That Tuesday last month when my engine finally ran smooth

I had been fighting a rough-running Lycoming O-320 for three weeks, chasing a stumble that would pop up around 2200 RPM. Swapped mags, changed plugs, cleaned injectors, nothing fixed it. Then a senior guy named Pete walked over and said check the fuel servo screen, not the main filter. I pulled that little screen and found it half clogged with some kind of tan gunk I still can't identify. After cleaning it and doing a ground run, the engine purred like a kitten at every power setting. Has anyone else run into a weird partial blockage that drove you nuts before finding it in a spot you almost overlooked?

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2 Comments

leo6033mo ago

Bet you just needed to run it harder to burn that gunk out.

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beth_stone3mo ago

Just needed to run it harder" - yeah, I'm not convinced that's always the fix @leo603. Sometimes gunk buildup is just carbon deposits from short trips or cheap oil, not something you can "burn out" by flooring it. I've seen people try that on older cars and end up with a check engine light or even a misfire from loose debris breaking off. Unless you're talking about a specific issue like a clogged EGR valve, I'd say it's usually more about maintenance than a good Italian tune-up.

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