The Z 17 DTH engine is fitted with the HP 3 high-pressure pump from Denso.
The task of the high-pressure pump is to draw in fuel and make available the required system pressure in the pressure accumulator.
The admission pressure that the high-pressure pump requires to operate is provided by the mechanical delivery pump incorporated into the housing of the high-pressure pump.
The high-pressure pump works as a twin-acting plunger pump. It is the interface between the low-pressure side and the high-pressure side. It continually generates the system pressure for the pressure accumulator.
The high-pressure pump is mounted rearwards on the timing case and driven by the camshaft toothed belt.
- 1. High-pressure pump
• Service: The Common Rail system of the Z 17 DTH engine does not need to be bled after installation work. It is self-bleeding. To prevent the starter from overheating, the bleed process must only be carried out by actuating the starter continuously for 40 seconds maximum. After that, a sufficient amount of time must elapse to enable the starter to cool. The bleed process can be repeated if required.
Diagram of Fuel Flow
- 1. Injectors
- 2. Pressure accumulator
- 3. Pressure limiter
- 4. Fuel temperature sensor
- 5. Metering unit
- 6. High-pressure pump
- 7. Fuel tank
- 8. Fuel filter
- 9. Engine control unit
- 10. Fuel pressure sensor
Diagram of High-Pressure Pump
- Side view
- Rear view
- 1. Eccentric shaft
- 2. Shaft seal ring
- 3. Polygonal ring
- 4. Pump plunger
- 5. Pump valve
- 6. Fuel feed system
- 7. Fuel return system
- 8. Delivery pump
- 9. High-pressure pipe
- 10. Fuel temperature sensor
- 11. High-pressure connection
- 12. Metering unit
Functional Diagram of the High-Pressure Pump
- 1. Metering unit
- 2. Polygonal ring
- 3. Valve - intake side
- 4. Valve - delivery side
- 5. Pump plunger
- 6. High fuel pressure
- 7. Eccentric shaft
- 8. Pump plunger
- 9. Valve - delivery side
- 10. Valve - intake side
- 11. Fuel feed
Diagram of Pump Element
- 1. Pump element
- 2. Pump plunger
- 3. Valve - intake side
- 4. Valve - high-pressure side
- 5. Holder - high-pressure pipe
- 6. Spring - pump plunger
Metering Unit
The metering unit regulates the system pressure in the pressure accumulator by limiting the quantity of fuel in the high-pressure pump. The metering unit is incorporated into the high-pressure pump and is actuated by the engine control unit.
Diagram of metering unit
- Metering unit, not actuated, low delivery quantity
- Metering unit, actuated, high delivery quantity
- 1. High-pressure pump
- 2. Holder - high-pressure pipe
- 3. Delivery pump
- 4. Pressure regulating valve, pre-supply pump
- 5. Metering unit
- 6. Electrical connection
Pressure Limiter
The mechanical pressure limiter is installed in the pressure accumulator. It limits the maximum pressure in the pressure accumulator.