This fuel supply pump delivers diesel from the tank to the injection system at the pressure and flow rate required for engine operation. It mounts on the engine block and is driven by the camshaft or an intermediate gear; the pump's internal mechanism draws fuel through the supply line and pushes it through the filter to the high-pressure injection pump. A failing pump typically causes hard starting, loss of power under load, or engine stall due to insufficient fuel delivery. The manufacturer machines the pump body and internal components to match the original assembly's mounting flange geometry and drive engagement, so no adapter brackets or shims are needed for installation.