Faulty fuel mixture can be:
no two-stroke oil in the fuel
too old fuel
wrong fuel type
wrong ratio between fuel and two-stroke oil
1.
Remove the cover and once it is off, remove the spark arrestor. Spark arrestor is located on the front of the muffler with a cover.
2.
When inspecting it, make sure the spark arrestor is intact and there are no rips and holes in it. Also, make sure there is no excessive carbon build-up. If there is any carbon build-up it will make your brushcutter run at a lower RPM and the products will not breath very well.
3.
Clean the carbon build-up from the spark arrestor with the wire brush.
Once the spark arrestor is clean, put it back in place.
Husqvarna recommends that after every 50 hours of operation, the spark arrestor is cleaned.