Auto Service Professional

OCT 2017

Magazine for the auto service professional

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Page 47 of 77

46 | ASP October 2017 Technical actuator which causes the valve piston to move upward, and the fuel injector valve return spring to push the injector valve up and seal the bored passage between the control valve chamber and the fuel return chamber, preventing any fuel to pass through. e pressure in the control valve chamber increases, causing the downward force of the control piston to overcome the upward force in the high pressure chamber, seating the nozzle needle and preventing more fuel from entering the combustion chamber. A fuel cooling system maintains fuel and turbocharger actuator temperature. e fuel system temperature is monitored by a fuel rail temperature sensor (FRT), which is an input to the PCM. e PCM commands the fuel cooler pump on by grounding the pump when the fuel or turbo actuator temperature exceeds a calibrated threshold. Coolant in the system flows from the fuel-to-coolant heat exchanger to a fuel cooler reservoir, to the turbo actuator, to the fuel cooler air-to- coolant heat exchanger, to the fuel cooler pump and back to the fuel-to-coolant heat exchanger. High pressure fuel injection pump operation After the low pressure fuel is filtered by the secondary fuel filter, it enters the high pres- sure fuel injection pump. Fuel pressure is then High pressure fuel injection pump 1. Fuel flow from secondary fuel filter to high pressure pump 2. Transfer pump 3. Inlet one-way check valve 4. High pressure pump piston 5. Outlet check valve 6. Fuel volume control valve 7. Lubrication valve 8. Gap filter 9. Low pressure fuel flow to fuel cooler 10. Fuel pressure control valve 11. High pressure fuel flow to fuel rail Art courtesy of Motologic

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