85 hp force front CDI box (1 & 2) only works with #3 box kill wire disconnected

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CowboyBill

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[FONT=&quot]First I apologize for the long post! Here?s my deal, I?m a heavy diesel mechanic by trade and I used to work on passenger cars but these outboards make me feel like a beginner. I need some help from the great minds/technicians on this forum! I have a 1987 85 hp Force that was a ?Good Deal?. Ran ok the first time we went out but not since. Would not run well then die when putting it in gear. Found Stator was bad 750oms on one set of leads, 0 on the other so I put a new one on. Now stator is good, trigger checks out within specs on all 3 pairs of wires. New plugs, cleaned all connections and verified that the connectors are soldered and/or crimped well. Cylinder 2 has no spark. Based on some of the great tips I?ve read here, I checked out the kill wiring from the CDI boxes and have no power coming to the white wires at any time. Unplugged these wires from the junction block and all 3 cylinders spark and the engine runs like a champ. Connecting the wires again and it dies. Disconnecting them again and starting it, again all 3 fire and connecting the front CD box (1&2) while the engine is running and there is no change and I can kill the engine with the key and restart it. But when I connect the rear (#3) it misses like crazy. Is this an indication of a bad CD box? Why does cylinder 2 stop firing when I connect the kill wire for the box that controls cylinder 3? What am I missing here? In a pinch can I run it with only the 2&3 CD box kill wire connected? Please help!!![/FONT]
 
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Jiggz

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From your description, it is very possible the shunt wire or kill (white) wire for #2 CD module (powering #3 cylinder) is shorted internally. There is supposed to be some kind of blocking diode which sometime fails and causes problems like yours. There are two options I can see that will fix your problem. But before delving you need to make sure the kill white wire for #2 CD module (one powering #3 cylinder or bottom cylinder) is not grounded somewhere else. Also there is a spare circuit on #2 CD module that is not in use (unlike on #1 which uses both circuits to power #1 and #2 cylinders) which you can try using. Just make sure you also switch the wiring on the trigger wires and the output wire to the coil.

1. You can still ran the motor with just the kill white wire for #1 CD module connected and still be able to shut off the motor with the ignition switch.

2. You can go ahead and replace #2 CD Module.
 
jerryjerry05

jerryjerry05

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Try swapping the packs around.
Since #2 is a no fire???
The bottom pack doesn't use the #2 and it should be able to fix the problem.
 
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CowboyBill

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one or two more questions, if #3 CDI Is failed why is it killing the spark on the one for cylinder #2, is it back feeding that circuit? And while i was goofing around with the kill wires i got zapped HARD by touching the end of the #3 cyl cdi should that much current be coming out if those?
 
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CowboyBill

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two more questions: 1) if the rear unit is bad why does cyl#2 quit sparking on the front one, is it back feeding the circuit?
B) when i was goofing around with the kill wires i got zapped hard, should that much current be at that wire? Thanks Again
 
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Jiggz

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Oh yes, if the motor is running the kill wire does get energized and can seriously zap if touched. The purpose of the kill wire is to divert the high voltage from the CD module to ground (shunt) whenever it is connected to ground thus causing no voltage to flow to the coil hence killing the spark and then the motor.

The ignition switch has two "M" terminals. One terminal connects to the kill white wires while the other connects to ground. When the ignition switch is turned off, you basically close both the "M" terminals together, i.e. shunting the kill white wire to ground. When you turn the ignition to "On" all you do is basically "Open" the two "M" terminals thus allowing the engine to run.

As for your question on why connecting #2 CDM kill wire results in misfires on #2 cylinder, it could be internal electrical problem with #2 CDM. And the only way to find out is to get another good known working CDM and replace #2 CDM. Or try using the spare circuit.
 
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CowboyBill

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Jiggz I thank you for your personal insight!!! I'll get one tonight. side note: I work at the R&D facility of a major manufacturer of heavy duty on/off highway trucks and we get all kinds of new and old designs that come through here and part of my job is figuring how, why and what makes these things work and or not work but these outboards are greek to me. Maybe it is because I have had little exposure. At any rate I thank you and all of the knowledgeable folks on here for helping and not making me feel like a bonehead for not knowing. you are stellar people!!!
 
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CowboyBill

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I'm looking for good CDI parts and see the $230+ prices but find a used one for an 89 MUCH cheaper, but a different part number. do you think an 89 would work? Know of anyone who has a known good used one for a user friendly price :) ?
 
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Jiggz

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Let us know of the final outcome. So that people who have the same problems with the same symptoms can quickly diagnose and repair their problems.
 
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Derrick Fronckowiak

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Jul 15, 2015
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Cowboy Bill, you might find considerably cheaper CD packs on eBay, used of course but most sellers will let you return them if they don't work. I picked up a used pack for my 90 HP Force for less then $100 (free shipping too), it works fine. When someone parts out an engine (usually because of major seizing, thrown rod, etc.) they usually make money despite pricing the individual components low price. It's win-win the way I see it.
 
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CowboyBill

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Understood about buying and selling, my bad! . I think I resolved it. left the rear box kill wire unplugged and have good spark on all 3. we went out on Friday and it purred like a cat. runs nice. I may still get another CDI module to be safe. thank to you all!
 
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