Electronic Ignition Troubleshooting

[Ajax]

A friend just bought a Pearson 30. During the delivery home, the engine simply quit and never restarted.

I visited the boat, and discovered absolutely zero spark on any of the plugs.
This boat has been equipped with Indigo electronic ignition.

The diagnosis should be simple, I'm just looking for a sanity-check:

The coil has power.
The ignition module external to the distributor has power.
If you ground the coil wire to the engine block, the coil is producing spark. This means that the distributor is receiving spark from the coil.
No spark is being distributed to any of the 4 plugs.

My diagnosis is that the trigger module inside the distributor has failed.

Comments?

[edwardc]

Agree that the EI is your most likely suspect. But two other possibilities are

- The rotor
- Carbon tracks inside the cap

Since these are cheap parts, and easy to test, I'd eliminate them first. Just repeat your spark test while cranking, but do the test at the wire coming off the coil instead of at the spark plugs.

[Dave Neptune]

See the light

Ajax, first check under the cap. The Indigo is a "photo optic trigger" so check to see that all is in place, IE the shutter and the "LIGHT", just to be sure they're in place.

Also on the later Indigo units there is really nice feature, a functionality light on the end of the "box" it is a red LED and will flash while cranking if it is getting a signal.

You can also position the shutter window over the light and have it so with the c-adv you can move the shutter back and forth through the light, no spark no good.


Dave Neptune

[Ajax]

Ajax, first check under the cap. The Indigo is a "photo optic trigger" so check to see that all is in place, IE the shutter and the "LIGHT", just to be sure they're in place.

Also on the later Indigo units there is really nice feature, a functionality light on the end of the "box" it is a red LED and will flash while cranking if it is getting a signal.

You can also position the shutter window over the light and have it so with the c-adv you can move the shutter back and forth through the light, no spark no good.


Dave Neptune

Dave,

The owner has replaced the cap, rotor and plug wires with no effect.
He has the older Indigo EI kit. The module doesn't have the LEDs.

I called Indigo and they're saying that the optical trigger is working, because it's firing the coil. I'm not really sure I agree with this. I had the same system on an old Ford pickup truck and the trigger module in the distributor had failed in the exact same way.

We will check again to make sure that the trigger is properly mounted in the distributor.

I might get generous and offer to drop my own distributor into his engine for a test.

[Dave Neptune]

Hmmm?

Ajax, what did you say or Indigo say that leads them to say the trigger is working?

Did you try moving the shutter and get a pulse to the coil?

I've worked quite a bit with photo optic systems and have only replace a couple of "photo triggers".

The system is very simple the signal from the photo trigger goes to the box and the box is the switch (like the points) that sends the pulse to the coil.

Dave Neptune

[ndutton]

The coil has power.
The ignition module external to the distributor has power.
If you ground the coil wire to the engine block, the coil is producing spark. This means that the distributor is receiving spark from the coil.

I don't think grounding the coil (secondary?) wire to the block is an effective test for system function. The coil needs to produce enough energy to jump the air gap on the spark plug, like a little bolt of lightning. The way it does that is it builds up a charge when the - terminal is grounded (points or EI closed, the + terminal is always energized during operation) then when the - is removed (points or EI open) the coil dumps the full charge, like 20,000 ~ 40,000 volts depending on the coil you have.

[Ajax]

Ajax, what did you say or Indigo say that leads them to say the trigger is working?

Did you try moving the shutter and get a pulse to the coil?

I've worked quite a bit with photo optic systems and have only replace a couple of "photo triggers".

The system is very simple the signal from the photo trigger goes to the box and the box is the switch (like the points) that sends the pulse to the coil.

Dave Neptune

I told them that the coil is sending spark to the distributor, but nothing is coming out of the distributor on any of the 4 spark plug leads. The engine died very abruptly.

No, I didn't move the shutter.

Ok, so it sounds like the EI system is functioning normally. After replacing the plugs, wires, cap and rotor, what would prevent spark from being sent to the plugs?

I'm going to try again to find spark on the plugs. Maybe I was just doing a poor job of grounding them.

[joe_db]

With everything hooked up, take the coil wire out of the distributor and hold close to the block. Crank the engine. If it sparks, then the Indigo, coil, etc. are good and the issue lies downstream. If not, then the issue is upstream.
I had endless issues with my Indigo unit that broke down as follows:
1. Burned out coils. (this was in the dark days before we knew about ballast resistors)
2. The unit itself died once.
3. Burned out coil wires. Apparently the Indigo had a hot enough spark to degrade the wire from the coil to distributor. It was gradual - it slowly got worse and worse until the boat would not start.

Try a new coil wire. For a test pretty much any wire will do, but don't touch while it is running

[JOHN COOKSON]

Ok, so it sounds like the EI system is functioning normally. After replacing the plugs, wires, cap and rotor, what would prevent spark from being sent to the plugs?

The coil is firing when the rotor is between contacts inside the distributor cap.
Check the timing. The distributor may have slipped and rotated.
Not a very likely scenario but have a look anyway.

TRUE GRIT

[edwardc]

...I'm going to try again to find spark on the plugs. Maybe I was just doing a poor job of grounding them.

Try something like this with a spare plug. It can become a permanant spark tester.

[Dave Neptune]

Clarity

Ajax, when you crank the engine do you get spark from the coil? Or just if you work the wires on the coil?

Dave Neptune

[67rway]

I apologize in advance if this is ill-received, but I've been taught to assume nothing...

When cranking, does the rotor turn?

[Dave Neptune]

You bet it does

67, absolutely it turns. It must rotate with the engine to maintain the timing.

Dave Neptune

[joe_db]

I think he meant does this individual rotor turn, not all of them

As for the spark, it should be bright blue and jump at least half an inch. A yellowish 1/4" spark is not enough.

[Ajax]

Ajax, when you crank the engine do you get spark from the coil? Or just if you work the wires on the coil?

Dave Neptune

I don't understand the second half of your question.

I removed the coil wire where it connects to the distributor and grounded it to the engine block. I got a blue-white spark when cranking the engine.