Remove the spark plug wire from the end of the spark plug.
Remove the Poulan's gas cap by twisting it to the left.
Insert one end of the siphon hose into the trimmer's gas tank and squeeze the handle to siphon the gas from the trimmer tank to the gas can.
Use a Phillips screwdriver to remove the plastic air filter cover. Remove the fuel line from the bottom of the old gas tank after the cover is removed and the tank is accessed.
Use a screwdriver to remove the clamp holding the old fuel tank in place, remove the old tank and then set the new one in place. Replace the clamp and the retaining screw.
Insert the new fuel line onto the port at the bottom of the new gas tank.
Fill the new gas tank with the gasoline-oil mixture and place the cap on.