17721-ZY3-000 Fuel Return Joint - Overview. The 17721-ZY3-000 Fuel Return Joint is a critical component within Honda marine engine fuel systems. This OEM part connects the fuel return line, facilitating proper fuel circulation and system management essential for reliable engine function. Designed to meet exact factory specifications, the joint guarantees seamless integration with other fuel system components, helping to maintain optimal engine performance and durability over time.. Key Features.