Troubleshooting Ignition
 

My new engine won't start and it's not making a spark. Well, it tried once or twice but there's really no spark. My green wire looks ugly but it is passing electricity. When the starter is run there is pulsing between the two conductors in the green wire, but it is very faint. Up to only .018 volts.

My coil has a sticker on it warning not to put a test meter between the two small connections. Is this just a problem becuse if the CDI unit? I mean, if I disconnect the CDI then can I safely test resistance values of the coil. And what should the resistance values be for my coil?

Jim,

The warning is so you won't fry a dwell meter expecting 12 Volts ... with the 460 Volt thunderbolts from the CDI-unit ...

The coil should read 0.4 - 0.6 Ohms on the primary, and 650-790 Ohms on the secondary.

Are you getting the 0.018 Volt signal at pins 3 and 6 of the CDI-unit connector?

Warren,

There is confusion about what terminals are where on the CDI. Bentley certainly disagrees with the configuration on my system. Seen as three pairs, one of the outside pairs are simply the two conductors in the coaxial green cable. These should be making a pulse and they are, but nearly too faint to read with my meter. .018 volt was the highest peak I saw. Unless I'm reading my meter wrong.

Similarly, the primary resistance of my "coil" is hard for my meter to measure, and hard for me to understand, frankly. There are five resistance scales to choose from (named 2M 200K 20K 2K and 200). Primary resistance of my coil is zeros everywhere, except a "00.7" reading on the "200" scale.

Secondary is 688 ohms, so that's fine. If primary resistance is just a little high (.7 volts), then wouldn't it still run?

Your coil sounds fine ... very few inexpensive DMM's can read accurately below 1 Ohm ... your test leads probably measure 0.1 or 0.2 Ohms, and that is included in the reading!

As for the pulses ... were you reading them on a 2 Volt AC scale? They would read rather erratically on a DC scale!

Grounding, or lack of a good ground connection at the engine, or distributor sounds like the likely problem. Is there a braided shield connection from the CDI-harness at the distributor, or just the green wire and its' connector?

It lives!!! I'm going to go heat up some rings, be back in a bit.

So, what was the problem?