Fuel supply

High-pressure direct injection, common rail fuel circuit mainly consisting of a fuel filter, a high-pressure pump, an in-tank low-pressure pump, a common rail and injectors electronically controlled by the engine management ECU.

FUEL FILTER

Fuel filter mounted in the engine compartment, to the left of the air filter.

LOW-PRESSURE FEED PUMP

Low-pressure fuel pump submerged in the tank, incorporating a fuel level gauge.

LOW-PRESSURE CIRCUIT PRESSURE

8.5 bar.

HIGH-PRESSURE PUMP

It consists of a shaft actuating 3 radial pistons (Fig.11). Its role is to supply high pressure and feed the injectors through the common rail. It does not require timing adjustment.

It is mounted on the left side of the engine and driven via the intake camshaft.

It is fitted with a fuel temperature sensor and a flow regulator.

INJECTION ORDER

1-3-4-2 (No. 1 on timing side).

HIGH-PRESSURE CIRCUIT PRESSURE

300 to 1,600 bar.

FUEL FLOW REGULATOR

Mounted on the flange of the injection pump, it regulates the fuel flow (Fig.11). The engine control unit controls the flow regulator using a pulse-width modulated signal. When the engine is switched off, the regulator cuts off the fuel supply to the high-pressure circuit components.

FUEL TEMPERATURE SENSOR

Mounted on the top of the high-pressure pump, it measures the fuel temperature (Fig.11). It is an NTC type sensor, so its electrical resistance decreases as the temperature rises. When the fuel temperature is too high, the injection rail pressure drops.

Fig. 11

High-pressure circuit

1. 1
   High-pressure pump
2. 2
   High-pressure pump drive (via intake camshaft)
3. 3
   Fuel supply
4. 4
   Fuel return
5. 5
   Fuel flow regulator
6. 6
   Fuel temperature sensor
7. 7
   High-pressure common rail
8. 8
   Rail pressure sensor
9. 9
   Pressure regulator
10. 10
    Injectors.

INJECTORS

The engine injectors have a 6-character IMA code (Fig.12) which contains the injector characteristics. This code is printed on each injector. If one of the injectors is replaced with a new one, the 'IMA' code must be programmed into the engine control unit using the diagnostic tester.

Fig. 12

HIGH-PRESSURE COMMON RAIL

The high-pressure common rail injection system regulates the high pressure, dampens the pressure pulses created by injection, and connects the high-pressure components together. It is made of mechanically welded steel and is fixed to the cylinder block. It carries a pressure and temperature sensor.

RAIL PRESSURE SENSOR

Mounted at the end of the rail (Fig.11), the sensor is a piezoelectric type that transmits a voltage signal representing the pressure in the rail. The engine control unit uses this signal to calculate injection times.

PRESSURE REGULATOR

Mounted at the end of the rail opposite the pressure sensor (Fig.11), it allows rapid pressure regulation. The rail pressure is regulated by the pressure regulator, which is controlled by the engine control unit.