Re: 20 hp no spark
Bushkey,
I, just last night, discovered my power pack is dead. Let me tell you how we troubleshot it. (BTW, I've got an 1985 XD 18). I had the motor running and thought all was well and then removed the lower plug wire while it was running....low and behold, no change in engine performance. Pulled top wire off and engine wouldn't start. I've been running on one cylinder. My motor would run and was intermittently running great, but in general very sluggish. I knew my top plug was firing so we used it as the test plug. Removed both plugs and popped the known good plug into the known good wire and pulled. Got spark. Put that plug in the known non firing wire and sure enough no spark. Switched the positive wires going to each of the coils to test for a bad coil. Problem moved to the other coil. (This indicated that both of my coils were working and that they were not the problem)
This led me to believe that my power pack was bad, but just to make sure, we switched the leads coming from the stator and the trigger. (This was sort of tricky because they idiot proof the connectors. But with a little solid strand copper, it was easy to bypass.) Problem stayed the same. So we know that the stator and the trigger wasn't causing the problem. (Now if anyone questions the validity of this part about the stator and the trigger...I'm open to criticism, but I wanted to make damn sure before I threw down $89 for a new power pack)
Here's where I can offer you a suggestion. Do NOT think that you can outsmart Mercury and try to dig out the electronics from the power pack. Figuring that "it's already broken...how can we go wrong", we began digging the rubber out from the back using a heated wood carving knife. We finally got all of the rubber off of the back of the circuit card, only to realize that now the front of the circuit card is emersed in rubber. Needless to say, Mercury didn't want folks like me/you to repair these modules. (Hence the ridiculous asking price for them) Something else of note, those modules are far more complex than the diagrams lead you to believe. The diagram i saw only showed 2 switches, 2 diodes and 1 cap. There were alot of components on that circuit board I tore up.
Anyway, I hope that gives you some direction. I used no special test equipment other than a regular old multimeter set to AC volts on the + terminal of the coil. When pulled, I was getting a decent amount of voltage on my good coil. I don't recall actual voltage reading, but it was very quick and I just figured that if it it's getting voltage the other one isn't...question answered.
Mark
