This fuel filter element removes particulate and water from the fuel supply before it reaches the injection pump. It mounts in the fuel line between the tank and the primary pump, where it protects the precision clearances of the injector nozzles and pump plungers from abrasive contamination. A restricted element reduces fuel flow, causing hard starting and power loss under load. The manufacturer machines the sealing surfaces to match the filter head, ensuring the bypass valve seats correctly and no unfiltered fuel bypasses the element. Replace the sealing gasket on reinstall and tighten the housing to the specified torque.