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View Full Version : How to check for a bad coil


DJL50
04-12-2007, 10:53 PM
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.

khouse
04-12-2007, 11:53 PM
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.

MowerMedic77
04-13-2007, 06:32 AM
With an in-line spark tester like this one
http://www.toolfetch.com/Category/Automotive/Spark_Testers/LIS20610.htm?utm_source=Google&utm_medium=GS&utm_campaign=toolfetch&cm_ite=inline%20spark%20tester

I would look around for one that is less expensive I have picked up similar on sale at Harbor Freight for $2.00

DJL50
04-13-2007, 08:00 PM
With an in-line spark tester like this one
http://www.toolfetch.com/Category/Automotive/Spark_Testers/LIS20610.htm?utm_source=Google&utm_medium=GS&utm_campaign=toolfetch&cm_ite=inline%20spark%20tester

I would look around for one that is less expensive I have picked up similar on sale at Harbor Freight for $2.00

Thanks!

So what you are saying is. If I have spark, the coil is good. It is not possible for a coil to be weak or something along that line.

MowerMedic77
04-13-2007, 08:55 PM
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.

khouse
04-13-2007, 08:57 PM
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.

ed2hess
04-13-2007, 10:33 PM
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.

General Landscaping
04-14-2007, 12:09 AM
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.