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Honda BF50AY "NO SPARK" problem

newboater67

Contributing Member
I have a 2000 Honda BF50AY that I'm getting no spark on any of the cylinders.<br>
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I have not ohm'ed out the CDI unit yet but the exciter coil, all 3 pulser coils and all 3 ignition coils tested in spec. The service manual says you have to remove the spark plug cover to get the correct results (2.8-3.4 Kohms for the coil and spark plug wire). <br>
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You have to remove the covers because the ones installed on my motor are Nichiwa LD10F which should measure 10K. I have one that reads 350-450 Kohms and can't find them on the internet or Honda parts diagrams.<br>
<br>
Nichiwa was bought by NGK, but I get no results found when I try searching for them on NGKs site.<br>
<br>
Does anyone know if the specs for the covers/boots for the spark plug wires have ever been changed? All the ones I find on the internet are 5K. I can only find the 10K caps overseas in euros.
 
I have a 2000 Honda BF50AY that I'm getting no spark on any of the cylinders.<br>
<br>
I have not ohm'ed out the CDI unit yet but the exciter coil, all 3 pulser coils and all 3 ignition coils tested in spec. The service manual says you have to remove the spark plug cover to get the correct results (2.8-3.4 Kohms for the coil and spark plug wire). <br>
<br>
You have to remove the covers because the ones installed on my motor are Nichiwa LD10F which should measure 10K. I have one that reads 350-450 Kohms and can't find them on the internet or Honda parts diagrams.<br>
<br>
Nichiwa was bought by NGK, but I get no results found when I try searching for them on NGKs site.<br>
<br>
Does anyone know if the specs for the covers/boots for the spark plug wires have ever been changed? All the ones I find on the internet are 5K. I can only find the 10K caps overseas in euros.
Hey.
you can't trust ohm specs .. Ohms changes .
check your lanyard switch first. And you need to find out which part is not working by
using DVA and voltage tester. 1. Cdi output 2. Trigger output 3. Charge coil output
the reason you need to use dva are. It slows down the signal and let you see the real voltage output
. It converts ac signal to dc signal.. You cant use voltage tester without dva.
 
I know the ohms checks are just a quick static check and you would have do the actual output checks with a dva meter or dmm with a dva adapter which I have. I did the ohms checks first as a quick preliminary inspection.

One of the spark plug boots is reading 30-40 times higher than the other 2 which is not good. They should definitely read 10 Kohms. One reads 8.8k, one reads 10.8k and the 3rd reads 340-440k. That increased resistance would suppress the spark to that plug.

You can't measure the output at the spark plug. It should be in the neighborhood of 15,000-20,000 volts.
 
Spark plug cap should be 7.5 to 12.5K ohm.

It is very unlikely that all of the coils failed at the same time. If all of the resistances are the same, they are probably fine.

Have you checked voltages from the exciter to the CDI? Pulsers to the CDI?

Also, make sure your safety landyard has a clip in it or disconnect the landyard altogether from the key switch.

When you have the safety landyard on and the keyswitch on, check for a ground on the black/red lead. It should be an open circuit. When the key switch is off, there should be a ground. If you have a ground all the time, you will not get spark. Probably, the easiest place to check the black/red lead would be around the key switch.

Finally, the spark on these motors is very hard to see. What kind of spark tester are you using? Do you have the spark plugs removed, so the flywheel turns fast? Is it a spark gap or a light that you put in line. (The lights typically do not work). One easy way to check, would be to put the spark plugs in the motor, connect the plug wires and put a timing light on each lead. If the timing light flashes, most likely, you have spark.

The ignition circuits on the 50's is very hardy...if you have no spark at all, it could be the exciter, pulser wiring, or cdi. It could also be possible that you lost the magnets under the flywheel. I have seen many magnets delaminate on the vintage that you have...no magnets = no spark.

One last question....you did not say if this motor is new to you or if the problem just happened, all of a sudden.

Mike
 
Mike,

I've had the motor for a year. I'm the same guy with the timing/carb issue. I went out to run the checks you posted on the timing/carb thread, and couldn't get any spark.

Am I reading the wiring diagram wrong? It looks like BL/R would send ground to the cdi as long as the safety switch is active.

Bob
 
If the key switch is off or if the landyard is pulled, there should be a ground on the black/red. That stops the spark. The landyard has to be connected and the key switch has to be on to remove the ground...allowing spark.

Mike
 
Mike,

Thanks. Had flaky contacts on the safety switch.

One of the spark plug resistor caps ohms out at 340-440 Kohms instead of 10K. I'm assuming this should be replaced before conducting the rest of the tests. Unfortunately they're not available from Honda and are only sold in Indonesia. To order the part from Honda, I'll have to order a complete ignition coil.

Can a single ignition coil/spark plug wire be replaced by itself. I thought I had read somewhere along the way that it's best to replace them all at the same time.

Thanks,
Bob
 
This should not keep you from completing your testing. I may be wrong, but I do not think that the high resistance on one coil will cause the others to not fire.

I also have not heard that all of them should be replaced at the same time. As long as they are all within or very close to the specs, it should be good to go.

These circuits are not as precise as those you work with in imaging.

Mike
 
Hi Mike,

You're right. The high resistance on the spark plug resistor cap for cylinder 2 didn't appear to make any difference. I also gapped and installed new plugs before running these tests.

Digital tach rpm bounces around 1740-1930 rpm with the boat tach reading around 1000 rpm on all 3 cylinders. Rpm will increase on it's own up to around 1400-1500 rpm according the boat tach. Digital tach was also reading around 1750 rpm when boat tach was reading 1200. I can not verify the tach is set right at this time. I was having the tach reading wrong issue, and installed a Honda/Faria tach with digital hour meter and 1K resistor assembly. I was trying to get it set up correctly and couldn't seem to get over 4000 rpm when these other issues popped up.

All values are VDC taken with a DVA adapter and Fluke 77 IV DVM.

The exciter coil output was 216 Vdc at 1000 rpm. Voltage decreases as rpm increases.

All 3 pulser coils output around 11 vdc at 1000 rpm and 14 vdc at 1200 rpm.

It was dark so I also checked spark on the wires. Removed all the plugs first. I used one of those cheap inductive neon lights, an adjustable gap test plug, set for 0.025, and an HEI test plug. I see what you mean. I definitely would not have seen anything in the daylight. The results were the same for all 3 methods. As far as I can tell by eye, the spark quality and frequency appeared to be the same from all 3 ignition coils and spark plug wires.

I removed and inspected the spark plugs. Cylinders 1 & 2 looked fine. Cylinder 3 doesn't.

Here's pics of the plugs:

Plugs 1 & 2.jpg
Plug 3.jpg
Plug 3b.jpg

Thanks Again
Bob
 
The digital tach readings in the above post are the real rpm's the boat motor was running at when the measurements were taken. I rechecked the boat tach and it was set on 3p for some odd reason. I know a Honda dealer told me it should be on the 5p setting. If I remember correctly I believe your posts concerning the tach said it should be on the 2p setting. I set it to 2p and the boat tach and digital tach were reading the same within 50 rpm.
 
Good news on having spark, now. As well as the tach readings.

Did the speed of the engine actually increase? Did it go back down on its own? Is it possible that it just warmed up? Maybe you have some carb issues on # 3 and it finally kicked in...
It is odd that the out of spec plug cap is in #2 and the potential problem is in #3.

Yes, you can measure the inputs to the coils. Just measure across the two contacts. I have used safety pins to get under the connectors and alligator clips to the pins. Since one of the contacts are going to ground, if the measurements do not all come out the same, you may want to measure between block ground and the other contact to see if there is a difference in readings.

Sounds like you are making headway.

Mike
 
Mike,

Thank You for all your help and hope you have a Happy Thanksgiving!!!

Drained and pulled the carbs. When I pulled the carbs apart, carb 3 still had a lot of gas in it, which makes me suspect the float valve & seat. Also found a lot of built up crud in the idle screw after I drilled it out. The limiter caps were already broken off and missing on carbs 1 and 3 so I had to drill them out.

Do you recommend any carb cleaners or solvents in particular? I know you have to be careful about anything plastic (floats, float valves, O-rings, etc...). What's the best thing to soak the carbs in after all the plastic or rubber items have been removed?

Thanks,
Bob

See some crud in all the seats for
 
The best thing to soak the carbs in is water (with a cleaner solution) in an ultrasonic cleaner. The solution is like what jewelers use in their ultrasonic cleaners. Many others on the forum has had success with Simple Green, Dawn Detergent, or similar non corrosive cleaners in the water.

After going through the ultrasonic cleaner, I always spray brakeclean through all of the various passages, to be sure that fuel or air will flow through the proper way....and blow all out with compressed air.
Some have used WD-40 to spray through the passages.

You should not dip the Honda carbs in harsh solvents. That may clean out the passages, but it will also harm the protective coating on the outside of the carburetors.

I have heard of some who let the carburetors sit in a solution of Seafoam. I do not have any first hand knowledge of using Seafoam in this way. I do not know if it will harm the coating.

In general, if you have removed all of the o rings, a normal carb cleaner should be ok to spray through the passages, if they are really dirty.

You should look real close at the small black plastic piece on the end of the float valves (needles). I have found a few cases, this year, where the black plastic expands and pushes out of the end of the needle. This then causes the float height to be incorrect and it closes down the fuel intake to the carburator....thus...the engine starves for fuel.

One other thing to really look at closely, is the jet set (the long skinny tube, that goes up through the center of the carburetor). Get a magnifying glass and look for small cracks along the tube or at the base where the skinny part gets fatter. The cracks can cause the idle to be erratic and can also cause your vacuum balance to be syncronized at one minute, then the balance is off the next minute.

Mike
 
I'm guessing someone has replaced a carb on this motor somewhere along the way. I have one BG31BA at carb #1, and two BG31BC carbs at carbs 2 & 3. All 3 cover screws to the slow jet emulsion tubes were damaged and I wasn't sure I'd get them out. Finally did but have to replace them all. One of the o-rings was smashed on one of the slow jet emulsion tubes. Also found some corrosion in one of the idle screw ports.

Since I have them torn down, and have to wait for parts, I've decided to go ahead and replace the jets, float valves and idle screws (no choice - had to drill them out on the BC carbs). I'm a little concerned though because the idle screw in the BA carb is longer than the screws in the two BC carbs.

The anode also has to be replaced, so I'll be opening the water jacket to check that one and pop the thermostat and verify that's working properly as well.

Unfortunately I'm in salt water, so are there any specific lubricants or grease you recommend for the control/throttle linkage, throttle plate springs, etc.

You mentioned PRI-G fuel treatment in one of your posts. Is that a product you recommend? I switched to non-ethanol REC90 gas and am currently adding Stabil Marine to it. Are you familiar with the seafoam decarb procedure that's been posted before? If so, what's your opinion about doing it?

Hoping I'll know the outcome by next weekend. Don't know when parts will deliver for sure yet.

As always, thanks for your time and advice. It's definitely been a learning experience.

Bob
 
Very observant!

Most people (probably me included) would have just pulled the carbs off and cleaned them and not noticed the difference in idle/mixture screws until putting everything back together.

A couple of things could have happened.

One could be, as you suggested...someone put a couple of new carburetors on the motor.

The other could be that this may have been one of the last motors of the Model AY series and they ran out of carburetors and just put BA carb and 16016-ZV4-D21 for the BC carbs.

It is wise to change out the jet sets. They are impossible to check to see if they are really clean, due to the two different sized tubes in the jet.

Yes, I like PRI, but Stabil Marine is also good. I see no need to change.

As for using Sea Foam for decarbonizing....it is ok.

On carburetored motors, what I like to do, is to use CRC or Evinrude Engine Tuner and spray it into the the holes in the intake manifold where you connect the carb balancing gauges. I do it with the carb balance gauges connected. As the motor is running, I disconnect one hose at a time, hold my finger over the tube until I shoot the tuner into the tube. That is the most direct method that I have found. It is much quicker that using SeaFoam in the fuel. After I do that to all the cylinders, I let it sit, then take it to the water and run the crap out of it.

Generally, after that you should change the oil and filter. You might also have to change the spark plugs. Then, when things cool down, check/adjust valve clearances.

If you want to go the "in the fuel method", I would use Yamaha Ring Free before the Sea Foam. If you have a Yamaha dealer around. I have used it many times on fuel injected engines and had amazing results....almost like bringing them back from the dead.

You have definitely found some issues....and any one or all of those issues could be causing your problem.

It sounds like, when you get it all back together, that thing should run like a smooth sewing machine.

Be sure the clean the intake manifold surface on the engine and use a new gasket. It is generally really hard to clean off. There is no sure thing as too clean to this surface. One hint....although the Honda manual says nothing about this....if you put a very thin coating of Evinrude gasket sealer http://www.amazon.com/Johnson-Evinrude-BRP-Sealing-Compound/dp/B001KYDE2G (not permatex) on both sides of the gasket, the next time you take the carbs off, cleaning will be soooooo much easier.

Mike
 
Thanks Mike,

Any chance you have a part number for the longer idle screw for the BG31BA carb? It didn't have a limiter cap on it like the other two BG31BC carbs.

Bob
 
If I decide to use the Yamaha Ring Free, should I run a tank of the shock treatment first (2 oz/gallon), then use the normal treatment of 1 oz/10 gallons? After pulling the carbs and seeing the intake valves, it could use something to reduce the carbon buildup.
 
Yamalube Ring Free is great stuff. Yes, 2oz/gallon sounds about right for decarboning. Be prepared for a lot of gunk and soot coming out of the exhaust.
 
Chawk_man,

I'm new to boating and this would be the first time I've ever tried decarbonizing anything. If I run a full tank of the shock treatment, do I actually have to run the full 20 gallons all at once? Could you describe what I should expect, where this stuff will show up, and if there any spare parts I should carrying when I do this.

Thanks, Bob
 
Sorry....I listed the part numbers that I came up with for the screw sets, but my fumbling must have erased some of the lines.

From what I can derive....

The screw set for the BG31BA is 16016-ZV7-B51
The screw set for the BG31BC is 16016-ZW4-D21

I had to back into them in a couple different years of motors. If you come up with something different, let me know.

As for the decarbonation....just use a small tank (3 gallons or less). With Ring Free, two or three 15 or 20 minute treatments will probably clean it out. Run it hard, for a short time,under load after each treatment.

Chawk may have suggestions for other methods.

On an ongoing basis, you should follow the instructions on the bottle.

Mike
 
Thanks for the part numbers Mike.

New saga in the journey. Pulled the thermostat and popped the water jacket. Good thing I did. Found a couple small pieces of the impeller in both places which surprised me since I've had good water flow from the indicator.

Now I'll have to rent a truck and pull it out of the water so I can replace the impeller. I keep it on a boat lift which makes some of the service challenging anyway. I'll go through it from head to tow now. Should run great when it's all said and done.

I've used distilled white vinegar before to soak the propeller and hardware to get them really clean. After I drop the lower unit, I was wondering if I couldn't block the water tube, and pour vinegar through the thermostat until it was full and let it soak overnight to clean the inside of the motor and than flush it with fresh water.

Is there any kind of recommended procedure used to clean out the water side of the motor?
 
You just can't win, can you?

You are brave....pulling the carburetors over water. No matter how careful i would be, I would probably drop them in the water.

The telltale indicator comes from the lower part of the motor before it goes to the thermostat, etc. Your thermostat could be stuck closed and totally clogged and you will still see a good water indication if the impeller is working.

Let's hope that those pieces are what someone before you did not get out. Once you pull the lower unit, I would flush the system from the thermostat with a garden hose and make sure there are no other particles in there.

As for the flushing....I am in fresh water so do not have the experience. Others on the forum have recommended Saltaway and running the motor in a tank or garbage can to continually circulate the mixture while the motor is running. Hopefully, they will jump in....Jimmy? Chawk? Others?

Mike
 
When checking the valves it says to use Threebond 1201 or 1215 for the head cover packing. Can only find the 1215 in Australia or UK. Can Threebond 1207B (black) or 1211 be used instead?
 
Pulling the carbs over water was the easy part. You should see what I have to do to change the oil or gear case lube and insure none of it can fall in the water. It's almost comical. Almost !!!

Bob
 
Hondabond 4. If in a pitch, you can use some permatex. As long as it is the kind that can handle the heat and is oil resistant.

You just need a little on the bends and corners.

Mike
 
Is there any difference in the 3 ignition coils?

I see each one has a different part number and I noticed the spark plug wires have the cylinder number stamped on them. The continuity tests are the same though for all 3. Can they be swapped? Just curious since it looks like the only way I can get another resistor cap that's in spec is to order an ignition coil.

Bob
 
All the coils are the same. The only difference would be the length of the wires and the numbering. If the wires reach, change them around any way that you want.

Mike
 
In regards to the blocking of the water tube and then filling and leaving system full of flushing solution is certainly possible. I did it with an old BF15 that`s cooling system was completely choked with salt residue. I used some stuff called Rydlyme at a 50/50 mix and it worked a treat.

Cheers, Matt.
 
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