The purpose of the Fuel Line is to allow gas to flow from the fuel tank to the engine. Over time, damage from heat, wear, debris in the tank, and chemicals can cause the fuel line leak or become brittle and crack. The length of the line varies based on the equipment. Bulk line is often sold by the inch, so you'll want to measure the old line to ensure the replacement will fit correctly. For easier installation of a carburetor fuel line, add some oil to the end of the line to help it slide.