Anemic Spark

[bbryan]

I have a Pearson 30 with an Atomic Four and Electronic ignition (Indigo Electronics). I estimate that the ignition is 7-8 years old, as it was installed by the previous owner. I have had no problems starting the engine until recently when, after running the engine for approximately 5 minutes, it shut down and I have not been able to restart it. I found that there was no spark at the plugs, and a very weak spark at the coil secondary. I had to almost touch the engine ground before I saw any spark at all. 10.7 V was measured at the coil. I connected a wire directly from the solenoid to the + terminal of the coil with the same anemic spark result. I replaced the coil with one ordered from Moyer Marine. There was no improvement in the spark intensity. Assuming that there was a problem with the electronic ignition, I connected a test light (actually a 12V LED) between the + and - terminals of the coil and turned the engine over. The light flickered, so I assume that at least the electronic ignition is doing its job of making and breaking the connection to the primary. I haven't delved into the distributor yet, as this is hard to get to on my boat. Saving that bit of fun for last!! However, I wanted to run this by the forum to see if there are any suggestions. Incidently, I changed the spark plugs out, and the engine probably has less than an hour or so on the new set. I wonder if there is a cause and effect somewhere there.

[Don Moyer]

Bbryan,

You've certainly done a good job of troubleshooting to this point, but it
intrigues me that you can measure a minimum of 10.7 volts at the positive
terminal of the new coil (presumably even when cranking the starter), that
the Indigo kit is making and breaking the primary circuit to ground, and
still you only observe a very weak secondary discharge from the coil lead.

If you haven't already done so, whenever our backs are to the wall as in
situations like this, I always recommend removing everything from the
positive and negative terminals of the coil except power to the positive
terminal and the lead to the points from the negative terminal (or to the
electronic ignition system). This would even include removing the field
flashing lead to the alternator, tachometer, bilge blowers, etc., etc.

If the problem persists after removing everything from the primary terminals
of the coil except for the ignition system, I think I would have to question
the "crispness" with which the Indigo kit is making and breaking the primary
circuit. You can isolate the Indigo kit by removing it completely and
replacing its function with a jumper wire from the negative terminal of the
coil which you can manually connect and disconnect to ground. This
connection to ground is accomplished by touching and removing the end
of the wire to the block or head. Each time you remove the jumper wire
from ground, you should observe a good secondary discharge to ground.

NOTE: Since the intensity of the secondary discharge depends on a very
positive and crisp making and breaking of the primary circuit, it helps to
grip the end of the grounding wire with a pair of pliers so you can more
aggressively touch and release the end of the wire to ground. Even with a
good job of making and breaking the primary circuit in this fashion, the
secondary discharge will not be as intense as normal since there is no
condenser in the circuit in this test. The discharge should however be
more intense than you're reporting.

If you do see a good secondary discharge in this test, it would clearly
indicate that something has failed in the electronic ignition's ability to
crisply and cleanly open and close the primary circuit.

Don

[msauntry]

How old are the expendables? (The distributor cap and rotor.) Got any spares around that you can throw back on? Same for the coil wires. They can go bad.