Honda bf50 spark and carb issues

[Newbie sailor]

This is crossposted and hoping to get a little more help.

I was handed down a sailboat with the BF50 sitting for around 5-7 years. Upon first start up, new non ethanol fuel, hose hooked up. Motor ran but started leaking from carb 1 dust cap. Other forums pointed me to a stuck float. Didn’t run it after that.
Took the carbs apart, cleaned in sea foam, checked float and needle float in a sink of water, they looked good and floated, no cracks. I reinstalled carbs with new gaskets and O-rings.
I started her up, still leaks from Carb 1 dust cap. But while in there I ran it a little longer and noticed cylinder 1 was not firing (I put new plugs in). Cylinder 2 and 3 had burnt fuel on them. The kicker: while running I can unplug spark plug wires 1 and 2 and motor runs with no difference. Unplug 3 motor dies.
This tells me the motor is running on cylinder number 3.
So the stage I’m at now. I’ve taken apart the leaking carb and currently recleaning it and checking float.
Questions:
Does carb 1 not firing have anything to to do with it leaking?
I’ll be posting a picture of the coil which looks to be burned.
Advice and help?

 

[Newbie sailor]

 

[Newbie sailor]

I measured the ohm between these two wires which are connected to the primary coil. Reads 0.5 ohms

 

[Newbie sailor]

I measured the ohm between these two wires which are connected to the primary coil. Reads 0.5 ohms

Books says I should get 2.0 ohms

 

[Newbie sailor]

 

[ahicks]

I can tell you that cylinder 1 not firing WILL NOT have anything to do with cyl # 2 leaking.

From there I need to know what year motor you have? Is it an '05 or older, or '06-'07?

Burnt coil doesn't look good, but I can tell you that problems like that are pretty unusual. I have to wonder what caused that. Could be a shorted rectifier (located on front, below starter). I'm pretty sure the 2 wire leads in your second pic go to both of those coils. If so, that's going to affect your resistance readings.

 

[MattFL]

You're chasing 2 problems (malfunctioning carburetor, unknown spark quality), try to eliminate one. Take the spark plugs out, put them in the plug caps, ground them to the frame while someone turns the key for you. Do you see sparks on all 3 plugs? If yes then it's probably OK enough to at least idle. If no then fix the spark problem before moving on.

For the carbs; soaking in sea foam is not worth your time. Those carbs have lots of very small holes that are easily clogged up. Disassemble the carbs and shoot carburetor cleaner through every hole followed by compressed air (wear goggles, some spray back at you). If you have an ultrasonic cleaner, soak them in there nice a hot for a while before your manual cleaning. Depending on the year, you might have a handful of tiny holes in the carburetor throat just above the butterfly valves. Shooting cleaner into one of the holes at the front of the carburetor will come out those holes which is one way to get them clean. Make sure the float moves freely and check the float needle and the needle seat to make sure they are not corroded or dirty. If you have the EPA fuel screws that only allow a little bit of turn, break the tops off, extract them and install replacements. You will now be able to shoot cleaner through those holes, plus you can get the motor to idle significantly better without the EPA limitations in the way. There's a thread around here somewhere with pictures and a HowTo from me when I did it on my 99' Honda 50. The part number I used was 16016-ZV3-000, double check if this also fits your motor.

If the carburetors are out of sync enough, some cylinders won't be firing at idle. Opening the throttle a little would get them all firing, if this was the problem. If you're careful you can sync them "good enough" to get it running by eye, then fine tune it by ear. A carburetor sync tool would be best, but you'll need to get it running first.

 

[Newbie sailor]

I can tell you that cylinder 1 not firing WILL NOT have anything to do with cyl # 2 leaking.

From there I need to know what year motor you have? Is it an '05 or older, or '06-'07?

Burnt coil doesn't look good, but I can tell you that problems like that are pretty unusual. I have to wonder what caused that. Could be a shorted rectifier (located on front, below starter). I'm pretty sure the 2 wire leads in your second pic go to both of those coils. If so, that's going to affect your resistance readings.

Cylinder 1 is not firing (or it’s very weak) it’s also the same cylinder with the leaking carb (carb 1 leaks and cylinder 1 does not fire). Sorry if there was confusion from my first post Regarding that.

It’s a 2006

Well that’s not good. So if the rectifier is bad, do you know how to test that?

I tested the coils by putting the two leads from my meter to each plug that leads to the coils. I am aware the two coils are joined together at the wires, do I need to test them separately? If so how?

thanks for helping.

 

[Newbie sailor]

You're chasing 2 problems (malfunctioning carburetor, unknown spark quality), try to eliminate one. Take the spark plugs out, put them in the plug caps, ground them to the frame while someone turns the key for you. Do you see sparks on all 3 plugs? If yes then it's probably OK enough to at least idle. If no then fix the spark problem before moving on.

For the carbs; soaking in sea foam is not worth your time. Those carbs have lots of very small holes that are easily clogged up. Disassemble the carbs and shoot carburetor cleaner through every hole followed by compressed air (wear goggles, some spray back at you). If you have an ultrasonic cleaner, soak them in there nice a hot for a while before your manual cleaning. Depending on the year, you might have a handful of tiny holes in the carburetor throat just above the butterfly valves. Shooting cleaner into one of the holes at the front of the carburetor will come out those holes which is one way to get them clean. Make sure the float moves freely and check the float needle and the needle seat to make sure they are not corroded or dirty. If you have the EPA fuel screws that only allow a little bit of turn, break the tops off, extract them and install replacements. You will now be able to shoot cleaner through those holes, plus you can get the motor to idle significantly better without the EPA limitations in the way. There's a thread around here somewhere with pictures and a HowTo from me when I did it on my 99' Honda 50. The part number I used was 16016-ZV3-000, double check if this also fits your motor.

If the carburetors are out of sync enough, some cylinders won't be firing at idle. Opening the throttle a little would get them all firing, if this was the problem. If you're careful you can sync them "good enough" to get it running by eye, then fine tune it by ear. A carburetor sync tool would be best, but you'll need to get it running first.

it’s a 2006

Alright at the moment I have Carb 1 (leaking carb) off currently and recleaning. I know I didn’t state this first but I did do all the sea foam treatment, as well as disassembling all carbs, spraying carb cleaning in all the holes and blew out with compressor as well as putting it all back together with new gaskets and O-rings. I’m triple checking the float and float needle.

Spark issue:
(Note: I have been able to start, run, and idle when the boat first came to me and it still runs and idles but obviously it runs like crap)
There are new spark plugs in it. From my last test the engine turns on and idles just very rough and weak and ready to die. WHILE IDLING, First thing I did Is unplugged spark plug wire number 1, no change in how it ran. Plugged it back in and then removed spark plug wire number 2, slight change in how it ran. Then went and removed spark plug wire number 3 and motor dies.

next I removed spark plug number 1 and tested it against the block with a friend turning the engine over. I could not see a spark but it was faint enough to ignite some of the gas vapor coming out of cylinder 1 from the spark plug port.
Did the same for number 2. I could barley see spark.
And for 3 I have spark.
Spark plug 1 looked brand new when removed.
Spark plug 2 has the faint burnt brown
Same with plug 3, faint burnt


from what I can tell. Spark plugs 1 and 2 don’t do much at idle. Rev it up and spark 1 still doesn’t do anything but 2 now has some ignition.

I do not have an ultrasonic cleaner.
I’m not sure if I have an EPA screw either.
And I have a new carb sync tool on the way. I also bought used charge coils and they are also on the way.

thanks for the reply and much appreciated help

 

[Newbie sailor]

I also want to note that the trim sensor lever was broken so that has been removed and unplugged. Not sure is that plays any roll.

 

[Newbie sailor]

 

[Newbie sailor]

 

[MattFL]

If cyl 1 and 2 have noticeably weaker spark than cyl 3 then that sounds like a good place to start. It takes higher voltage to jump the spark inside a cylinder under a lot of pressure (compression stroke) so a spark that looks weak outside the cylinder may very well be too weak to spark inside the cylinder. There is a spark gap test tool if you can get your hands on one, that will give you some way to quantify how weak the spark is. Or you can measure the parts and take a guess at which ones are bad.

Amazon.com : spark gap tester

 

[ahicks]

First, good news and bad news. Bad is I doubt seriously you're looking at an '06 set of carbs. Good news is that's a good thing! The '06 and 7 carbs are a plumber's nightmare that use an automatic choke. A complete PIA when not working right. The carbs with manual choke used up through '05 or so (like the ones in the pic) are MUCH easier to work on!

If the '06 idea is from a sticker on the rear of the cowl that has to do with meeting '06 emission standards, that was accomplished several years earlier, and that sticker is Honda's way of bragging about that fact. It has NOTHING to do with what year it is. Matt's '99 motor probably came with that same sticker! Common mistake...

My bet is that coil is toast, but if you want to prove it, I would separate them and compare resistance readings. My bet is they're way different. They should not be hard to locate on ebay. Quite a few guys piecing out motors there. Look up the part number and do a search on that.

That coil is part of the charging system. It does not have anything to do with your spark issue. Not directly anyway. For the most part, you can think of that coil as part of a different issue.

Rectifiers turn AC into DC using a couple of diodes. Try googling diode bridge or rectifier to learn more about them. Once understood they're actually pretty simple.

The #1 not firing is very likely due to the flooding you mention. Checking to see if the floats float might work in some cases, but I find weighing them on a gram scale MUCH more effective. Here, looking for a reason for the flooding, you would want to compare the float weights to see if there is one or 2 that stand out. If there's a heavy one, it should be replaced.

Float height is important as well. When installed, the float should rest with the top of it parallel with the carb body when held upside down. Check carefully for one of the 2 arms to be cracked/broken while you're at it. That's what's going to happen when trying to adjust the float level if you aren't VERY careful. Should be easy to figure out how I know that.....

Once you get that leaking issue fixed, if #1 still seems weak, a couple of ideas. The rubber o-rings on the idle mixture adjustment screw, and that tiny one at the top of the brass tube are critical to the idle mixture. If cracked or old, they will allow a vacuum leak that will just about kill the fuel draw to the idle fuel system in the top of the carb.

The #1 reason for a cylinder to not fire on idle is a clogged pilot jet. This jet is located inside (out of sight) of the brass tube located near the middle of the carb. That tube uses fuel run through it to supply the idle circuits located in the top of the carb. If you look really carefully, you should be able to see through that tube.

Another possible issue is created when somebody that isn't familiar with the purpose of the spring loaded screws in the carb linkage starts messing with them. Those control the carb sync. Properly adjusted, they make sure that all 3 carbs/cylinders are pulling the same amount of air, and are contributing to exactly 1/3 the amount of power required for the engine to idle. For example, if 2 of the carbs/cylinders are doing all the work on idle, that third cylinder (#1?) isn't doing a damn thing but going along for the ride. If you pull the plug wire, there will be no change in rpm.....

Best of luck! -Al

 

[MattFL]

The sticker in question, on my 99' :

 

[ahicks]

Thanks Matt. A picture is worth a thousand words!

 

[Newbie sailor]

Awesome thank you guys! Ill be posting next week with some feedback after using the advice given (have a welding job to tackle in Texas). I like forum posts that finish and resolve the issue for others.

oh and yes that’s the sticker that got me! I haven’t got the title yet so went by that sticker for the year

 

[Newbie sailor]

Some good news. The charge coils were bad. They were replaced with some used ones, and now have spark to all three cylinders. Not sure how they got burnt up in the first place but if the problem happens again I’ll go ahead and check the voltage regulator.
And now to the carbs:
I recleaned the carbs. Instead of buying parts and seeing if the issue WAS with floats I went ahead and swapped floats with carb 1 and 2 to see if the problem float would follow the next carb. After the swap and coil change it started up and no leaks out of the dust cap vents. So a reclean seemed to have solved the problem.

I bought a new carb sync tool and when that comes in I’ll sync them and get it running smooth.

one issue that seems to be going right now is that no water comes out of the exhaust after letting it warm up. I’m guessing the thermostat may not be working or clogged with salt and not opening or I have clogged passage ways. That’s what’s next!

 

[Newbie sailor]

Broke a bolt in in the block when trying to remove the thermostat housing. Ahhh! Lol. Oh well not my first time. Even tried to be gentle!! Had an impact drill set to the lowest setting. Just didn’t wanna come out till breaking

 

[MattFL]

Impact is not good for corroded bolts, especially small ones. I'm admittedly not the best with corroded bolts, but get some heat on it to free it up. Watch some youtube videos to get some tips. Just for reference, there should be some water coming out the exhaust all the time, though more after the thermostat opens.