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240z, no spark from coil


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Hey all, need a little help. Just got my first 240z, been sitting for 20 years. Got it started, then replaced condensor, points, cap and rotor. And now i have no spark from the coil. Has 12v out the coil from secondary, but drops to about 9v when turning over. The points open/gapped correctly, its timed correctly. Could it be resistor? Condensor wiring issue? What would cause no request for spark?

Thanks

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In the original system, when cranking, it's supposed to bypass the ballast resistor entirely and give a full 12 volts to aid in starting. Once the key is back to the "on" position it drops the voltage back down.

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Power is supplied fron the ignition through the coil to the points and to ground. The points open and close, opening and closing a ground to the power through the coil. When power flows through the coil to ground through the points, a magnetic field builds in the coil. When the points open the field collapses and induces a high voltage spark.

 

Look at the points and crank the motor over. You should see sparks if current is present.

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9V while cranking is normal. YES, bypass the resistor while testing. You can run it for 30 seconds without the resistor. If it starts when bypassing the resistor, then most likely the START circuit is bad. It automatically bypasses the resistor via the Ignition switch S position, but the switch could be bad, or the wiring corroded.

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When you turn the ignition switch to the on position, before cranking it over, does the e-brake light come on/flash? There should be an alarm sound as well. if not, Check the wiring into/out of the ignition switch. just had that problem tonight on a friend's Z, the wire sending power to the ignition circuit had corroded and broken. The result: it would turn over just fine, but no power to the coil.

 

Something to think about...

 

Edit: also, while you're in there check/replace the fusible links. It'll save you a step if you have any electrical issues in the future.

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so this was runnnng before ? then you put new stuff in? if yes put the old stuff back in and see if it works.

 

I have done this a few times its a loose connection usually and then it runs. then I install the new stuff then works OK and can never figure out what I did wrong.

 

if you have a single point distributor get a pertronix kit for it then you dont have to worry about this.

 

12volt at coil with Key ON

also should have 12volts on the HOT START wire when key is in START .

 

you can remove the starter wire then ck this out.

soemtimes the connecter at bay of key switch can be loose wiggle it

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