Fuel Supply, Function - GF07.10-D-1003HD
ENGINES 651.955/956/957 in MODEL 906
with CODE (XZ1)
with CODE (MZ0) Blue EFFICIENCY
Function requirement
- "Tml. 15 ON"
- "Tml. 87 ON"
General
The fuel supply supplies filtered fuel out of the fuel tank in adequate amounts under all operating conditions at an adequate pressure to the following injectors.
- Cylinder 1 injector (Y76/14)
- Cylinder 2 injector (Y76/15)
- Cylinder 3 injector (Y76/16)
- Cylinder 4 injector (Y76/17)
Function sequence
The function sequence for fuel supply is described in the following steps:
- Function sequence for fuel pump actuation
- Function sequence for low-pressure fuel circuit
- Function sequence for high-pressure fuel circuit
- Function sequence for safety fuel shutoff
Function sequence for fuel pump actuation
Switching on of the fuel pump with fuel level sensor (M3/5) (for model 906) takes place over the fuel pump relay (K40/9k3) (for model 906) by the CDI control unit (N3/28).
The fuel pump pressure generated is monitored over the fuel pressure sensor (B4/7) by the electronically regulated fuel pump (N118) (model 639) or the FSCU (N118/5) (model 906).
Function sequence for low-pressure fuel circuit
The fuel low-pressure circuit consists of the following components:
- Fuel tank
- Fuel pump with fuel tank sensor
- Fuel lines
- Fuel filter
- Quantity control valve (Y94/3)
- High-pressure pump (M41/3), low-pressure side
- Fuel temperature sensor (B50/5)
- Pressure regulating valve (Y74/5), low-pressure side
- Cylinder 1 injector, low-pressure side
- Cylinder 2 injector, low-pressure side
- Cylinder 3 injector, low-pressure side
- Cylinder 4 injector, low-pressure side
During actuation the fuel pump with fuel level sensor suctions the fuel out of the fuel feed module and pumps it through the fuel filter to the high-pressure pump.
The fuel pressure is regulated variably to about 4.0 bar according to the fuel requirements via the feed pressure regulating valve integrated in the high-pressure pump.
The quantity control valve also regulates the supply of fuel depending on the engine operating point to the high-pressure pump, in order to increase engine efficiency and to keep the fuel temperature low.
The leak fuel from the following injector is suctioned over a venturi into the high-pressure pump:
- Cylinder 1 injector
- Cylinder 2 injector
- Cylinder 3 injector
- Cylinder 4 injector
The leak fuel and fuel that is not required are fed back to the fuel tank via the return line.
The fuel filter heater with water level sensor (R53) is integrated into the fuel filter in order to ensure the flowability of the fuel at low outside temperatures and to monitor the water level in the fuel filter. The signal for the fuel filter heater with water level sensor is read in by the CDI control unit. Actuation of the heating element for the fuel filter heater with water level sensor takes place by the SAM control unit (N10).
Function sequence for high-pressure fuel circuit
The high-pressure circuit consists of the following components:
- High-pressure pump
- Rail
- High-pressure line
- Rail pressure sensor (B4/16)
- Pressure regulator valve
- Cylinder 1 injector
- Cylinder 2 injector
- Cylinder 3 injector
- Cylinder 4 injector
The high-pressure pump delivers the fuel into the rail dependent on the signal from the accelerator pedal module (B37/3) (for model 906) and the motor RPM. From the rail, the fuel flows through the high-pressure lines to the injectors. The injectors inject finely atomized fuel selectively into each cylinder.
The CDI control unit calculates the injection quantity selectively for each cylinder based on a characteristics map for the respective operating condition. The injection quantity depends on the fuel pressure in the rail and the actuation time of the injectors. The fuel pressure in the rail is controlled by the pressure regulating valve and quantity control valve.
The fuel pressure actually present in the rail is measured by the rail pressure sensor and transmitted continuously to the CDI control unit. The fuel temperature is measured by the fuel temperature sensor and transmitted continuously to the CDI control unit.
Function sequence for safety fuel shutoff
In order to achieve traffic and passenger safety, a safety fuel shutoff may occur.
The CDI control unit controls the safety fuel shutoff on the basis of the following sensors and signals:
- Crankshaft sensor (L5/10), engine speed
- For Lowline airbag control unit (N2/14) (except code (SH6) Driver thoraxbag (in backrest) (for model 906), except code (SH7) Thoraxbag for driver and front passenger (in backrest) or code (SH9) Windowbag for driver and front passenger, or with Highline airbag control unit (N2/15) (for model 906) (with code (SH6) Thoraxbag for driver (in backrest) (for model 906), with code (SH7) Thoraxbag for driver and front passenger (in backrest) or with code (SH9) Windowbag for driver and front passenger), a direct crash signal and via interior CAN (CAN B)
The safety fuel shutoff is activated by the CDI control unit in the following conditions:
D Absence of the engine speed signal
D Crash signal
Absence of the engine speed signal
If the engine speed signal generated by the CDI control unit is missing the fuel pump with fuel level sensor will be switched off.
Crash signal
If the CDI control unit receives a crash signal indirectly via CAN B or directly from the lowline airbag control unit (except code (SH6) Thoraxbag for driver (in backrest) (for model 906), except code (SH7) Thoraxbag for driver and front passenger (in backrest) or code (SH9) Windowbag for driver and front passenger, or from Highline airbag control unit (with code (SH6) Thoraxbag for driver (in backrest) (for model 906), with code (SH7) Thoraxbag for driver and front passenger (in backrest) or with code (SH9) Windowbag for driver and front passenger), the fuel pump with fuel level sensor switches off.
| CDI control unit, component description | N3/28 | GF07.16-D-6000HD |
|---|---|---|
| Component description for fuel pressure sensor | B4/7 | GF47.20-S-2030S |
| Component description for rail pressure sensor | B4/16 | GF07.04-D-6210HD |
| Component description for the crankshaft position sensor | L5/10 | GF07.04-D-6011HD |
| Component description for fuel pump | M3/3 M3/5 Model 906 |
GF47.20-S-2000S |
| Component description for high-pressure pump | M41/3 | GF07.02-D-3010HD |
| Component description for fuel system control unit | N118 With engine 651.940 N118/5 With engine 651.955/956/957 |
GF47.40-S-2001S |
| Component description for pressure regulating valve | Y74/5 | GF07.05-D-6020HD |
| Component description for fuel injectors | Y76/14, Y76/15, Y76/16, Y76/17 | GF07.03-D-6120HD |
| Component description for quantity control valve | Y94/3 | GF07.05-D-6010HD |