Honda BF15 no spark; ignition coil problem?

cynosure

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Jan 21, 2012
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Model year 2000 Honda BF15a 4-stroke won't start. Historically it has always started on the second pull, even after many months of no use. Problem started immediately after motor got pretty hot when it stopped passing water maybe 1/2 mile from destination. I've since removed the impeller fragments, replaced the impeller, and flushed out the water system, including removing the thermostat and running water directly into the engine as well as through the thermostat tube. (Thermostat not stuck, moves easily with moderate thumb pressure.)

Starting: Have worked through shop manual troubleshooting procedure:

-- Spark plug looks wet and smells gassy, not fouled or oily.

-- No spark visible, even in the evening, when I do the spark test, even with new plug and used but OK old plug.

-- Stop switch seems OK: no continuity when switch open (engine run position, with little spacer key in slot in red button), continuity when I remove the key and switch closes (to kill the motor).

-- Brightened up the metal tabs on the cam pulley; the little magnet they pass by seems strong, as do the flywheel magnets.

-- Got varying readings when checking the CDI (with two different multitesters) -- I don't have one of the special testers called for in the shop manual.

-- Have checked and rechecked, unplugged and reseated all the various connectors.

-- Exciter coil, pulser coil, and ignition coil secondary circuit resistance numbers all within spec per shop manual.

-- Ignition coil primary circuit a little out of spec. 0.36-0.43 ohm called for; I show 0.9-1.0. Aha. Must be the problem, right?

Measured the coil on a friend's BF15, just for grins. Older model, but same spec for ignition coil primary circuit (I checked his shop manual). His coil, which works, measures 1.0 ohm across the primaries.

What's up? Why would one coil (his) work and the other (mine) not? When the ignition coil fails, does the primary develop greater resistance, or break and show no resistance? Or does the problem lie elsewhere? If so, where? I've checked and measured everything. Would the engine's getting quite hot have contributed to the problem? Or just coincidence? What to try next?
 

hondon

Lieutenant Commander
Joined
Jun 11, 2001
Messages
1,922
Re: Honda BF15 no spark; ignition coil problem?

Look really carefully at the contacts on the sensor that operates off the cam pulley.They can get even a little rusty and fail to work.An ohms test will generally not reveal this and without a DVA meter you wo'nt know what that output is.Also look carefully at all wireing that runs around the head and of course check the valve adjustment and compression to make sure you did'nt tulip a valve.
 

cynosure

Recruit
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Jan 21, 2012
Messages
4
Re: Honda BF15 no spark; ignition coil problem?

Thanks for those tips. Maybe the excess heat from when the impeller failed but I had to run the motor for a while nonetheless caused the wiring to break or the insulation to melt and the wiring to short out somewhere. Will micro-reinspect wiring and connectors, test for continuity where possible. Will also check the other items you mention. Thx much.
 

cynosure

Recruit
Joined
Jan 21, 2012
Messages
4
Re: Honda BF15 no spark; ignition coil problem?

Tried a new ignition coil and a different CDI, individually and together. Still no spark. Oil level OK, about in the middle of the dipstick. Can find no problems in the wiring harness. Every connection re-checked and re-checked again. Pulser coil and exciter coil test to within spec. Switch appears OK: still no spark when black/red wire disconnected, also, I can get continuity/no continuity depending on whether the little ignition key is in place or removed. Cam pulley tabs not rusty, nor is the magnet on the sensor under the cam pulley. Flywheel magnets grab a screwdriver tip strongly.

Is there a hidden over-temp fuse or cut-out switch, or some other little device that could be preventing spark? The oil pressure light flickers when I pull on the starter cord, so there's electricity in there somewhere. I am completely baffled and at this point have no idea what else to try. All suggestions welcome.
 

GMRodriguez

Recruit
Joined
Jan 14, 2013
Messages
1
Re: Honda BF15 no spark; ignition coil problem?

Tried a new ignition coil and a different CDI, individually and together. Still no spark. Oil level OK, about in the middle of the dipstick. Can find no problems in the wiring harness. Every connection re-checked and re-checked again. Pulser coil and exciter coil test to within spec. Switch appears OK: still no spark when black/red wire disconnected, also, I can get continuity/no continuity depending on whether the little ignition key is in place or removed. Cam pulley tabs not rusty, nor is the magnet on the sensor under the cam pulley. Flywheel magnets grab a screwdriver tip strongly.

Is there a hidden over-temp fuse or cut-out switch, or some other little device that could be preventing spark? The oil pressure light flickers when I pull on the starter cord, so there's electricity in there somewhere. I am completely baffled and at this point have no idea what else to try. All suggestions welcome.


I'm experiencing the same problem with my Honda BF15. Where you able to determine what was causing the no spark condition?
 

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,554
Re: Honda BF15 no spark; ignition coil problem?

You do realize this was a year's old post, right? maybe better to start a new one...
 

cynosure

Recruit
Joined
Jan 21, 2012
Messages
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Re: Honda BF15 no spark; ignition coil problem?

I'm experiencing the same problem with my Honda BF15. Where you able to determine what was causing the no spark condition?

No. I just triple-checked all connections and fiddled with things and wiggled things to make sure everything was tight, seated correctly, etc., and it started. I still suspect there's something going on, though, because despite starting great most of the time once or twice it wouldn't start. Then mysteriously it would start just fine a short time later.
 
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