Fuel lines that are exposed to direct sunlight have a limited lifespan, and after five or six years, they crack or leak. Sure, it's tempting to cut out the offending section and barb-and-clamp the line back together. But once one crack appears, more are sure to follow. Considering how dangerous a fuel leak can be, it's not worth messing with. Buy a new hose. If you have an outboard, replace the entire assembly. Why fix one piece of it, when you know the rest is as aged as the section that went bad?