No spark from coil, I've tried everything!

[chocolate_supra]

Well, at least I think I've tried everything. I have a '72 240Z that ran just fine a few months ago, but was very, very gross. I stripped the engine compartment to begin a long overdue restoration, and with everything cleaned up, painted, or replaced I put it all back together and now I have no spark from the coil. I've been reading forum posts for days trying to figure what's going on and have since

- double-checked the wires to my dash and tach,

- confirmed the points have power,

- checked the wiring inside the distributor,

- confirmed power at the coil (9v in "on" and 12v in "start"),

- replaced condenser and coil, spark plug wires and coil wire

and still no spark from the coil.

I am at wits end, as is my father who is a pretty seasoned automotive electrician. We've both exhausted everything we know and now need some Z-specific wisdom here. What am I not considering?

[pwd]

- Check the Point gap with the Cap off and crank the engine. Verify gap setting is correct.

- Disconnect the Condenser and do a continuity test on it. It should appear open. If not it's defective - replace it.

Edited February 7, 2011 by pwd

[chocolate_supra]

Thanks for the reply. Just checked the condenser for continuity and it's fine. Also checked the points and they're gapped correctly. Any other possibilities?

[d240zx2]

Did you mess with the engine AT ALL? It appears you may have removed the distributor for your project. Did you turn the engine while the dizzy was out?

Find TDC. The dizzy rotor should be pointing dead straight to the front of the car. If not, you're dizzy timing has been disturbed and needs to be re-done.

[chocolate_supra]

You're right that I removed the distributor, but we made absolutely sure not to spin the engine, specifically so the distributor would go back in correctly. It just came out, got scuffed and painted, then went back in.

[ajmcforester]

OK you got power at the points, yet you claim you are not spark from the coil? That makes little since. You would need power to travel from the coil to read it at the points.

Unplug the wire from the coil to distributor and test the coil at that point, any power? You should read something if you did at the points. Hook the wirer back up.

If you got power next hook your timing light up and see if it flashes if no unhook a wire running to a plug and use your tester to see if you can get power when the engine turns. If not it's some thing not right with the distributor.

[FastWoman]

Try this:

Connect a 12V light bulb across the terminals on your coil, and crank the engine. Does the light flash on and off? If so, then you've confirmed you're delivering current to the coil and that you SHOULD BE getting a spark out of it. If you're not getting a spark, even when the bulb is flashing, then you've got a bad coil.

[Bonzi Lon]

My electrical knowledge is limited, but I do know you will need a 'ballast resistor' in the mix. Is the ballast resistor wired in?

Bonzi Lon

[Ralphy]

Definitely going to be needing that ballast resistor wired in correctly... volkswagen beaverton vw

Edited February 10, 2011 by Ralphy

[chocolate_supra]

The ballast resistor is wired in, and while I'm not sure how to check the resistor itself to see if it's working, I think that since I get 9V at the coil in the "on" position and 12V at the coil in the "start" position, that the resistor is wired right. Is that correct?

I'll try hooking up the lightbulb to the coil today and seeing if it flashes while turning over.

[chocolate_supra]

Okay, here goes:

The insulation on the tip of the new wire in the distributor was so thick that when the distributor cap was on, the cap would push the cable into a part of the casing where it would ground out. So with the cap off and testing the points, everything checked out, but with the cap on it would kill it. Strange how the smallest things can mess it up. The engine now runs for the first time since we've cleaned it up! Thanks to everyone for responding, and I'm sure you'll be hearing a lot more from me as I continue fixing this beauty up.

[ajmcforester]

I'm glad you found it. I thought it had to be something with the distributor, what you stated at first didn't make since, and I know what your talking about the first time I rebuilt my distributor I did the same thing. I took it apart 3 times be fore I figured out why