How To Replace Magneto / Coil and Diagnose Spark Problems on Small Engines



Video on how to remove and replace magneto / coil / armature on small engines, this is very similar on any small engine, but I’m using a 11 horse model 252707 B&S as example. And talk about how to diagnose spark problems on small engines. Thanks for Watching!!!

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38 thoughts on “How To Replace Magneto / Coil and Diagnose Spark Problems on Small Engines

  1. My bench set up fixture had Briggs flywheel magnet mounted on spinning wooden flywheel by 12v fan motor. + DC speed controller. The pre 1982 type (new) ignition coil did not spark with various adjustments. This was with the removable Briggs brand trigger module. I even tried 5 universal Nova trigger modules with the same old style (new) armature with no spark. I tested with ohmmeter for grounds each location as ok. New spark plug was tested ok by ohms. After watching your (sparking video), I took it all apart and filed all ground surfaces with miniature flat file. The new Briggs ignition coil that also had factory varnish now fires the spark plug. I will now attempt the changeover again for the universal trigger. They don't require the spinning magnet to effect ignition as they use the rising voltage in primary to fire the internal transistor. These older points type coils would spark at a lower RPM range than the now modern Magnetron types. I was worried that the motor wasn't spinning fast enough, and I had no RPM test gauge. The rust was causing a poor ground, even though surfaces and screws actually look good by eye. Thanks for the good video.

  2. Should there always be a wire going to the coil? Working on a Homelite leaf blower and don’t see any wires going to the tab, the coil is just bolted down

  3. I got a craftsman riding lawn mover with a Briggs and Stratton engine 15.5go and the problem that I have is that the engine only sparks one time when is cold and then I turn the engine off and when I try to turning on one more time it doesn't turn on I check for spark and no spark in the spark plug and the I let it cool down for the next day and starts but only the first time I try second one and the same problem do you have any Idea what it may be because I change the magneto and still the same problem with a band new magneto please if you have any Idea let me know Please reply thank and very good video have a good day thanks.

  4. man i could use your help. I have a troy bilt zero turn with a twin cylinder Kohler courage that i converted to remote control. It's been working fine firing up everything has been fine. well, today im cutting grass with it and i shut it off for 15 seconds tops and when i try to fire it back up i get nothing. Im getting no spark from either coil. Im getting around 8.9 kilohm resistance on both coils but neither is working. i removed the kill switch from coil to make sure that wasn't the problem im getting no spark at all. It just seems weird that both would go out. do you have any idea? ill donate some money to ya if you can help with this.

  5. Great video. Very helpful and well done. Thanks a mill. Have a generator that couldn't start… replaced the coil after trying all else and worked like a charm, but two weeks later after a few half hour runnings I now have the same problem. Hoping it's exactly what you described. If not maybe the new coil went bad, but I doubt it. Do you have any vids on how to check the coil itself? Thanks again.

  6. What are all of the symptoms of an ignition coil problem? I have a walk behind mower that will not start 9 times out of 10 but if I spray carb cleaner into the intake from the carb with fuel in the tank the engine will start and keep running. If I release the engine control lever for a split second the engine will shut off and not restart. Is this an ignition coil problem?

  7. Guitar man I pulled the valve cover yesterday I have the exhaust valve is set at 10 the other I cant even get a 2 mm in there do I need to file it down to 6 I haven't pulled head yet 78 year 31/2 briggs

  8. Guitar man I'm having trouble I done away with points 3.5 briggs put different coil on tapped the coil cleaned base where coil sits new plug everything I can think of no spark whst is going on

  9. Just a data point from a 7.25 HP/ 190 cc Briggs and Stratton mower I was de-bugging for hour s on end! I had to replace the auto-choke plastic linkage as mice had eaten one end of it and the bugger still wouldn't start. Coil resistance was 6.3K ohms through and about .3 ohms from kill wire and metal stack housing. Spark tester showed that the plug was firing as the light went blinkey-blinkey when it was pulled. Cleaned that carb up nine ways to sunday too! Took it to my buddy, Super Mario. He through in another older plug that was cleaner and viola! It started right up. We cleaned up the orginal spark plug and gapped it correctly. DID NOT REALIZE this would cause such a hard to spot problem, especially when the spark tester showed some activity. Those things probably do better testing the coil than the quality of the spark. Lesson learned, clean or replace the spark plug to eliminate an easy problem!

  10. That's when you use a harmonic balancer puller and run it down till it has pressure on it then hit the bolt that's pushing on the crank with a hammer pop loose every time.

  11. I have a 9.9 HP Chrysler Outboard I am having an issue with. One spark plug sparks real strong and hot and the other is real weak. The coil packs have been tested and are fine. What other main suspects I should check?

  12. I'm working on an old(1970) Kohler K91 motor with no spark. Hoping to get thru it without having to buy any expensive parts. I knew about(but forgot about) sanding those contact areas under the coil. Imma go pull the flywheel and coil and check that. Glad I watched your video before putting it all back together for another day.
    On that motor, the magnets are on the inside of the flywheel. Is there any way of setting a gap between the coil and magnets on the flywheel, or is it fixed?

  13. I have a Sears st/12 Tecumseh motor replaced the coil hard to gap it behind the flywheel, I have spark now possibly not enough to start it, how do you gap it? it's getting gas why else would it not be starting?

  14. I'm going wild here,but I'd say the author is NOT from New York or New Jersey


    ……Don't matter,everybody here is too rich to bother with fixing crap,so there's plenty of Curb Side Sales (free)

  15. Good video, thanks. I am working on an engine with no spark. I bought a new coil on ebay which comes from China. When I ground the shut off tab I feel the pulse of electricity. There is no connection from spark plug wire to ground–zero ohms-open. Is this a defective coil?

  16. I have gcv 160 honda on my log splitter the motor runs great till it gets warmed up then it starts sputtering till it eventually shuts off after cool down it's fine I am pretty sure it's not fuel I'm leaning towards coil is getting hot I ordered a new coil is there something I'm missing any insight would be appreciated

  17. Hi Tom -Good vid  -I have a problem with A 17.5 less than a year old Briggs . No points just mag system. Coil shorted out (burned out) I replaced it with a new one, and that one burned out after third start up . Both coils would not fire with the kill wire disconnected when  I tested them. Could the problem be in the kill wire shorted ? please help Thanks

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