How to check for a bad coil

Discussion in 'Mechanic and Repair' started by DJL50, Apr 12, 2007.

  1. DJL50

    DJL50 LawnSite Senior Member
    Posts: 268

    Hello!

    How do you check the coil to see if it is good or bad. I am not having problems at this time. Just wondering how it is done. I own mostly Kawasaki if that makes a difference.
     
  2. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    Sometimes it's different for different models. But I remember about 6 months ago here on the forum (i think) a guy tested his coils by holding onto the plug wire.
    If you don't pull your arm back then the coil may be bad. If you pull your arm back at the speed of sound then the coil is weak. If you jerk your arm back at the speed of light then the coil is good.
     
  3. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Posts: 1,164

  4. DJL50

    DJL50 LawnSite Senior Member
    Posts: 268

  5. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Posts: 1,164

    I look for a bright(orange) light if its faint or very hard to see then I would replace. Remember it takes less voltage to jump the gap on a plug that is removed from the cylinder and set up against the head bolt(not a good coil test anymore). So the in-line test light is a quick and easy test and forces the coil to send full voltage to the plug.
     
  6. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    Most of the time a coil either flat out dies. Or it will stop working after it heats up. It is more common for a battery ignition coil to be weak from low voltage. I didn't mean to be a smart a$$ on my other post. But since you weren't broke down I decided to lighten things up.
     
  7. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,140

    I am 2 for 2 in determining they are bad.....if they have no resistance with volt meter I conclude they are surely bad. And all new ones have some resistance ....but this is very limited sampling...all echo stuff.
     
  8. General Landscaping

    General Landscaping LawnSite Senior Member
    Posts: 802

    Don't forget to unhook the engine kill wire from the rest of the machine to eliminate the possibility a stuck switch or chafed wire.
     

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