I'm working on a 21.2 CC Echo string trimmer. It's a Zama carb. I've worked on a few of these carbs lately. But, this one is kicking me around a bit. Standard ethanol issues. After rebuilding the carb it runs...but it's very rich and won't idle completely. I can completely close both High and Low screws and it makes no difference. It runs the same way. The adjustment screws are having no effect. Starts fine. But, something's amiss.
Any thoughts? Thanks in advance.