G9 doesn’t run consistently

[Paulzy123]

Hello.

Looking for some guidance.

Rebuild the engine on my G9 this winter as it was smoking pretty bad.
Anyways. It was running great last year.
This year can’t get it to run consistently.
It’s getting fuel to the carb and the carb has been rebuilt.
Some days I can hop on and it will run, the. Out of no where it doesn’t.
Purchased an inline spark plug tester.
When it won’t run it doesn’t have spark.
Checked and cleaned all wiring harnesses to no avail.
Come back a few hours or days later and it fires right up and runs great.
Then for no apparent reason won’t start.

Wondering if this would be a faulty control module?
Not sure how to test it.

Any ideas?

[Paulzy123]

Also considering maybe a bad coil?
Is there a way to bench test a coil?
I know it’s not factory. Pretty sure Chinese.
Spark plug is also not an NGK if that matters.

[CP241]

Use a NGK plug.

Check resistance of the coils in the coil. Should be around 4 ohms between the two terminals if I remember correctly.

Remove the spark plug cap. It unscrews from the end of the wire. You should have about 10k ohms from either terminal to the end of the cable. And you should have 5k ohms through the spark plug cap itself

[Paulzy123]

Originally Posted by CP241

Use a NGK plug.

Check resistance of the coils in the coil. Should be around 4 ohms between the two terminals if I remember correctly.

Remove the spark plug cap. It unscrews from the end of the wire. You should have about 10k ohms from either terminal to the end of the cable. And you should have 5k ohms through the spark plug cap itself

Always appreciate your knowledge CP241.
I’ll be using your advice this weekend when I’m back at the cottage.
Can the spark plug wire be removed from the coil? Most coil sets I’ve seen for sale have the wire connected.

[CP241]

No the wire is part of the coil. But the cap is separate and just screws off, there’s a little wood screw looking thing inside it. Sometimes the end of the wire gets crusty and you can just cut a half inch off the end and screw the cap back in

[CP241]

My guesstimates were pretty close :)

Here’s actual specs from the service manual.

[Paulzy123]

Originally Posted by CP241

My guesstimates were pretty close :)

Here’s actual specs from the service manual.

Thanks very much good sir.

Will continue the diagnosis this weekend.

[Paulzy123]

Hey gang.

Back from the cottage.
Did all the measuring and the coil and spark plug cap are in range.
Changed the plug to an NGK.
Trimmed the spark plug wire and resecured the cap.

Cart behaviour stayed the same.
I did notice that while trying to start I could here a few soft booms come form the engine. Assuming this was a mild backfire. But odd that it was so soft or muffled. Not the loud pop I’d expect.

So I’m baffled. Could it just be a broken wire?
Or the control module?

[CP241]

If all the connections are good, coil is good and pickup coil tests correctly (495-605 ohms between the white/red and white/black at the ignitor connector) then it’s probably the ignitor on its way out. That’s the only part you can’t test, just replace and hope.

Chrysler HEI conversion is always an option and works fine, but the oem ignitor is better. I’ve done it both ways and prefer OEM.

[Paulzy123]

Hello gang.

Just to close this thread.
Issue is now resolved.
I had replaced the ecu and the issue persisted.
I kept checking all wire and connectors.
Found the ground wire in the evu connector was not making a good connection.
Corrected the connection and cart now runs problem free.

Thanks again for all the tips.