The mower ran fine up when it was put up last fall. Now it has no spark. It is an older 3.5hp model with the non-adjustable carb that a friend was throwing out because it wouldn't start. After unhooking the kill switch it started on the first pull and has been in use for the past two years without a single hick-up....until now.

I have replaced the point and condenser (the plunger is working fine), and set the point gap to .020", cleaned the flywheel (the magnets work, at least they do on one side, I guess this is normal?) and gapped the coil to it at .014". Next I disconnected all ground wires to the coil leaving only the wire to the condenser and the plug wire. Still no spark. Is there a coil test that can be preformed if you've nothing but hand tools and an ohm meter to work with?

Not being inclined to spend much on this mower I would like to confirm with some degree of certainty that the problem has been identifyed before plunking down money for a part that can't be returned.

Thanks ahead of time for any and all help!
Scott

bad coil? try adjusting the gap some more, card trick and dollar trick

bad coil? try adjusting the gap some more, card trick and dollar trick


Is narrowing the flywheel-coil gap tighter than .014" a tuning trick? I got the spec I used from a local lawn equipment repair guy.

The air gap for a coil on a smaller engine is .006-.010", the opposite side of the flywheel has counter weights not magnets.

Coils rarely fail, check the points and make sure you are getting good contact, use a multimeter and check there should be little to no resistance between the contact points, make sure the primary lead wire from points to coil is not bare and grounding to engine block anywhere, make sure flywheel key is good.

If you decide to replace the coil, get a magnetron unit and you won't have to deal with the points anymore.

Good Luck....

Thank you!

The Kohler engine service manual shows how to test a magnatron type coil with a ohm meter. Can a briggs coil be tested in the same way?

Check ohms between grounding terminal and the armature and note ohms. Then test between grounding terminal and spark plug wire and note ohms.

What should the ohm readings be for briggs magnatron type modules?

Thanks Russ.

Set the flywheel gap to .006", ohmed the points and double checked that nothing was grounded; still no spark. Guess it's time to bite the bullet?

try another coil (if you have one)... and try different gaps continuously. is the points and condensers hooked up right