How to troubleshoot your Husqvarna line trimmer when it runs rough
If the fuel has been in the tank unused for months, it can pick up moisture and fail to ignite (that's why you should drain the fuel before storing for the winter or add fuel stabilizer to the tank). Replace the fuel with fresh gas if it's old and untreated with stabilizer. You might also need to replace the fuel filter at the same time. Performing preventive maintenance including a line trimmer tune-up will also help the engine run smoothly.
Check the fuel lines for cracks and replace them if necessary. If you still have problems after checking those issues, consider replacing or rebuilding the carburetor.
How to maintain your Husqvarna line trimmer
Because your Husqvarna grass line trimmer is a relatively simple tool, you might forget that it needs routine maintenance just like your other lawn tools. Taking a few basic steps goes a long way toward keeping your trimmer ready.
At the start of each season, put fresh fuel into a gas-powered trimmer and check the cords on an electric trimmer. Replace the trimmer line, too. Old line can become brittle and break easily.
Before each use, fill the tank with the gas/oil mix recommended in the owner's manual; 40 parts unleaded gasoline to one part 2-cycle engine oil is typical. If you have an electric trimmer, check the power cord. Make sure you have plenty of replacement trimmer line on hand. If you're using a blade, inspect it carefully and replace it if it's bent or broken.
Before you put your trimmer away for the season, give it a thorough cleaning and lightly oil the metal surfaces to prevent rust.