Testing a coil and CDI Box?

[shane-r13]

Ok so I just tested coil again. One lead into plug cap and one on power into coil. No reading. Also tested cap to ground and got no reading as well.

Then I test coil ground to coil power in and got this.

Then I test spark plug cap to spark plug cap and got this.

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[frankr]

Looks good, and consistent with what I expect. I say in all probability that coil is fine.

Hey, thanks for some sensible test reports. It’ surprising how many people don’t know how to make simple tests like that.

[frankr]

No insult intended, but are you sure it doesn’t have spark? CDIs are not all alike, but most of them have a real thin white spark that you can’t even see in daylight. When my chainsaw wouldn’t start, I checked for spark and would have sworn there was none. After spending way too much time on it, I realized it did indeed have spark and there was some other reason it wouldn’t start.

My Johnson will throw a thin white spark an inch long with ease. But the chainsaw is more like an eighth of an inch and real thin.

Hate to admit it but "somebody" wasn’t paying attention and filled the chain oil tank with fuel and filled the fuel tank with chain oil. Sheese, what a dummy.

[outbdnut2]

Like Frank said, that spark on some CDI motors (not sure about this one) is very short duration, and can be hard to see. I have had several CDI motors where I had to shut the garage door and turn out all lights anywhere near the motor to see the spark jump in a spark plug gap opened to 1/4 inch.

I have an Arctic like yours that a friend gave me. He was told it needs rings. I haven’t done anything with it yet, but I could see if it has spark and then take some ohm-meter readings and see how they compare to the ones you posted; but my schedule will not let me get to it for a couple of weeks.
Dave

[shane-r13]

Well no I guess I don’t know. Besides using my gap tester and just plain old trying to start it I assume not spark since I see none and it doesn’t start. I’ve checked all grounds and wires for fraying, I charged my battery and it hasn’t helped. I also was doing the spark test at dusk last night and still didn’t see any sparks. I was also looking for shorts and sparking else where and seen nothing.

Shane

[shane-r13]

quote outbdnut2:

Like Frank said, that spark on some CDI motors (not sure about this one) is very short duration, and can be hard to see. I have had several CDI motors where I had to shut the garage door and turn out all lights anywhere near the motor to see the spark jump in a spark plug gap opened to 1/4 inch.

I have an Arctic like yours that a friend gave me. He was told it needs rings. I haven’t done anything with it yet, but I could see if it has spark and then take some ohm-meter readings and see how they compare to the ones you posted; but my schedule will not let me get to it for a couple of weeks.
Dave

I’ve tested in the evening darkness and still seen nothing. I’d really appreciate the meter readings to compare. Would be helpful since there isn’t much on the net.

Shane

[shane-r13]

If i put a meter into a plug end and then the other end of meter onto the positive or negative of my coil, should i not get a reading? I took an old coil i had from a td20 and did just that and got like 4.5 on my meter, when doing that on this Suzuki i get nothing? While i understand they are different motors but would the principal be the same for the coils?

Shane

[frankr]

If you are suggesting checking to the input or ground terminals, then no there should not be any continuity to the plug wires. The primary and secondary windings are isolated from each other—if it is as I suspect it is.

[shane-r13]

Well I’m lost. I’ve checked this and that. Pulled all the wires out checked the grounds disconnect and re connected the grounds. Disconnected and reconnected all wire connects. Stripped all the protective wiring from wire bundles and no frayed our loose connections. Have power coming from mag to cdi, have voltage at the coil inputs but no sparks.

Wish it was just the coil that’s easy to replace.

[outbdnut2]

The insulation could be breaking down inside the coils, shunting the spark before it can build to a high enough voltage to jump the spark plug. Unfortunately, you can’t visually see this, and you can’t diagnose it on an Ohm-Meter.
Dave

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