Cummins 3629408 Fuel Block Connection OEM The Fuel Block Connection, also known as the fuel block fitting, is a vital component of a truck's fuel system. It connects the fuel line to the fuel filter housing and ensures that fuel flows smoothly through the system. Made from high-quality materials, this part is designed to withstand extreme pressure and temperature changes. A malfunctioning Fuel Block Connection can lead to decreased engine performance and even engine damage. Regular inspection and maintenance of this part are crucial for keeping your truck running smoothly on the road.