Ignition Coil

[Themanofsteel]

I have a 85hp Force Outboard 1988. I recently replaced the top Ignition coil because it wasent giving a good spark thus my boat wouldn't go faster than 15mph. I replaced it with a used one I bought online which fixed the problem however that one seems to be going out now too. My question is what causes the ignition coil to go out and not give a good spark. Is something in the electrical system shorting it. One would assume age but the other coils seem to be holding strong as old as they are.

 

[pnwboat]

You can swap #1 coil with #2 coil and see if the problem moves with the coil or stays with #1 cylinder regardless of which coil is used for #1 cylinder.

 

[Themanofsteel]

Ok. I'll try that.

 

[jerryjerry05]

The trigger leads, very thin wire, under the shrink wrap they can break and not allow the cyl. to fire.
​Replace all the connectors.

I've only seen 1-2 coils go bad ever.
The same cyl. and the coils going bad?
I'd test the voltage going into the coil.
outboardignitiondotcom has procedures for testing your system.

 

[Themanofsteel]

jerryjerry05 Thanks

 

[Themanofsteel]

Here is a GIF link showing the spark intermittently weakening. https://www.dropbox.com/s/95lor8y7fen2at3/Spark.gif?dl=0

 

[jerryjerry05]

First swap the packs around and see if the weal spark follows the pack???
​Then do the stator tests.
Then test the rectifier.

 

[Themanofsteel]

I tried that yesterday. All the sparks seem fine now. No weakening. But this has been a reoccurring issue the last couple of weeks. I take my boat out and it runs fine but suddenly looses power. When I test at home I see a weak spark. But a few days later and no weak spark. It seems to be a intermittent problem that is hard to diagnose. Any suggestions on how to troubleshoot this.

 

[Themanofsteel]

FYI I've tested the engine compression and it's good. All cylinders are 120+ compression.

 

[Jiggz]

Intermittent spark problems are really very hard to diagnose but not impossible. But it'll sure take a lot of time to diagnose it accordingly. As previously mentioned, switch the coil with another known good working coil, i.e. #2. Keep the coil switched and then do your normal running. If the problem arises (weakening sparks) did it stayed with #1 or did it moved to #2. Obviously, if it moved to #2 then the coil is the problem. If it stayed with #1, then the coil is NOT the problem. Instead it could be the CDM or the trigger.

Next, switch the CDM. Note since this is a 3 cylinder motor, #1 CDM feeds #1 and #2 coils while the #2 CDM only feeds #3 coil and the other CDM circuit is a spare. You need to physically switch the CDM's instead of just the wiring. This is with the assumption the spare circuit on #2 CDM is a working one.

Note again, since you will only be using one CDM circuit (when moved to #2 CDM position to feed #3 coil) on the previously #1 CDM and the suspected problem is with the #1 CDM circuit (previously feeding #1 coil), use the #1 circuit to feed #3 coil. In this manner if the problem arises again and it moves to #3 then you know the problem is the #1 CDM circuit. If this is the case, no need to get a new CDM yet, instead use the spare CDM circuit.

However, if the problem arises and it stayed on #1 after the CDM switched, then it is obvious the problem is with the trigger or magnets.