Hey Everyone I have a 70 HP Johnson 1975 year been losing spark to number one cylinder then regaining it . I have a timing light hooked up to it that's how I noticed it . haven't tried swaping coils yet I'm waiting for my manual to come first before I do that anyways I wanted to test my killswitch to make sure that isn't the issue, has awesome spark when I air gap tested it . Even ran it with pulling plugs out of cylinders to diagnose it with the murder on . I see A black and yellow wire on my power pack and also one that appears to be in a wiring terminal block, do I disconnect all black and yellow wires and test for spark on that cylinder to make sure I have constant spark to it? Also if I disconnect my wires will I be able to shut the engine off while running? Haven't really found a set by step thread on this forum to test killswitch. Waiting to get the manual before I really rip into the electronics more. Also I have new plugs carbs were professionally gone through cleaned not rebuilt and has new gas I run 91 octane with no ethanal additives and mixing 50:1 ratio 16 ounces I beleive to every 6 gallons of fuel I know forsure #2 coil was replaced before I bought it. My boat has a studder to it at about half throttle I'm thinkin that's where I'm losing spark then regaining it after half throttle. I'm leaning towards a power pack issue or coil.BUT I want to test all my systems to make sure everything is aye ok! Also I'm going to look for loose or cracked wires and clean my grounds where I can see them any info would help thanks!
