93 mercury sport jet intermittent spark.. Help!!

[n3srj]

Been reading the posts on here for a month now. Great information great users. Here is my problem. On the top cylinder I have intermittent spark. Spark there when engine cranks.. Disappears when the engine is running.

What I have done so far.

Switched top coil to middle plug.switched terminals on the switch box. Get spark from coil constant. Ruled out coil. Stator appears to be replaced. (engine runs fine and starts up instantly on 2 cylinders). disconnected wire for ignition/rev limiter no change.

Is it the trigger/switch ??? I'm at wits end at this point. Any help is appreciated .

Thanks

 

[n3srj]

Re: 93 mercury sport jet intermittent spark.. Help!!

I guess this is a problem that's never happened to anyone. Kinda quiet in here

 

[pnwboat]

Re: 93 mercury sport jet intermittent spark.. Help!!

If you have the Mercury Thunderbolt ignition system that uses black coils and a switchbox, look up underneath the flywheel and make sure all six magnets are intact and not loose or missing.

 

[n3srj]

Re: 93 mercury sport jet intermittent spark.. Help!!

magnets are intact. got my new switch yesterday. Installed it and turned it over. again spark at #1 top cylinder then once engine catches (runs on 2 and 3) the spark mysteriously still disapears?? Can't figure out why after the motor starts (other than crank rpm vs idel rpm) why does the spark disapear. Guess i'll pull the flywheel and replace the trigger next?
I'm faily certain the replacemnt CDI stator is ok as starting and running on 2 cylinders is not a problem. Motor fires right up!

I've pulled the yellow/black wire off of the switch which from my repair book and what i've read on line should eliminate the rev limiter diasableing spark but it reamined the same with the wire disconnected. everything points to the rev limiter though.

Completly at a loss other than keep throwing parts at this beastie. Who ever invented this setup had to be smoking their lunch!!