I have outboards come through the shop fairly often that have gummed up carburetors. The owner tries an additive in the gas, then goes out and runs up and down the lake in an attempt to clean the carburetor, that has plugged or restricted passages. Since all fuel must pass through the high speed jet, (along with the lubricating oil!) then up through the main well and through the low speed jet, (even smaller in size) the owner ends up with a scored cylinder, and ruins the power head. Of course, I always check the compression first, and if low, I take a gas sample. I’ve learned to spot the ”look” of certain additives in fuel, and often times I find out that the customer tried 2 cans of magic additive, thinking he can really fix it quick. Since I own and operate a marine repair shop, I’ve seen a lot of this sort of thing. Lots of engines have been running for years with proper maintenance and care, and without magic additives. Nothing beats a good carb overhaul and cleaning.. Just my humble opinion, respectfully
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