I need to see how the trigger is installed in weedeater

https://video.search.yahoo.com/search/video?fr=mcafee&ei=UTF-8&p=ryobi+31c+weedeater+will+not+idle&type=E211US1494G0#id=1&vid=3a28cd20d10b0a98f6fa51d97cea0dfc&action=click
This site will show you how to adjust the carb idle.

copy and paste

https://www.diyspareparts.com/parts/stihl/diagrams/fs-40/53a81903-6c7f-4412-96d1/


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Check the throttle cable connection at the carburetor throttle linkage, it (cable) may be broken or the carburetor linkage is broke.

Not all are the same,need model #.

Husqvarna 128 ld weedeater only runs when spark detector is hooked up. Otherwise it dies.

hope this helps. http://www.ereplacementparts.com/weed-eater-xt200-type-gas-trimmer-parts-c-17589_17626_18184.html

remove the muffler and try it if ok open the muffler and clean out the carbon from the screen

120' cord. I would go to a big-box store and investigate making your own cord so that you only have 2 ends. 12 guage at the very least. any thing smaller, and you will burn up the motor.

I believe that the trigger and throttle cable should solve your issue.
530071550 throttle kit $8.16 + 12.75 shipping

I’m happy to assist further over the phone at https://www.6ya.com/expert/rolandw_c013176d62ee17ae

manddmower.com
part # will be 530038682

try this get a good extension cord test it plug it in now with the trigger pulled wiggle the cord going into the weeder i have in the past moved the cord till i got working and taped it to the handle, if that dosent work get a new one