I am a car, truck, and diesel mechanic, but never worked on boats before. I have purchased a boat with 75 hp. Stinger Johnson. The problem I have is the top and middle cylinders have no spark. Engine runs on bottom cylider only, Cant believe it cranks at all, but does. Was told by previous owner that power pack and the 2 coils were the culprits. Would like to check out fully before just adding parts. I dont do that to my customers or to myself. Also will sometimes shock you through key when shutting down. What triggers the coils to fire? What year motor is it so I can purchase a manual? Model# J75ERLCSA Ser# J5307419. Thank you for any help you can give me.