Originally Posted by McDowell Racing
Before you spend too much on ignition parts, pull the carb and tank unit off and seperate the carb from the tank. Between them is a gasket and diaphragm. Mine had a sucked in spot and was doing exactly as you said, engine speed hunting like the governor was sticking, puffing black smoke every now and then and having to fill up 3-4 times more often then normal. It cost me about $3-4 plus shipping from Jacks Small Engines on the net. The alcohol in the gas caused the diaphagm to fail I'm almost sure.
I had the edger running yesterday, but it quit 3 x's and in frustration I broke down and took both to a small engine shop. Not surprisingly, the guy said the same exact thing, the E10 gas trashes the gaskets. He wasn't sure about the spark issue, said that a new coil (if needed) would prolly not be worth doing but he might have some used parts that would fit...