

I've clearly learned my lesson and I dont care if im over doing it precaution-wise because its worth it --- from now on always fresh stabilized gas, a little seafoam every tank or two, and I will physically drain each carb if I am leaving the boat for more than 2 weeks.
 
Just an update on this.

I ran the rest of the season with no problems at all, at least another 20 hours. The engine purrs at idle and is strong all the way up through WOT. I genuinely believe that something tiny was stuck in a carb jet and worked its way out with all the bumps in the road when I was trailering to the ramp---works for me!
 
Well, I completely missed this one until now (we have some severe illness in the family so maybe that's why) but I'm glad you had a good outcome.

I don't like the bottom throttle plate being at a different angle than the other two but...if it ain't broke, don't go tryin' to fix it! Just enjoy the boat as long as you can until the next little problem jumps up!
 
Sorry to hear about your family health troubles -- Ive been there myself all too recently -- hope all is improving.

Yea, Im still not sure why that bottom throttle plate was like that (at idle), but as you say, cant mess with perfect.

On my last trip out I was 7 miles out off the coast of Maine -- seas were like glass and I hit my fastest speed at WOT, 33 MPH on GPS -- cant knock it if it works!
 
My idle problem is back. NOoo!

Here is a video. Still runs like a top at high RPM, its just at idle it shakes and sputters.

I dont understand. Everything in the fuel system is clean. I am religious about clean brand new fuel. Carbs have been professionally cleaned several times. Yesterday morning the bottom carb was not responding to the cylinder drop test, so I worked up the courage to learn how to pull the bottom carb. It was pretty spotless, only thing I couldnt get to was the mixture screw (I broke Hondas limiter cap, and the screw head with it.) After the cleaning, all 3 cylinders were firing fine, but it still misses and struggles at idle as you can see in the video. If i lowered it to 950 RPM, I think it might sputter and die at idle.

Per HondaDude's comments on other threads and this one, it sounds like my next options are:

1. Figure out how to check timing
2. Buy some sync gauges to be sure the carbs are synced

 
Honda 50 06. 1 cylinder not working spark going to plug makes no difference when u disconnect plug lead dried changing Koils but the problem shifted to a cylinder i had not touched answers would be thankful .
 
Mr. Walsh,

Because our issues are separate, Id appreciate if you'd start a new thread for your engine.

Thanks.


Eamonwalsh70 said:
Honda 50 06. 1 cylinder not working spark going to plug makes no difference when u disconnect plug lead dried changing Koils but the problem shifted to a cylinder i had not touched answers would be thankful .
Click to expand...
 
Hi neversummer...I sent you a question with my phone but I guess it didn't get posted.
Anyway, when this was happening before, you said that it starts and idles smooth for 30 or so seconds and then starts to chuggle like it's doing. Is that still true this time?

Also, you said at one point that you had broken off the idle mixture limiter cap and, as a result, the head of the mixture screw as well. Has that been repaired or did you just leave it?

It sounds as if the idle is "lean". Also, if it is starting nicely and then faltering after a short time, that would also indicate that it 'likes" the enriched condition the bystarter (auto choke) is providing and then "dislikes" it when the bystarter begins to lean out the mix. You can test this by unplugging the bystarter electrical connector at the top carburetor. This will leave the bystarter in the "full rich" or "full choke" position. Do this when the engine is dead cold and then see if it "likes" to run smooth quite a bit longer than it does now.

But, as the engine warms, this mixture should be too rich and the engine should start "loading up" and begin faltering. Shut it off and allow it to cool before plugging the bystarter back in and restarting the engine. This will keep the engine from "flooding out" and causing a hard start condition. If you can video this little "homemade" test so that we can see it, we may come up with some decent direction to point you in.
 
Hi Eamonwalsh70
Welcome to the forum. You will get more and better responses if you start your own thread. Please take the time to make it as clear as possible. Punctuation and the use of the spell check feature provided here will enhance the group's ability to understand and try and help you solve your problem. There is NO penalty for typing more than one paragraph.
Thank you.
Eamonwalsh70 said:
Honda 50 06. 1 cylinder not working spark going to plug makes no difference when u disconnect plug lead dried changing Koils but the problem shifted to a cylinder i had not touched answers would be thankful .
Click to expand...
 
We have had 6 BF50's and put maybe 4000 - 5000hrs on them in total. Only time we had an idle problem (on a ~1600hr engine) the mechanic adjusted the idle screws by ear and it was perfect again after that.
Could your problem be that the auto enrichment is sticking on? i.e way too much fuel at idle once the engine warms up. At higher rpm's the auto enrichment wouldn't be so noticeable due to the increased air flow. Can't tell you to test this unfortunately as never had that problem.
 
Thanks all.

Jgmo to your question, yes for the first 30 seconds or so things are good, but that may be because the RPMS race up to 1800 or so for the first few seconds. As it starts to warm up, the RPMs settle down to 1000 and then the shaking starts, perhaps 30 seconds in.

I won't be near the boat for a few weeks, but I will try your bystarter disconnect suggestion when I can.

I sheared off the idle screw on the bottom carb just 2 days ago when I had the bottom carb off and was trying to access that passage. It is not repairable, so if any adjustment is needed, I will need to replace that carb. Perhaps replacement is needed anyway, because every once and I while I will do a cylinder drop test (if shaking is occurring) and the bottom carb wont be firing (again, and intermittant issue, most of the time it reacts to the test just like the others).

Thank you!
 
You can get that idle screw out. It just takes a couple of dental picks stuck in to the flat surface of the screw that you can see and then "manipulated" in a counter clockwise direction. New screw kit will come with screw, oring and new limiter cap. It needs to be done so that you can check for proper carb sync.

Well, with it idling that high during enrichment, I don't know if my little test will be productive or not. But it won't hurt to give it a try and see how it acts.

The more I watched your video above, I just get the feeling that the carbs are not in sync. They all responded when you pulled the plug wire so the ignition system is firing. So, it is going to be a fuel delivery problem of some sort.....I THINK! I would love to see what a set of sync gauges would reveal.

But, the intermittent "fixes itself and comes back" deal and the way you thought you "shook something loose" while trailering makes me wonder if it might be something like sticky piston rings. A stuck ring would "shake loose" and it might also come out of the groove enough to re-seal against the cylinder wall under certain conditions. I'm thinking that you may want to try a product like Yamalube Ring Free and give her a "shock treatment" if you haven't already.

Hitting it with the new Sea Foam spray and "fogging" it is another decarbonizing technique.

It may be time too to take a look at the valve train and make sure everything is adjusted right. I don't think tight valves would cause this particular symptom but checking them and keeping them adjusted is always good practice and you just never know. Look for everything being as it should while you are under the valve cover.

The main thing is to NOT GIVE UP! You will find it if you keep hunting!
 
Thanks Jgmo. I think you are on to something with the carb synchronization. Are you able to recommend carb syncing gauges? Possibly this?

http://www.amazon.com/Motion-Pro-08...p/B000K7JHWA/ref=cm_cr_pr_product_top?ie=UTF8

Seems like a pretty straightforward process, once they are connected.

Because the origin of my problem was after some seawater got in the gas, I think you also may be onto something with the stuck piston ring. I am also going to try some fogging oil into each cylinder to see if it frees anything up.

best,

Ted
 
That looks like a pretty nice tool! It would probably work great. To be honest, I don't even own one. I don't work on the bigger outboards so I don't need one. But, up until a couple of years ago I had a Triumph Trident. A three cylinder 750cc motorcycle that I could sync the big Mikuni's it had by using a single Snap On vacuum gauge. The trick is to get them all the SAME. If I were going to buy a carb sync tool though, I would definitely look into getting that Motion Pro.

Just be advised that some engines are synced with all the carbs hooked up to the sync tool and engine vacuum simultaneously and some engines require that you "valve off" the carburetors not being adjusted from the tool so that the vacuum reading remains stable. Your service manual should indicate which way to do that. My Trumpet was a "valve off" engine (as I think most three cylinder engines are) and that's why I was able to do it with only one gauge.

Good luck with the fogging. I hope something good happens.
 
Back
Top