Honda BF50 intermittently runs very poorly – need help diagnosing

[mcaswell]

On a trip this past weekend in our MacGregor 26x, our 2000 Honda BF50 developed an intermittent problem.<br /><br />Engine ran great for about 2 hours, cruising at about 5,000rpm. Engine started to lose power, and I assumed tank #1 (6gal DuraTank) was empty, which it appeared to be. Switched to tank #2 (6gal DuraTank), and we continued on our way. A few minutes after that, the engine began exhibiting the problem that would plague us for the rest of the shortened trip.<br /><br />We'd be cruising along, engine sounding fine, then suddenly the engine would lose power, running very roughly with a dramatic drop in rpms. This would happen whether we were at high rpms or moderate rpms. Pulling the throttle back to idle would result in the motor dying. Pushing it forward did not produce any noticeable difference in power, aside from the more "throaty" sound of the carb's valves being opened wide. After a period of time, anywhere from a few seconds to a minute or two, it would jump back to full power and run fine. This cycle repeated over and over at random intervals.<br /><br />I immediately suspected fuel contamination, since the problem seemed to coincide with switching to the 2nd tank. There did appear to be some debris in the tank, though I would have thought that this would have been caught by the canister-type filter/water separator that is installed. I drained the float bowls several times, and switched to a 3rd tank, but the problem continued. After anchoring overnight, hoping that whatever the trash was that I presumed was in the carb(s) would have settled to the bottom of the float bowl, I drained them once again, but after motoring for 10 minutes or so, the problem started happening again.<br /><br />After sailing most of the way home, we employed the motor to get us through the bridges, and the problem worsened to the point where it was barely running at all.<br /><br />Now, though I've thought all along that it was likely a fuel problem, however, I'm now having second thoughts about this. After sharing my woes with a slip neighbor, he suggested that it could be ignition related. Hearing this made me realize that the nature of this loss of power was not gradual (as in, taking a couple of seconds to go from normal power to running poorly), but rather very abrupt and sudden, like a "run crappy" switch had been flicked. Likewise, the regaining of power was similarly instantaneous.<br /><br />Running the boat at the dock (in gear, 3,000rpms) for about 10 minutes (that's all I had time for yesterday), all was well, but it probably just needs to be run longer than that for the problem to show itself.<br /><br />Any thoughts on this? Any ideas on what I should pursue first?<br /><br />--Mike

 

[DJ]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

I am leaning more toward fuel.<br /><br />However, you can look for an erratic or missing spark, when it happens, with a timing light.<br /><br />Attach the inductive timing light lead to the number one spark plug wire. When it starts to break up, see how the light reacts. Does it still have smooth pulses or erratic? IF erratic, it's an ignition problem.

 

[dwrate]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

I have a very similiar situation on my BF75. Starts like a charm, runs great mostly... once or twice every time out it will bog down very nearly die. I used to try opening the throttle but that had no effect. No I do nothing and after 45 secs or so it goes away. Needless to say it is not very comforting...<br /><br />David

 

[mcaswell]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

I made a tiny bit of progress this evening... I was able to reproduce the problem at the dock. With the boat tied up securely, I ran it in gear at about 3,500 - 4000 rpms, and after about 20 - 30 minutes, the problem started. So, this weekend I will try new fuel, plus do the timing light thing.<br /><br />Again, bear in mind that the motor runs great until the problem starts... no hint at all of any rough running, lack of high speed power, rough idle, etc. It runs perfectly. Then, all of a sudden, it runs horribly... then perfectly... then horribly, etc.<br /><br />--Mike

 

[Skinnywater]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Since the problem became worse with time. Almost to the point of quiting.<br />Then after a rest at the dock a day or two later, it runs fine.<br />Then for 20-30 minutes it runs fine then starts running bad again.<br />As if a capacitor or transistor is leaking or breaking down with use and the heat from use.<br />I'm leaning towards electrical also.<br />It doesn't make sense that you turn it off running poorly then the next day at restart everything is fine. Fuel problems rarely fix themselves better. <br />Yet weak electrical components commonly fail intermittently.<br /><br />The pulser coil and the exciter coil and the CDI unit itself is easily diagnosed with a simple DVOM (Digital Volt Ohm Meter)at all the plug in points (pin check).<br />The entire test and proceedure is very simple and clear in the Honda Marine FSM.<br />Part #61ZV300, get the suppliment also #61ZV300Y.<br />This is the Honda Marine Factory Service Manuel for your BF50. It has every nut and bolt, wire and hose, test and maintenence proceedure, you'll ever need. Everything from top to prop. <br />About $40, an inch and a half thick, excellent illustrations. You'll need to supply your own three ring binder for it.<br /><br />Good luck and keep us posted on what you find.

 

[mcaswell]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Originally posted by Skinnywater:<br />[QB] Since the problem became worse with time. Almost to the point of quiting.<br />Then after a rest at the dock a day or two later, it runs fine.<br />Then for 20-30 minutes it runs fine then starts running bad again.<br />As if a capacitor or transistor is leaking or breaking down with use and the heat from use.<br />I'm leaning towards electrical also.

Also, I should note that when I said I was able to duplicate the problem yesterday evening by running the motor under load for 20 - 30 minutes at the dock, I also had run it a little earlier for about the same amount of time without the problem occurring... the difference was that the first time, the motor's cover was off. That might be another indication that it's a heat-related electrical component failure, as I'm sure more heat builds up in there with the cover on.<br /><br />

It doesn't make sense that you turn it off running poorly then the next day at restart everything is fine. Fuel problems rarely fix themselves better.

When the problem first happened out on the water, I was thinking that it was a piece of garbage floating around in one of the carbs, which would periodically happen to block a jet, then fall free (hence my draining the float bowls thinking whatever was in there might get flushed out). I don't know enough about carb biology to know whether that scenario is likely or even possible (not to mention said trash would have had to get past the filter / water separator, and the engine's own filter).<br /><br /><br />

The pulser coil and the exciter coil and the CDI unit itself is easily diagnosed with a simple DVOM (Digital Volt Ohm Meter)at all the plug in points (pin check).

I will start troubleshooting in earnest this weekend. One method for checking for intermittent heat-related failures that I read about here while searching through old posts is to put a blow dryer on the suspected component while the motor is running, and see if the heat triggers the symptom. I'll also do the meter check.<br /><br /><br />

The entire test and proceedure is very simple and clear in the Honda Marine FSM.<br />Part #61ZV300, get the suppliment also #61ZV300Y.<br />This is the Honda Marine Factory Service Manuel for your BF50.

I have the Clymer shop manual, which I think has these test procedures. Should I get the Honda manual anyway?<br /><br />--Mike

 

[cp]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

I'd say it'd be a good idea to get the factory service manual (FSM) in addition to the Clymer manual. The FSM has much more specific info, not to mention that in my usage of the Clymer manual I've encountered several "inconsistencies" which Clymer acknowledged were errors when I asked them about it. BTW FWI I agree the symptoms point to an electrical problem for many of the reasons already stated above, and I think the heat gun troubleshooting is a good idea. The converse would be to use a cooling spray (available in most electronic stores) after the problem occurs to isolate the component by cooling it. Let us all know what you find. Good luck!

 

[mcaswell]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

I hit the CDI unit with the blow dryer yesterday evening (ran the motor at fast idle, did the blow dryer for about 10-15 minutes), and found that it did not prompt the problem to occur. From glancing at the shop manual, it appears that the other ignition components are under the flywheel... is there any way to heat these components while running the motor?<br /><br />--Mike

 

[nadderdaddy]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

hairdryer? you seriously need to think about getting your motor to a trained tech and quit trying to melt things and please dont start trying to fiddle with the carbs 1. read your owners manual-should be a little passage in there about reduction mode, this is your smart little motors way of self preservation in the event you have a problem which you do 2. you have not mentioned, IS THE THING PUMPING WATER !? -No? see item 1. 3. If your using a hair dryer then I get to ask questions like, did you open the tank vent ? when was the last time it was serviced, do you have oil? in the engine? -correct wieght and amount? how many hours of operation ? definently do not take it to the guy that told you to use the hairdryer when you take it to the tech please tell him/her everything youve done to fix it so they can repair that before they diagnose whatever is actually going on and never- ever-tell your service shop "you changed my oil and now my trailer lights dont work"

 

[mcaswell]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Originally posted by nadderdaddy:<br /> hairdryer? you seriously need to think about getting your motor to a trained tech and quit trying to melt things and please dont start trying to fiddle with the carbs 1. read your owners manual-should be a little passage in there about reduction mode, this is your smart little motors way of self preservation in the event you have a problem which you do 2. you have not mentioned, IS THE THING PUMPING WATER !? -No? see item 1. 3. If your using a hair dryer then I get to ask questions like, did you open the tank vent ? when was the last time it was serviced, do you have oil? in the engine? -correct wieght and amount? how many hours of operation ? definently do not take it to the guy that told you to use the hairdryer when you take it to the tech please tell him/her everything youve done to fix it so they can repair that before they diagnose whatever is actually going on and never- ever-tell your service shop "you changed my oil and now my trailer lights dont work"

Yes, I was aware of the RPM-limiting mode... I don't think this is it though, as it runs very poorly when the problem occurs, and goes from running well to running poorly very abruptly (I think I recall reading in the manual that the speed limiting function of the motor would result in a gradual drop in RPMs).<br /><br />The tell-tale water stream is present, and the motor does have the correct amount of oil.<br /><br />The tank vent is the very first thing I checked, and I also tried switching to a different tank.<br /><br />The motor has about 130 hours, and it's been about 7 months since it's been serviced.<br /><br />A local tech did not tell me to using a blow dryer / heat gun. I came cross some old posts here that suggested it (as a way of making a heat-related intermittent failure show itself). I doubt it gets hot enough to melt anything.<br /><br />--Mike

 

[Skinnywater]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

mcaswell's original post:<br />

We'd be cruising along, engine sounding fine, then suddenly the engine would lose power, running very roughly with a dramatic drop in rpms. This would happen whether we were at high rpms or moderate rpms. Pulling the throttle back to idle would result in the motor dying. Pushing it forward did not produce any noticeable difference in power, aside from the more "throaty" sound of the carb's valves being opened wide. After a period of time, anywhere from a few seconds to a minute or two, it would jump back to full power and run fine. This cycle repeated over and over at random intervals.

This isn't indicative of the presevation mode.<br />Plus the red indicator is synomonous with an overheat. (Page 90 of the owners manuel)<br /><br />Get the motor to start running poorly again.<br />Then run the pin check of the components that are in your manuel.<br /><br />

when you take it to the tech please tell him/her everything youve done to fix it so they can repair that before they diagnose whatever is actually going on and never- ever-tell your service shop "you changed my oil and now my trailer lights dont work"

If you do have to take it in for repairs. Don't take it to a shop that is rude, condescending, and have lost respect for the customer.<br /><br />Please keep us posted.

 

[mcaswell]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Originally posted by Skinnywater:<br />Get the motor to start running poorly again.<br />Then run the pin check of the components that are in your manuel.

I plan on doing this tomorrow, weather permitting. Can I ask you a HUGE favor? Could you give me the testing procedure for the CDI? The Clymer manual essentially says "the way to troubleshoot the CDI is by process of elimination... if you have an ignition problem, and all the other components test OK, it's probably the CDI." I'd prefer to actually test the CDI if possible.<br /><br />One other thing... I do not think the problem is related to just one cylinder. Running the motor in the slip today, I pulled one of the plug wires to observe how the motor sounded and behaved. When the problem occurred out on the water last week, it was significantly WORSE than what I saw today after pulling the plug wire. So, that leads me to believe that it's not something specific to one cylinder (whether it be some sort of fuel blockage, or an ignition problem), but rather something that is affecting all 3.<br /><br />

when you take it to the tech please tell him/her everything youve done to fix it so they can repair that before they diagnose whatever is actually going on and never- ever-tell your service shop "you changed my oil and now my trailer lights dont work"

If you do have to take it in for repairs. Don't take it to a shop that is rude, condescending, and have lost respect for the customer.

The previous owner of this boat had purchased an extended warranty, which I believe has another year or so left on it. So, I have no intention of repairing it myself. However, I desperately want to avoid a situation of repeatedly having the repair tech run it at the dock at fast idle for a few minutes, then giving the boat back to me and saying nothing's wrong with it. I really want to try and determine what the problem is (or at least have some clue) BEFORE I bring it to them.<br /><br />I know the owner of my local shop pretty well, and I stressed this concern to her today when I stopped by... she seemed to understand. Perhaps I can simply take the mechanic for a ride out on the lake so he can witness the problem firsthand (it's somewhat difficult to get it to happen at the dock... running the boat in gear at 4,000rpms for 20 - 30 minutes tied up is not my idea of a good time!).<br /><br />I'll continue to troubleshoot this week, and bring it to them next Saturday (their mechanic is on vacation this week, so no sense in bringing it now anyway).<br /><br />--Mike

 

[Skinnywater]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Send me your email and I'll scan off the page and send it to you.<br /><br />BTW, on todays ignition systems, pulling off plug wires without grounding them, can damage the systems components.<br /><br />bachelor@stormnet.com

 

[mcaswell]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Originally posted by Skinnywater:<br />Send me your email and I'll scan off the page and send it to you.

Will do. Thanks!<br /><br />

BTW, on todays ignition systems, pulling off plug wires without grounding them, can damage the systems components.

Eeek! Well, I'll be sure not to do that anymore.<br /><br />I took the boat out this afternoon to try and get an ohms test on some of the suspect components while the motor was in its misbehaving state. This turned out to be trickier than expected, as the problem was being "more intermittent" than before. It had been run for about 30 minutes at no-wake speed, then about 30 minutes at around 4000 - 5000 rpms making runs up and down the bayou before the problem started happening, but the poor-running state was fairly short (5-10 seconds). During one of these times, when the situation permitted me being at the mercy of the wind, I shut the motor down, quickly pulled off the cover, and checked the pulser coils and the ignition charge coil. Both read a little high (compared to what the book says, and compared to how they read earlier at the dock with the motor cold), but I think this is normal.<br /><br />Of course, the problem here is that after plugging things back in, the motor started right up. So, even though it was malfunctioning at the time that I stopped the motor, there's no way of really knowing if it was still in its "failed state" at the time I actually took the readings, as obviously sometime in between, whatever component that was causing the problem started working properly again.<br /><br />It was getting a little late, and satisfied that I had done all I could, I began slowly motoring back home. Hoping to avoid the sheer joy of losing the motor in a semi-crowded marina, I left the motor's cover off (hoping it would help keep it cool), and kept my speed to a minimum. Of course, the problem happened again 10 minutes later at a very inopportune time, and because the throttle was near idle, the motor died. In this particular part of the bayou, the bank was lined with concrete rip-rap, which the wind was blowing me towards. Ouch. Fortunately, I got the motor started again, and in gear, which is not necessarily easy... if the motor is in its malfunctioning state when its started (with some throttle applied, in neutral of course) I cannot get it into gear, as the motor dies when I pull it back to idle to try and get it in gear.<br /><br />I continued, though I ran at a bit of a faster speed since that would help ensure the motor would remain running if the dreaded problem happened again (which it did, several times). Nearing the marina, I had to slow down, though I kept my hand on the throttle, and had to increase it several times to keep it running when the problem happened. I made it into the slip safely.<br /><br />I then ran the motor for a few more minutes in the slip, until the problem happened again, and once again took resistance readings on the components I had tested earlier, and had similar results.<br /><br />With today's experience, I'm fairly certain the problem is not related specifically to one cylinder... as I mentioned in an above post, the motor ran much better with one of the plug caps removed than it did when the problem was happening out on the water. With this one cylinder intentionally disabled (which, again, I won't do anymore!), the motor would still idle, and still responded to throttle increases... in its malfunctioning state, it would die near idle, and no matter where the throttle was, it would not go past about 2,100 rpms.<br /><br />So, it's looking more and more like the problem must be a weak and/or erratic spark that affects all cylinders, which seems to implicate the CDI and ignition charging coil as possible culprits (anything else to consider?).<br /><br />This at least gives me some info to pass along to the mechanic next weekend. It takes me about an hour or so (by water) to get to the shop from my home slip, so I'm sure by the time I arrive there, the problem will be in full bloom, or almost ready to be... perhaps I can convince him to come for a quick ride with me to witness it firsthand.<br /><br />--Mike

 

[radsrh]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

My 2 cents worth, if it is under warranty stop playing with it and take it in. You are going to take off a hand, blow the motor up, or run your boat aground messing with it. A warranty is just for this and if you keep pulling plug wires and heating things up your shop could just as easy say that you caused the problem and not cover it.<br /><br />Shop time $35.00 hour<br /><br />if you worked on it first $70.00 hr<br /><br />if you watch us work on it $140.00 hr

 

[mcaswell]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Originally posted by radsrh:<br /> My 2 cents worth, if it is under warranty stop playing with it and take it in. You are going to take off a hand, blow the motor up, or run your boat aground messing with it. A warranty is just for this and if you keep pulling plug wires and heating things up your shop could just as easy say that you caused the problem and not cover it.<br /><br />Shop time $35.00 hour<br /><br />if you worked on it first $70.00 hr<br /><br />if you watch us work on it $140.00 hr

Yeah, I'm pretty much done at this point, and will leave it alone until Saturday when I try bring it to them. My efforts were not necessarily geared towards fixing the problem, but rather a desperate attempt to identify it. As I've mentioned before, because a considerable amount of patience is required to make the problem rear its ugly head (running at moderate to high speed for at least a half hour or so) and is not easily reproducible at the dock, I'm concerned about getting caught in the cycle of "we cleaned the carbs, and that should take care of it... good luck," only to have the problem persist, and have to bring it back again and again.<br /><br />I guess this fear stems from an experience we had with a brake job done at Firestone. Shortly after, my wife noticed a loud squealing noise emanating from the front wheels after she drive for 10 or 15 minutes... it was loud enough so that people on the sidewalks would turn and stare as she drove past. We brought it back to this shop 3 or 4 times, describing the problem in detail, and repeatedly mentioning that it needs to be driven for 15 minutes before it starts happening. Each time, they called us with a cheerful "your car is ready," and that there was no noise. On the way home, the noise would start again. Finally, out of a fit of frustration, I demanded that one of the mechanics come for a ride with me. Less than 10 minutes into the drive, the noise started, and as before, it was impossible not to notice. But get this... even after this, they STILL didn't fix it.<br /><br />Furious at this point, I took the car to a small, dirty, ugly shop near my work, and they quickly identified the problem as cheap brake pads, easily remedied by using OEM pads. That was the last time I've taken any of our cars to Firestone.<br /><br />So, anyway, my concern is that the Honda tech will run the motor at fast idle for 20 minutes or so, and pronounce the problem fixed (or say it never existed in the first place).<br /><br />Hopefully, he'll prove these fears unfounded, but I think I will try to arrange a demonstration ride Saturday... because the motor will be plenty warm by the time I get there, the problem should be easily reproduced. Or perhaps we can tie it up securely in a slip and get it to happen there.<br /><br />--Mike

 

[BillP]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Hey Mike,<br />I have a mariner 50 4 stroke that gave me intermitent problems of stopping. The problem surfaced after the motor ran for a few minutes too. I located the problem at the harness connector mounted on the engine. The connector pins were hollow and not spread large enough to make perfect contact. I spread them out for a tighter fit and the problem went away...that was in 1997 and the motor hasn't missed a beat since.

 

[mcaswell]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Here's an update on my motor...<br /><br />I took the boat to the Honda dealer (by water, not on the trailer) yesterday. My hope was that by the time I got there, the motor would be hot enough to be misbehaving, but that didn't happen. The trip there consisted of about 5 minutes at idle speed, around 30 minutes at high speed, then another 15 minutes at slow speed. When I arrived, I was pleased to learn that the mechanic was going to go out in the boat right then, so that he could observe the problem firsthand and do some diagnosing too. I thought this was a good idea, since the motor was already well warmed up, and it shouldn't have taken too long for the problem to occur.<br /><br />It took much longer than I thought... about another 40 minutes... for it to happen, though it was coming back to life too quickly for him to find out anything, though I did immediately conclude that it was definitely not a fuel problem, and that it was electrical.<br /><br />Slowly motoring through no-wake zones, it started happening again, and he was able to do some of the things he wanted to do. First of all, he pulled the #1 plug cap, which caused the motor to die. After we were back up and running, he waited for it to act up again, then pulled the #2, then the #3 wires, which didn't produce any noticeable difference in performance. So, he reached the conclusion that when the problem happens, only the #1 cylinder is firing.<br /><br />So, he believes it is the CDI unit, and will probably replace it to see if that clears up the problem.<br /><br />--Mike

 

[Skinnywater]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

Thanks for the update. I hope the replacement will end the problem.<br />Please keep us updated. <br />Assistance and efforts given here are kinda paid back with final outcomes.

 

[mcaswell]

Re: Honda BF50 intermittently runs very poorly – need help diagnosing

The problem appears to be solved. After they replaced the CDI (finally), I ran the boat for a couple of hours today with no trouble (the past 3 times I took the boat out, the problem happened within 30 - 60 minutes). So, apparently it was a faulty CDI, causing #2 and #3 cylinders to lose spark. <br /><br />I'll do an extended sea trial (3 - 4 hours) this weekend.<br /><br />Thanks for the help!<br /><br />--Mike