Make sure the chain can be turned by hand and is well oiled. Check the muffler, fuel filter, and air cleaner for plugging. Check the condition of the fuel lines and primer button--does the primer pull fresh fuel into it when pumped? Check the carburetor fasteners for tightness including the mounting to the cylinder. If there is a rubber isolator between the carburetor and cylinder, check it for cracking or any holes. Make sure you are using modern synthetic saw oil in the fuel, not boat motor petroleum based oil. If still acting up, clean and re-kit the carburetor. Hope this helps!