1971 9.8 Spark only at WOT

[hosser]

1971 mercury 9.8 no spark on either plug,only in forward gear ,new coils new stator ,wires .when trottle handle is in netural no spark, forward gear lots of spark whats up with this?

 

[achris]

Hello hosser and :welcome: to iboats.

I've move your posts to a new thread, as the one you tagged onto was over 3 years old. (we try not to disturbed the sleeping threads )

As I said in the thread you tagged onto, the only things common between both cylinders for spark are the stator and the stop button, and as you can get spark when you go to WOT, then that pretty much rules out the stator. The stop button must be CLOSED for the spark to be produced. As the problem appears to be ignition contacts (points) housing relative, don't rule out a short or open wire... Check all the wires for continuity and insulation/isolation...

Chris.......

 

[jimmbo]

As mentioned a wire(s) is/are shorting or opening as the throttle is closed and the timing plate retards
That engine is almost 47 years old. In those days mercury was using wire with an insulation that hardened with time, cracked, allowing shorts to occur, and in the longer term wire breakage. Quite common on Mercurys of that era and older

 

[hosser]

new wire from points .STUMPED

 

[jimmbo]

Inspect the points for shirts to ground, That's a 1971, They used a CD ignition system they called PhaseMaker. Unlike a conventional ignition system, where opening the points generates a spark, this system had the spark created when the points closed

http://www.boatinfo.no/lib/mercury/m...2-40.html#/134

 

[hosser]

so should I gap the points when they are on high cam or of hi cam?

 

[achris]

Points gap is maximum gap, so gap them when the gap is at its widest, usually at the high point of the cam.