Only runs smooth under load

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Only runs smooth under load

Postby MNFarmall » Tue Jun 04, 2019 9:43 am

For those of you who saw my last post, you would know was able to solve my coolant leak issue with thread sealant and copper coat. As is tradition, a new problem has been identified now that it starts and runs. After performing all of the other tuneup tasks that are recommended, the Cub starts faster and easier than ever. However, I notice it sporadically misfires, regardless if it's just after starting or after it has warmed up. The peculiar thing to me is that when under a load it purrs like a kitten, and there doesn't seem to be any significant power loss. I recently acquired and restored the cultivator for it (will post pics soon), and was eager to try it out. When driving to the garden it randomly misfires, but as soon as I put the sweeps in the ground it runs like a top, with not a single misfire.

It doesn't bother me terribly since it works just fine when it's doing dirt work, but it is annoying to hear it "puff" when driving it around. Any ideas?

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Re: Only runs smooth under load

Postby Don McCombs » Tue Jun 04, 2019 10:04 am

Intermittently sticking valve? Add some Seafoam to the fuel and oil per the directions on the can. Then, do some more cultivating.
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Re: Only runs smooth under load

Postby Urbish » Tue Jun 04, 2019 10:32 am

Have you checked for vacuum leaks?

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Re: Only runs smooth under load

Postby outdoors4evr » Tue Jun 04, 2019 12:07 pm

Maybe a little lean on the idle circuit? Turn in the idle air valve a tad. (Turn in = richen the fuel to air mixture)
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Re: Only runs smooth under load

Postby Waif » Tue Jun 04, 2019 3:23 pm

Something to consider if leisure time offers...

You could shut your Cub off when it is and has been working hard . Without reducing it to idle and cooling off.( Not something I would recommend normally.)
Pull a spark plug and study the deposits and color.

Some reading about plugs.

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