9n no spark follow up

[ffinmich]

Hi, have a 9n that was converted to 12 volt a few years ago, has 12 coil. Has run great never trouble starting. So now no spark. If I run a wire from the power side of the battery directly to the top of the coil, it fires right up. So maybe the switch, I replaced the switch with one from a tractor that does start and still nothing. So, what should I look for now.
Thanks

 

[Bruce (VA)]

Randomly replacing parts usually gets you the result you just got.

Get out your meter. You should see 12.65 volts at the battery. With the key on, and the points open, you should see the same voltage at the coil. If you do not, then check the voltage from the battery to the switch to the resistor and then to the coil. Somewhere in that circuit, will not see 12.65 volts.
75 Tips

 

[ffinmich]

0 volts at the coil, checks 12.5 at the switch

 

[Roger in Iowa]

Both sides of the switch?

 

[old]

As asked both sides of the switch?? Also does it still have the factory ballast resister in the circuit?? If it does it could be bad or the wire is bad at some point if the resister is still good

 

[Jim WI]

(quoted from post at 14:59:54 11/18/23) 0 volts at the coil, checks 12.5 at the switch

Use the meter to track the wiring back to find where the voltage goes to zero. Is the ballast resistor getting hot or is it cold? If it's hot, there is likely a short to ground somewhere. My guess is a bad ballast resistor but check to make sure.

This post was edited by Jim WI on 11/18/2023 at 12:48 pm.

 

[Bruce (VA)]

Key off, battery voltage only on one side. Key on, you should have voltage on both sides. Do you?

If so, what's the voltage on both sides of the oem ballast resistor?
75 Tips

 

[Hobo,NC]

Hunting a unloaded circuit with a voltmeter can mislead you. You need a load to verify a good circuit. I use a automotive light bulb in a bottle in a Minute I can verifi a good circuit. The bulb in the mason jar pulls 4 amps the same load you coil pulls.

You should be able to use that jumper wire to find the issue also.

 

[Pete in Holland MI]

I added a small clearance light below my key switch on my Jubilee. It is wired on the on the switched side of my key switch. This way, I know there is power going to the coil, and/or, the key is on accidently. Has helped a lot recognizing the key is on and power coming from it.