stihl weedeater fs56rc weird engine problem (2024)

Hi all, new to the forum. I have a 10 year old Stihl fs56rc weedeater that recently will not get to a high enough rpm to move the trimmer head fast enough to cut. We just moved to a new house this fall and in the hustle of this i forgot and didn't winterize/drain gas SO i assumed it was the carb sitting with gas in it (which had happened once about five years back and was fixed by replacing carb) so this time around I replaced the carb (genuine stihl) and the spark plug and is the same issue! it will idle but when you give it gas it will not rev up enough and sounds like its bogging down and it dies easily. I replaced the air filter and the fuel screen inside tank is clean. NO IDEA, is this a sign that this has reached its life expectancy or something simple I'm missing? Don't know what else it could be, fuel flows fine to primer. thanks in advance

Remove the muffler and see if the screen is plugged up partaly . Mine did this and would rev up for about 30 seconds this slow down to a idle. I just left out the screen and then it ran so fast I did not feel comfortable with it and cleaned the screen and replaced it , it must act as a RPM governor and spark arrestor .

ahh, awesome idea, reminds me of a two stroke dirtbike i had that bogged bad, had carbon build up bad in expansion chamber and muffler. thanks!!

Most of the Stihl brand trimmers have a removeable screen outlet that has a round hole. 15 MM deep well socket to unscrew it and then use a torch to burn the residue loose and then a wire brush to clean the carbon.

Thanks all. this is exactly what it was, almost completely obstructed. Runs like new now, crazy how the piston still looked new when taking the muffler off, and i thought this thing was end of life haha. Its scary strong now. ONE MORE PROBLEM though, after putting the plastics back together and cranking it, now the darn kill switch wont work, i checked the connector at the button side and they are still connected, so where does the wire go? it must have pulled loose when i pulled it apart to get to muffler, ughhhh

Here is a pic of both.

Thanks so much, found it was the wire goin to the carb, was loose somehow. Everything runs like new now, man what a difference. i guess over time the carbon build up kept getting worse and worse but now its super strong. Thank you all immensely!

You guys/gals are great. Does anyone have any tricks or at least the precise location one of (I think two) metal return springs for the throttle release or throttle. I'm not sure which because when I was fighting to reassemble and attach the motor section to the shaft section it popped of from where ever. I'm just lucky I noticed it on the ground. It's a Stihl FS56. I see someone else fought with the wires right there./\