Corvairdave
New member
Newbie here. I have a '97 25hp merc outboard. Bottom cylinder runs well, top has very intermittent spark. Here's what I know; 120psi compression on both cylinders, coil packs, spark plugs, spark plug leads, CDI box all good. Bad spark follows coil lead for top cylinder. Pulling top lead when running makes slight difference, pulling bottom one kills it. I disconnected the kill switch wire last night and it made no difference. I'm going to clean up every ground on it, but it seems I'm missing something. I'm a decent mechanic, but have no outboard experience. Would love some help-suggestions! Cheers, Dave