Just wondering when you say  13 then 18? is that voltage or resistance & what scale on the meter? I hope you mean voltage but again what scale are you on?

I don’ know much abou the BIM ignation except it needs a component to “fire” the coil which I don’t see. It could have a threashold voltage for firing though,

Try measuring resistance from the spark plug wire, secondary winding to ground in a static mode on the x’s 1000 ohm scale for starters. I don’t know if it’s the photo but the two coils look different? Did you replace both coils or just one? I get the assumpion there is too many wires going to ground also. Can you post the diagram recieved withe replacement parts please? No capacitors too? That may be the firing component too when the cap reaches saturation it discharges to fire the coil? Not sure.

I agree Crosbyman,

Still gets it’s electrical energy from magnetiom. Seems to me it must have some kind of trigger to make the coil fire. Or cut off the energy from the primary windings to “cross” over to the secondary windings & fire the plug, Without a drawing it’s a guess at best. I have dealt with all kinds & applications with electrical but never a BIM system. In 1964 my Dad & I installed a transistor ignation on his 1964 Chevy pick up & the transistors did the switching to fire the coil.
More than likely using the same components of sort but with out a drawing I’m lost,  Guessing a SCR silicone controled recifiter or ??? Something needs to trigger it with a threashold voltage after the magnets induce a flux field.

I did some florescent lighting dimmers & we used SCR’s to slow down the switching causing the lights to dim even with full 120 volts, A guy could reverse that to fire a coil. Guessiing.I too have a 1979 Evinrude 85hp & the manual tells how to test it but how the switch box is built down to a component level. Trade  protectios??

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FKACalan