Need ignition coil resistance specs

My 96' Bayliner has a Mercruiser 5.7l v8 w/Thunderblot V ignition. I replaced the cap/rotor, spark plugs, plug wires, ignition coil and starter about 1.5yrs ago and the boat has been running great. I hadn't used it in about 3 months due to rainy weather and went to start it up yesterday but it wouldn't start. I live in Hawaii so don't winterize, etc. Batteries are nice and strong, I seem to be getting fuel (also tried starter fluid to help it along) and the engine turns over but doesn't start. I wanted to test the coil to see if it's gone bad but I don't know what the specs for resistance are supposed to be. Does anyone out there have a manual that says what the resistance should be on the primary and secondary windings?

I have a Sierra coil part #18-5438.

Thanks!

Re: Need ignition coil resistance specs

Do you have spark? Do you have power to the + terminal on the coil when the ignition switch is in the run position? Kill switch lanyard installed?

Primary Resistance .60-.80 Ohms
Secondary Resistance 9,400-11,700 Ohms

Re: Need ignition coil resistance specs

Thanks Don! There is power at the + terminal on the coil when the key is in the on position. I tested for spark at the plug wires and there was none. I tested for spark at the wire that comes off the center of the coil and there was none. I disconnected the tach to remove it as a possible problem (read that a shorted tach could be a cause) but still no spark. I removed the coil from the engine and used a multimeter (cheap radio shack unit is all I have) and here are the results:

Meter at 200 ohm setting read 1.1~1.2 on the primary winding (+ and - posts).
Meter at 20k ohm setting read 7.82~7.83 on the secondary winding (center and + post).

Based on the numbers you listed, it looks like the coil is bad...would you agree?

Re: Need ignition coil resistance specs

Jinxx said:

Based on the numbers you listed, it looks like the coil is bad...would you agree?

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Follow the troubleshooting flowchart in the genuine manual... Just shotgunning these systems will cost you far more than it should.

Chris......

Re: Need ignition coil resistance specs

achris said:

Follow the troubleshooting flowchart in the genuine manual... Just shotgunning these systems will cost you far more than it should.

Chris......

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I'm guessing you didn't read my original post. There's nothing "shotgunning" about what I've done. I'll wait for Don or anyone else who'd like to confirm/discount the coil being bad based on my measurements - thanks.

Re: Need ignition coil resistance specs

Based on the numbers you listed, it looks like the coil is bad...would you agree?

Click to expand...

Ayuh,... with power at the (+) terminal, there should be a spark from the hi-tension tower, when ya ground the (-) side...

Re: Need ignition coil resistance specs

Jinxx said:

I'm guessing you didn't read my original post. There's nothing "shotgunning" about what I've done. I'll wait for Don or anyone else who'd like to confirm/discount the coil being bad based on my measurements - thanks.

Click to expand...

I did read your first post, and there is absolutely nothing in there that says anything about following the trouble shooting flow chart. All it says is that you replaced a bunch of parts 18 months ago, boat ran great, now it won't start and you have taken a pot-shot guess at the coil....

If you'd like someone to say the coil's bad, take it to an auto-sparky and have him test it.... That'll confirm one way or the other.

BTW, a bad coil is just one of many reasons why you could have lost spark, hence my suggestion to test the system by the book...