I have a 2-stroke 30 HP 2 cylinder Mercury mid 90’s model on my Jon boat. Took the boat out last week and the motor was struggling under load, could not get it on plane. Turned around and went back to dock, fuel line had been crimped when I hopped in the boat at the dock and though it was perhaps collapsing. Fixed fuel line and tried again, ran good for a few minutes then back to the same thing. Pulled fuel filter and emptied, looked pretty cloudy so replaced fuel filter and fuel in portable tank. Ran again and still same issue, pulled and cleaned the carb, still same issue. Replaced bulb still same thing. Sounds like only running on 1 cylinder, pulled pug wire off top cylinder, would not crank. Replaced and pulled wire from bottom cylinder and motor starts and runs just like described above. Figured coil was bad on bottom cylinder, used a tester and tester light shows spark on both top and bottom cylinder? (Tester goes between plug and coil and lights up to show there is fire) Pulled plug and plug looked fine. Cleaned to be on the safe side, but still same issue. Have not replaced plug yet, do plugs actually go totally bad? Or is there more than likely another issue that I am missing?
Only one carborator on motor, since upper cylinder is firing and running I know I have fuel making it there so is it safe to assume fuel is making it to lower cylinder as well? Going to try new plugs as well as they most likely need to be replaced anyway. Don’t have a way to check compresson so if plugs don’t do it I may be headed to shop with it. Unless someone has other ideas?
Wow, never had this happen before, spark plug was bad. Installed new plugs and running like a champ. Never knew they went totally just thought performance deteriorated over time. Wonder if the bad fuel impacted the plug? Regardless $5 at Advanced Auto and back up!
had a plug die on a 150 johnson few weeks ago. they def go bad.