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'96 Yamaha 25HP 2stroke - Backfiring/lean sneeze?
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<blockquote data-quote="marlin3030" data-source="post: 366486" data-attributes="member: 13659"><p>I just bought a boat that has a 25hp Yamaha. it's a pull start and starts super easy but no matter what rpm it has a slight backfire. It never dies but the "cough" doesn't get better as rpm's increase. So far i've changed the spark plugs, and cleaned both carbs. I even tried seeing if i had an issue with one of the ignition coils. I can pull the plug wire off the top cylinder and it dies. I can pull the plug wire on the bottom cylinder and it keeps running on one cylinder no problem. I switched the coils and it's that same way. So i think i've narrowed the problem down to the bottom cylinder but i don't know where to go from here. I haven't tried adjusting the idle screws yet, but i might give that a try tomorrow since it sounds more like a lean sneeze. The only other thing i can think of is the CDI unit. What are the chances that the CDI unit is starting to go out? Thanks in advance!</p></blockquote><p></p>
[QUOTE="marlin3030, post: 366486, member: 13659"] I just bought a boat that has a 25hp Yamaha. it's a pull start and starts super easy but no matter what rpm it has a slight backfire. It never dies but the "cough" doesn't get better as rpm's increase. So far i've changed the spark plugs, and cleaned both carbs. I even tried seeing if i had an issue with one of the ignition coils. I can pull the plug wire off the top cylinder and it dies. I can pull the plug wire on the bottom cylinder and it keeps running on one cylinder no problem. I switched the coils and it's that same way. So i think i've narrowed the problem down to the bottom cylinder but i don't know where to go from here. I haven't tried adjusting the idle screws yet, but i might give that a try tomorrow since it sounds more like a lean sneeze. The only other thing i can think of is the CDI unit. What are the chances that the CDI unit is starting to go out? Thanks in advance! [/QUOTE]
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'96 Yamaha 25HP 2stroke - Backfiring/lean sneeze?
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