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Seems like I’ve had a few good years without issues but got one popping up again. Motor is a 2003 DF140, 530 hours, engine holder was replaced in 2016. Prior to replacing the holder was never corroded all the way through, but attempted to remove the steel plug which tore out the wall so it got replaced then.
Performed normal maintenance this spring including new plugs, oil change, anodes, impeller. Tan fine the first few times out but last two times it’s been a little more trouble to start, and has a definite miss at idle a good bit of the time. Several times I’ve had to advance the throttle in neutral at the dock to keep it running and allow it to warm up.
Once away from the dock, bring up the throttle and it will stutter and stumble until 2000-2500 RPM and then all 4 cylinders kick in and it takes off and runs great all the way to redline.
I know there are likely a dozen possible causes but short of firing the parts cannon at it I’d like to try and rule things out piece by piece. First things I’m thinking are coil and valve timing. I would not be shocked if the tappet clearances have never been checked/adjusted. I know I haven’t done it.
Here are a couple pics of the plugs which are 6 engine hours old. Clearly #2 has something going on, and looking inside the cylinder with a pen light shows a similar tale of “looks different.” But I don’t know if I might have a cylinder issue leading to poor spark, or a spark issue leading to poor combustion and thus a cylinder with extra carbon or the like. Anyway I plan to dig in more soon including taking pics with a borescope, just thought I would poke this forum for any good leads. Will update as I go.
Performed normal maintenance this spring including new plugs, oil change, anodes, impeller. Tan fine the first few times out but last two times it’s been a little more trouble to start, and has a definite miss at idle a good bit of the time. Several times I’ve had to advance the throttle in neutral at the dock to keep it running and allow it to warm up.
Once away from the dock, bring up the throttle and it will stutter and stumble until 2000-2500 RPM and then all 4 cylinders kick in and it takes off and runs great all the way to redline.
I know there are likely a dozen possible causes but short of firing the parts cannon at it I’d like to try and rule things out piece by piece. First things I’m thinking are coil and valve timing. I would not be shocked if the tappet clearances have never been checked/adjusted. I know I haven’t done it.
Here are a couple pics of the plugs which are 6 engine hours old. Clearly #2 has something going on, and looking inside the cylinder with a pen light shows a similar tale of “looks different.” But I don’t know if I might have a cylinder issue leading to poor spark, or a spark issue leading to poor combustion and thus a cylinder with extra carbon or the like. Anyway I plan to dig in more soon including taking pics with a borescope, just thought I would poke this forum for any good leads. Will update as I go.
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