The fuel line on a Husqvarna trimmer runs from the carburetor to the fuel tank. When the piston pumps up it draws air through the carburetor, sucking fuel from the tank into the mixing chamber. If this line gets plugged or clogged, fuel won't reach the carburetor and starve your engine. These lines will get dirty over time as impurities in the gas buildup along the inner walls of the rubber hose. Old gas, if left in the trimmer over winter can also dry out and leave behind a buildup that will starve your engine.
Undo the gas cap. Lift the trimmer up and pour out any fuel still inside the tank into an approved fuel container. Undo the two screws holding the air filter cover in place over the air filter. Lift the cover off and the air filter out. While you're replacing the fuel line, it's a good idea to clean the air filter.
Reach in behind the air filter's mounting box and find the fuel hose. Pinch the ending of the hose with needle-nose pliers and pull it free from the carburetor. Carefully insert a metal hook made of baling wire into the fuel tank.
Pinch the other end of the fuel line and pre-filter with the metal hook. Draw them slowly up to the tank's opening. Grab the fuel line and pull the hose and pre-filter from the tank with the needle-nose pliers.
Cut off about 8 inches of new fuel tubing. Cut one end of the tubing at a diagonal for about 1 inch. Straighten the metal wire and insert it into the opposite end of the tubing. Find the fuel line's hole next to the carburetor and push the hook and tubing through that hole. Keep pushing until the line emerges inside the tank. Withdraw the metal hook slowly.
Pull the end inside the tank up out of the tank. Leave enough tubing on the opposite end to reconnect to the carburetor. Snip the cornered end off inside the tank. Push the new pre-filter fuel filter's nozzle down inside the line in the tank. Rotate the fuel filter to make sure it is secured to the end of the line.