no spark on top plug

[titan232]

Hello everyone. I have a 1970 Evinrude Sportwin 9.5 that ran great for the last two seasons. At the end of last season it was running fine one day and the next I had trouble starting it and when it did run it had very little power. I changed the plugs which didn't work and when I pulled the plugs, one was fouled and the other looked fine. I tested for spark on both plugs and the plug for the top cylinder has no spark. I'm assumming a bad coil or wire. What should be my next step? 'How easy is it to change a coil in this motor? I know nothing about pulling the flywheel to access the coils. Any way of determining if it is in fact a bad coil?

 

[DJ]

Re: no spark on top plug

You can just about bet that a coil has failed. The old (original) OMC coils had a habit of the outer casing cracking, thus the coil failed.

Pulling the flywheel is not hard or easy, to a novice.

1. You will need a harmonic balancer puller. They're available at places like Harbor Freight Tools, pretty cheap.

2. You will need a stap wrench to hold the flywheel. Again, pretty cheap.

3. You will need the proper size bolts (3) to thread into the flywheel. Make sure not to screw them in too deep. DO NOT ATTEMPT TO PULL FROM THE OUTER EDGES OF THE FLYWHEEL.

4. Remove the flywheel nut (strap wrench).

5. Secure the puller on the flywheel. Tighten down the center mandril until she "pops". A little PB Blaster penetrating oil will help here. DO NOT over tighten the mandril.

6. Once inside, it's pretty straight forward.