High pressure pump
The high-pressure fuel pump boosts the fuel pressure (range from 50 to 200 bar) and supplies fuel to the rail. The high-pressure pump is bolted onto the rear end of the vacuum pump. The drive shaft of the high-pressure pump is connected to the drive shaft of the vacuum pump.
| Index | Explanation |
|---|---|
| 1 | High pressure pump |
| 2 | Connection for the high pressure line to the rail |
| 3 | Volume control valve |
| 4 | Electrical connection |
| 5 | Low-pressure line connection fitting at electric fuel pump |
The volume control valve controls the fuel delivery pressure in the rail. The volume control valve is activated via a pulse-modulated signal (PWM signal) from the DME control unit. The PWM signal determines the throttle opening while also adjusting the fuel supply to provide the correct delivery rate for the engine's current load factor. In addition, there is the possibility to reduce the pressure in the rail. When a defect such as failure of a rail-pressure sensor is diagnosed in the system, electrical power to the flow-control valve is deactivated. The fuel then reaches the rail via a so-called bypass valve.
| Index | Explanation |
|---|---|
| 1 | High pressure pump |
| 2 | Connection for the high pressure line to the rail |
| 3 | Low-pressure line connection fitting at electric fuel pump |
| 4 | Volume control valve |
| 5 | 3 Pistons as well as intake and exhaust valves |
| 6 | Pressure relief valve |
| 7 | Bypass valve |
The volume control valve is a component of the high-pressure pump and can be removed during service.