77 Johnson 6hp no spark below 3/4 throttle

[Rodman738]

Just picked up this 77 Johnson 6hp. Motor is clean the guy I purchased it from said it was running fine!!
coils plugs cdi box all look new.
Motor only will run from 3/4 to full throttle! When you back the throttle a little bit it loses spark in both cylinders.
i had another cdi box I switched out with no difference. I'm thinking the trigger under the flywheel? Or the coil under flywheel? Don't really understand what kills motor as there is no kill switch. Anyone ever had this issue?

 

[jimmbo]

Or wires making Intermittent contact or grounding when Ignition Plate rotates

 

[oldboat1]

^^agree. Check for abrasion(s).

 

[F_R]

X3. Wire broken internally from constant bending back and forth every time throttle moves.

 

[Rodman738]

Will take a close look at wires!! What kills the ignition on these? No kill button ?

 

[jimmbo]

Engine is usually stopped by retarding the Throttle till it dies, if there is an Idle stop preventing that, pull the choke

 

[Crosbyman]

broken wires

measure the resistance for a constant 4-7 Kohms from boot to frame while rotating the mag plate with the throttle

 

[Rodman738]

Thanks for the great advice!! Finally picked up a multimeter today had a wire to the trigger that only made intermittent contact. Replaced the wire and now she purrs like a kitten!! Thanks again for for the great advice! Great to see people sharing there expertise with others. Hope I can share a little advice sometime !