Been working off and on since last year on an Echo SRM-225 string trimmer (weed eater) that decided last year to refuse to run at any throttle above an idle. Carb kit and replacement carb, crank seals and nothing changed.
Cutting out many blw-by-blows discovered TODAY these carbs are NOT fixed mixture! They have cleverly hidden high and low speed mixture screws! The replacement carb had the high speed completly closed and the original carb has the ethanol high speed circuit blocked!
Found the basic setting for idle is four turns out from closed and high is the standard 2-2.5 turns. Tweeking after idle has returned this excellent two smoker to service.
Never turn down a couple of hours watching youtube how to vlogs for answers!