Will not start

So I put the repaired wire in, and I’m getting full cranking power now, and I think that solved the voltage drop. We soldered and put heat shrinking tube on the wire.

Now, I’m seeing this. When I put a test light to the positive terminal, it’s fine and lights up perfectly. When I put it to the negative terminal, it almost never lights up, and I don’t see that pulsation you would expect on that side. I checked the continuity, and there is continuity between the negative terminal wire, and the pin in the 14 way connector for the ignition coil driver wire. I also cleaned it a bit to help, but it didn’t do anything. What does this mean? I’m not getting pulsation which explains the no spark, but why no pulsation?

So you're making progress.

The 0 volts on the negative terminal means the computer has it grounded so the electromagnetic field is building up, getting ready to make the spark. That line goes open circuit for just a fraction of a second, much too short to give the test light a chance to start to glow. When that happens, the magnetic field has no choice but to collapse instantly, and that is what generates the high voltage in the coil's secondary. When you have a problem on the negative side is when you see the test light is bright constantly. That means no magnetic field is building up in the coil.

The only accurate test in that area is to pull the distributor wire out of the distributor cap, and check for spark there.

I did pull the distributor wire out, and held it against the metal of the engine, and there was zero spark. I truly am getting consistently zero volts from the ignition coil, although I could swear when I last performed this test a few months ago, you were able to see the pulsation with the test light.

Again, even when I’m starting up and put the key in the on position, I don’t see any light or voltage on the negative terminal.

The only other possible cause is the ignition coil is open. You can verify that with a resistance measurement. The typical value on the primary side is real low, as in probably less than 12 - 15 ohms. If that is okay, check the secondary between the negative terminal and the coil wire terminal. That one is usually around 15,000 ohms or higher. If you find it's real low, the secondary is shorted. That type of failure isn't real common.

I tested the primary and secondary circuits on both the original and the replacement ignition coil. Both primary circuits were fine. For the original secondary, it read about 8000 ohms. For the replacement secondary, about 9200 ohms.

In my photo, the original is on the right (1306). The replacement (1006) is on the left. Could the different part numbers mean I was given the wrong coil?

Manual calls for 1.34 ohms to 1.55 ohms on the primary resistance and I’m also getting greater than 1.6 on both coils.

Manual calls for 1.34 ohms to 1.55 ohms on the primary resistance and I’m also getting greater than 1.6 on both coils

I got it! It was so obscure I never saw it before. but when I put the engine mount back in last year it was on top of the negative terminal wire. I got the wire out of there, taped it up, and it runs!

Bet that feels good.

We never measure the resistance of an ignition coil except to verify a suspicion. The little higher your primaries are reading is irrelevant, plus, you have to add the resistance of the meter leads. That is often as high as two to five ohms.

Very happy to hear you solved it.

Thank you so much for all of your help! I really do appreciate it, and I know I can be difficult to work with.

These are the kinds of problems I enjoy figuring out. Please come back and see us with your next one.