How do I know which fuel line goes where on a stihl fs 85 pro?

To identify which fuel line goes where on a Stihl FS 85 Pro, refer to the owner's manual for a detailed diagram of the fuel system. Generally, the larger fuel line connects to the fuel tank and the smaller line goes from the carburetor to the fuel filter. If you don't have the manual, you can also find diagrams online or consult a small engine repair shop for assistance. Ensure the lines are securely connected to avoid fuel leaks.