The fuel lines on every Stihl engine contain a main or suction hose and an impulse or return hose. These hoses suck gas from the tank into the carburetor and any excess fuel returns back to the tank to be reused. The lines age quickly due to fuel impurities and must be replaced almost every season. Clogged or dirty fuel lines are also the cause of many common engine problems. Replacing these lines will help ensure that your engine runs smoothly.
Things You'll Need
Approved fuel container
Metal hook (baling wire)
Stihl press fluid
New fuel filter
Open the fuel tank cap. Drain all old fuel back into an approved fuel container. Pull the fuel filter at the bottom of the tank upward using the metal hook. Pull the fuel filter off the end of the suction hose.
Remove the air filter's cover. Unhook the air filter. Remove the two mounting screws holding the air filter box in place. Remove the choke cover plate on top of the carburetor. Unhook the throttle cable from the choke cover plate.
Pull the fuel return hose off the stub next to the spacer flange using your fingers. Pull the fuel suction hose out of its seat on the carburetor. Pull both lines out of the engine and throw them away.
Cut off two lengths of fuel tubing about 6 inches in length. Slice a 45-degree taper into one end on both lines. Unbend the hook in the metal wire and insert the wire into the suction hose. Push the hook and suction hose through the main fuel hole in the fuel tank.
Withdraw the metal wire. Coat the grommet on the new suction hose with the Stihl press fluid. Push the fuel suction hose down until the rubber lip is properly seated and the flange on the hose lies flat against the fuel tank.
Coat the stub and end of the return hose with Stihl press fluid. Push the return hose until it stops against the stub. Coat the other end of the return hose and the suction hose with Stihl press fluid. Connect the suction hose to the intake valve on the carburetor. Connect the return hose to the outtake valve on the carburetor. Make sure both hoses are properly secured against their respective valves.
Pull the main fuel line up into the tank opening use the metal hook. Push the new fuel filter's nozzle firmly into the suction hose. Refit gas cap, air filter box, air filter and filter cover before reusing the Stihl.