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1972 9.8 hp 110 Ingnition Module wiring

K

Ky Howard

Contributing Member
I have a SN 3448852 and appears to be about a 1972 model. I removed the module in order to replace one of the coils, marking where each wire went then found I forgot where one wire went. It's the wire that goes to the case ground screw in the lower housing. I've checked numerous sites for 110 wiring diagrams but most either show a system with a stator type ignition or don't show that wire clearly.

This model has dual points with two small coils under a red plastic module that is potted on the bottom. Can anyone tell me where the wire to case ground goes? I'm thinking on the module, innermost terminal on the opposite end from where the coils connect, but I'm not sure because there doesn't seem to be enough room.

Any help would be appreciated
 
Doesn't matter long as it grounds out.

The kill switch works assbackwards on these: it opens the circuit to kill the motor, If that switch doesn't ground out you have no spark.

Jeff
 
Thank you fastjeff. I wasn't clear in my question. I have the location of the case ground. It's a screw on the lower housing. I was wondering which terminal on the red plastic module that wire from the case ground goes to?
 
The ground comes off the metal base the points are mounted on. Any good ground will do.

Jeff

PS: This is the infamous Phase Maker system that sends 300 volts to maker (not breaker) points to fire the coils. Electronic switches now do this job much better. A common failure point on these is those plastic blocks in the points assembly that develop minute cracks and short to ground.
 
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thanks again, I will attach that case ground to one of the condenser hold down screws. As for the plastic blocks, I didn't care for them when I took it apart so I replaced them.
 
fastjeff, I got it back together last night. Did you know that when you have the coils hooked up wrong, i.e.coil 1 firing when it should be coil two, the explosion created by the exhaust being wide open creates an ear shattering bang in your 5 gallon bucket (tank) LOL...a quick swap and the motor started almost immediately and ran like a top!
 
Great! Those are excellent little (unappreciated) Mercs.

One caution: Do NOT shut the motor off with the kill switch--that causes damage to the ignition system. Use the choke or set the idle too low so it will stall. Important! The singe cylinder Mercs (3.5 and 4 hp) did not have a kill switch and their ignitions lasted forever.

Jeff
 
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