66' Mercury 3.9 hp no spark.

[thx997303]

Okay, so this motor has no spark.

What kind of ignition do these run and where should I start diagnosing the issue?

I unfortunately, do not have a manual.

 

[thx997303]

Re: 66' Mercury 3.9 hp no spark.

Really? Somebody has to know this stuff.

 

[Chinewalker]

Re: 66' Mercury 3.9 hp no spark.

Your motor has a magneto - coil, points and condenser, with a magnet in the flywheel.

The age of your motor tells me the coils is probably okay - they had their stuff together by that point with the Phelon coils. If it doesn't show any evidence of cracking or arcing, it's probably good. The condensers are generally the weak point. You should be able to get a new one at a Merc dealer. Good idea to replace the points while you're at it. Check the spark plug wire for cracking, too.

 

[thx997303]

Re: 66' Mercury 3.9 hp no spark.

Hope the coil is okay. Dang thing is expensive.

I was looking at some parts diagrams and they seemed to say this thing had a distributor.

Course, why would you need a distributor for a single piston engine? Thought it was weird.

You wouldn't be able to tell me the flywheel torque spec for this thing would you?