This solenoid controls the flow of fuel or hydraulic fluid in the engine system. It mounts directly to the injection pump or valve body and receives an electrical signal to open or close the circuit. When the coil is energized, it shifts the internal plunger, which actuates the connected mechanical linkage. A failing solenoid may cause intermittent starting, stalling, or a no-crank condition because the plunger can stick or the coil can short. The manufacturer machines the plunger and bore to the same clearance as the original assembly, ensuring the magnetic field pulls the plunger fully without binding. On reinstallation, verify the electrical connector is clean and seated fully to avoid voltage drop.