Stihl blower (BR420C) with no spark

Discussion in 'Lawn Mowing' started by winecountrybum, May 13, 2004.

  1. winecountrybum

    winecountrybum LawnSite Member
    Messages: 3

    I have owned my Stihl 420C for 1.5 years and it has worked flawlessly...until now. Tried to start it as usual (1 pull with choke on & half throttle, then 2 pulls no choke) but it this time it never kicked over and I could smell that it was flooded. Pulled the plug and it appears that I am not getting any spark.

    Checked for continuity through the on/off switch in the handle. No broken wires going to the magneto. So I figured the magneto was bad, bought a new one, installed it and yet I have the same problem of no spark to the plug.

    Anybody have an idea of what I should look for next?
  2. GeeVee

    GeeVee LawnSite Senior Member
    Messages: 421

    Was the plug good?
  3. winecountrybum

    winecountrybum LawnSite Member
    Messages: 3

    Yes, I changed the plug at the very beginning, but no difference. I don't even get a spark when I disconnect the plug wire and hold it near the plug and crank it over.
  4. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    Right underneath of the carb there should be a wire connector. This connector connects the thumb (on/off) switch to the engine. Pull the wires apart at the connector and see if it starts. If it does then there is a problem with the switch or wires leading to the switch. If it does not start then you have a problem with the wire going to the magneto or the magneto itself.

    This is of course assuming there are no other problems like a carb, fuel, compression problem etc...
  5. Potchkins

    Potchkins LawnSite Senior Member
    Messages: 570

    have you checked the plug wire?
    it might have broken down
  6. General Grounds

    General Grounds LawnSite Senior Member
    Messages: 902

    :blob3: sounds like a bad ignition coil, tony
  7. winecountrybum

    winecountrybum LawnSite Member
    Messages: 3

    Ok, problem is solved! Thank you to Richard Martin. The problem was an intermittent short in the wire going from the ignition coil to the on/off switch. Ran a new wire, and now everything works fine. Thank you everyone for the help.
  8. 15001

    15001 LawnSite Member
    Messages: 11

    Does anyone know what the air gap spec is for the ignition coil ? need info please
  9. windflower

    windflower LawnSite Bronze Member
    Messages: 1,098

    I set mine for the thickness of the cardboard box it came in. Seems to work fine.
  10. Porcupine Lawn and Snow

    Porcupine Lawn and Snow LawnSite Senior Member
    Messages: 334

    Last edited: Mar 19, 2014

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