No Spark - 1967 Mercury 110

[AlexReitenND]

I recently purchased a 1967 Mercury 110 9.8hp for $45; it has good compression (115 on both cylinders) and looks pretty clean under the cover. My problem is that I can't get it to spark. The first thing I did was disconnect the kill switch because the wires were falling apart. After taking off the kill switch I was left with two wires that come from each of the points I wasn't sure if they were supposed to be grounded or not, but I tried it both ways and still no spark. I pulled the flywheel and checked the points; they looked clean, but I reset the gap and polished them anyway. Next, using a multi meter I tested the continuity of the points and found that they form a complete circuit when both open and closed. Trying to figure out what they grounded to I disconnected all the wires coming out and found that when the coil is connected the points are continuously grounded and when the coil is disconnected they only ground when closed. This is where I'm stuck; are the points supposed to ground through the coil when open? What else can I try? I'm having trouble finding alot of info on pre 70's mercs ignition systems, so any ideas are appreciated.

 

[RCO]

The points will have continuity to ground through the coils and condensers even when open. The condensers are probably shot, you can test them for capacitance if your meter has that function. The reading should be around .2 uf IIRC. The kill switch connects the two sets of points together to stop the motor. Magneto ignitions do not need any external ground to fire.

 

[Chinewalker]

My money is on the condensers - common failure on those Phelon magnetos.