turbofiat124
10-25-2019, 06:07 AM
I'm trying to troubleshoot why a co-worker's Kymco 90 Mongoose has no spark. This is my first troubleshooting experience with a CDI ignition system.
I've troubleshooted this bike for a couple of hours using the wiring diagram.
There are two wires going to the coil. The black/yellow wire comes from the CDI and is connected to the black pin on the coil. When the engine is cranked over, using a test light, the test light pulsates when connected to the black/yellow wire.
The green wire which goes to the green pin on the coil goes to the kill switch which finds it's way to ground when the switch is closed. At least that is the what the wiring diagram shows it. I disconnected it just to rule this out.
This is how the kill wire works correct? Just like a lawnmower engine there is a ground wire coming off the coil. When grounded, it kills spark to the engine.
On this ATV, this wire does the same thing, correct? Meaning if disconnected, the coil should still function. The coil itself is grounded through the mounting screw so this wire should have no other function. It is not necessary for the wire to be connected to the coil for it to actually function, correct? Does this make sense?
When the spark plug is installed on another engine and checked for spark it fires. But when hooked to this coil does nothing.
My co-worker said the bike just stopped running one day so he tried installing a new spark plug. He did not properly gap it but I did tonight.
He had someone else work on it before me. I have no idea what this guy did but he tried installing a new CDI and a new coil but still couldn't get it to fire. He gave up on it.
I also tested the old coil. It provides no spark either.
Interesting is when I touched my multi-meter to the primary and secondary connectors on each coil, the new one reads around 7.5K ohms. The original coil reads around 4.0K ohms. Does that mean anything?
So in summary:
My test light pulsates when connected to the power wire going to the coil when cranked over. Spark plug fires on another engine.
Tried the original coil and original CDI ignition box and the new CDI ignition box and new coil to no avail.
Couple of thoughts.
1) The new coil this guy ordered was DOA.
2) If the polarities are reversed on the coil by accident, could this short the coil out?
If your wondering why I didn't use the coil off one of my bikes, well we were doing this at work! I tested the new spark plug on our gasoline powered warehouse sweeper. If I had thought, I would have pulled a coil off one of my parts bikes. Or the bike my co-worker gave me.
Any ideas?
https://i.ebayimg.com/images/g/M44AAOSwpINZYsv6/s-l500.jpg
I've troubleshooted this bike for a couple of hours using the wiring diagram.
There are two wires going to the coil. The black/yellow wire comes from the CDI and is connected to the black pin on the coil. When the engine is cranked over, using a test light, the test light pulsates when connected to the black/yellow wire.
The green wire which goes to the green pin on the coil goes to the kill switch which finds it's way to ground when the switch is closed. At least that is the what the wiring diagram shows it. I disconnected it just to rule this out.
This is how the kill wire works correct? Just like a lawnmower engine there is a ground wire coming off the coil. When grounded, it kills spark to the engine.
On this ATV, this wire does the same thing, correct? Meaning if disconnected, the coil should still function. The coil itself is grounded through the mounting screw so this wire should have no other function. It is not necessary for the wire to be connected to the coil for it to actually function, correct? Does this make sense?
When the spark plug is installed on another engine and checked for spark it fires. But when hooked to this coil does nothing.
My co-worker said the bike just stopped running one day so he tried installing a new spark plug. He did not properly gap it but I did tonight.
He had someone else work on it before me. I have no idea what this guy did but he tried installing a new CDI and a new coil but still couldn't get it to fire. He gave up on it.
I also tested the old coil. It provides no spark either.
Interesting is when I touched my multi-meter to the primary and secondary connectors on each coil, the new one reads around 7.5K ohms. The original coil reads around 4.0K ohms. Does that mean anything?
So in summary:
My test light pulsates when connected to the power wire going to the coil when cranked over. Spark plug fires on another engine.
Tried the original coil and original CDI ignition box and the new CDI ignition box and new coil to no avail.
Couple of thoughts.
1) The new coil this guy ordered was DOA.
2) If the polarities are reversed on the coil by accident, could this short the coil out?
If your wondering why I didn't use the coil off one of my bikes, well we were doing this at work! I tested the new spark plug on our gasoline powered warehouse sweeper. If I had thought, I would have pulled a coil off one of my parts bikes. Or the bike my co-worker gave me.
Any ideas?
https://i.ebayimg.com/images/g/M44AAOSwpINZYsv6/s-l500.jpg