Troubleshooting '72 Mercury 110 (9.8 HP)

[GSSMITH1986]

Hi, I've got a 1972 Mercury 110 (9.8 HP) outboard with a thunderbolt ignition. This motor was laid up in my garage for about 4 years and I recently tried to restart it. It started after a couple pulls and ran rough then died and I couldn't get it to start again. It's getting fuel and compression is good but it seems to have a weak/intermittent spark. Any tips on troubleshooting the ignition?

 

[bgc]

Re: Troubleshooting '72 Mercury 110 (9.8 HP)

I found some information on CDI's web site on testing this type of ignition.

 

[GSSMITH1986]

Re: Troubleshooting '72 Mercury 110 (9.8 HP)

OK, Tested the ignition parts and the stuff is close to spec. I found lots of rotten wire. Insulation falling off everywhere it touches anything. Question: Can I build new ignition wires (from points to coil and from ground and ground switch) from West Marine wiring components or is this wire some sort of special ignition stuff?

Also, the insulator block to the points fell apart too so I'm going to replace them as well.

 

[bgc]

Re: Troubleshooting '72 Mercury 110 (9.8 HP)

Insulator block failure is common.
I dont see why you couldn't make your own wires.

 

[GSSMITH1986]

Re: Troubleshooting '72 Mercury 110 (9.8 HP)

Victory! Hot spark in both cylinders. Replaced all the ignition side wires and the insulator blocks, cleaned the points and regapped to 0.020 and #2 cylinder had bright blue spark, but nothing in #1...I then checked spark plug wire and DOHHH! it was not seated in coil. Reseated it and yanked again...boom bright blue in both. Now I'm a little embarrassed. I retired this motor 6 months ago...gave up on it, and bought a new nissan 9.8 4 stroke but hated to throw this motor away. Now I've two 9.8 HP motors.

Moral of the story...don't give up and check/reconnect all your wires before you move on. Not sure what I'm gonna do with it now. I expect it will fire right up tomorrow.

 

[Mi duckdown]

Re: Troubleshooting '72 Mercury 110 (9.8 HP)

I'll bet will outrun that 4 stroke. but will smoke more when trolling.???

 

[bgc]

Re: Troubleshooting '72 Mercury 110 (9.8 HP)

Mount both on transom, Duel 9.8's