This fuel supply pump draws diesel from the tank and delivers it to the injection system at the required pressure and flow rate. It is mounted on the engine block and driven by a cam lobe or eccentric on the engine’s timing gear; the internal diaphragm or piston reciprocates to move fuel through the system. A worn pump causes hard starting, loss of power under load, or erratic idle as fuel delivery becomes inconsistent. The four-hole flange pattern matches the original mounting interface so no adapter plate is needed. On reinstallation, ensure the pump lever aligns with the cam lobe and that the gasket between the flange and the engine block is replaced.