Merc 4.5 spark problems

[Trebor7]

First time poster to this site. Lot's of good info. Here's my problem
1979 Mercury 4.5 hp. Serial #5784***. Just purchased. Ran fine first time out, then lost spark. Breaker point was completely pitted and burnt. Replaced the breaker point (gapped at 20 thousand) and the wire leading from the point to the coil as the insulation was cracked and crumbling in serveral places. Also replaced the wire leading from the terminal next to where the "condenser?" connects. Replaced the kill switch as well. Re-assembled the motor. Tested with a grounded lawn mower plug. Had a bright crisp blue spark. Thought all was good. Put into a test bucket, motor fired ran 10 seconds and died. No spark. I have went thru everything with a meter and all wiring checks out. Any ideas? I don't have a clue. Thank you in advance for any assistance you can provide.

 

[Laddies]

Re: Merc 4.5 spark problems

That sounds like the insulater block on the points but here the test spec on the system from CDI 1 cyl engines use 1/2 of the system

 

[Trebor7]

Re: Merc 4.5 spark problems

Thank You Laddies,
I can add one more bit of info. The "spark" will start off bright crisp and blue then quickly fade and go away. This is happens with-in a few seconds as I spin the motor with a drill from the flywheel nut.

 

[Laddies]

Re: Merc 4.5 spark problems

The points in that engine are high voltage pts and as you build rpm the voltage grows and increases the chance for arc in the block

 

[Trebor7]

Re: Merc 4.5 spark problems

Well,
I have narrowed it down to either the module or one of the stator coils. It is my understanding that this motor uses a low and high speed stator coil. Not sure which is which. Funny this is, it still has great spark the first few revolutions then fades away. After it sits for awhile, (5 minutes) it will repeat the same proformance. Once the spark goes, it is gone no matter what rpm you spin it.
Thoughts?
Thank you Laddie for the diagram.