JD L120 Rider with B&S V-twin NO SPARK

Discussion in 'Mechanic and Repair' started by tmanley, Jun 22, 2005.

  1. tmanley

    tmanley LawnSite Member
    Messages: 1

    Hello all.

    I have a John Deere L120 Garden Tractor with a 18hp or 22hp (Cant rememeber) Briggs and Stratton V-Twin engine that has no spark on EITHER plug.

    I have replaced the plugs and tested safetly switched (besides..if a switch was out..it wont even allow starter to crank)

    Okay...I dont get a spark on EITHER plug so Im kinda thinking it may NOT be the Magneto armetures/coils and has to be something else. I would THINK it would be rare for BOTH the coils to go at once.

    What else should I check?

    I notice there is a wire from the wire harness going to each Magneto/coil and for giggles I put a test light on these connections while cranking over and I get not power-should I ?? Im presuming that these should supply power to the coils and when the magnet on the flywheel passes by each coil thats what tell the coil to send the spark to the plug. Does this seem right?

    Someone said the check for a diode between the two coils or inline with the coil wires but I dont see one.

    Im presuming I have no points or condensor? I dont see them anywhere. Not familiar with this new style engine. Im also presuming the wires that go Under the flywheel are for the alternator cuz they pass through the voltage regulator...

    what the heck could it be? or most likely is it the coils and BOTH are shot??
    Thanks for your help. I appreciate the time out of your guys busy days?

    Sorry as to Im not familiar with this new style engine...anything else I ever work on has a distict coil and condensor.

    Its a 2003 Deere.


  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    The two wires you talk of on each coil are the kill wires, This is a eletronic ignition engine,The coils have a pulse coil built inside that tells them when to spark as the magnet rotates past each one. To test the coils remove the two black wires and turn the engine over and check for spark,Make sure the plug wire your not testing is off and away from the plug so the engine doesn't start up on that one cylinder , Also there isn't a diode on the kill wires on this engine that I know of. I don't believe you have a coil problem,If you have spark with the wires off trace them back on the mower and make sure their not shorted to ground.If not go back through the safety switches.
    On some units I've seen they will turn over but wont start unless someone is in the seat (seat switch kills the ignition).

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