Component description for high pressure pump - GF07.02-P-3010P

ENGINES 642.8 in MODEL 463.3 as of model year 2011

ENGINES 642.9 in MODEL 203.2, 164.8, 203.0, 164.1, 251.0, 221.0, 251.1, 221.1, 204.0/2 up to model year 2008/YoM 07

ENGINES 642.9 in MODEL 211.2/0, 219.3, 209.4/3, 211.6

ENGINES 642.9/8 in MODEL 461.3

ENGINES 642.9 in MODEL 463.3

Fig 1: Identifying High Pressure Pump & Quality Control Valve

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Location

The high pressure pump is mounted on the cylinder head at the left front.

Task

The high-pressure pump is a radial piston pump, with 3 pump elements set at 120°, which compresses the fuel supplied by the fuel pump (M3) and thus generates the rail pressure.

Fig 2: High Pressure Pump Function Diagram (Low Pressure Side)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Low-pressure side function

The fuel supplied by the fuel pump arrives at the high-pressure pump flange and from here is sent on to the quantity control valve and to the fuel pressure relief valve.

The quantity control valve controls the volume of fuel fed through the annular passage to the 3 pump elements of the high-pressure pump (fuel feed to high-pressure elements).

To lubricate the pump elements when the quantity control valve is closed (deceleration mode), fuel from the fuel feed is fed directly into the annular passage.

The fuel pressure relief valve limits the fuel pressure at the quantity control valve to about 5 bar. If this value is exceeded, the fuel pressure relief valve opens and passes the excess fuel back through the return line to the fuel tank.

The fuel pressure relief valve also sends some of the fuel to the eccentric shaft as lubricant.

Any air entrained by the fuel is passed through the fuel pressure relief valve into the high-pressure pump to the return line.

Fig 3: High-Pressure Pump Function Diagram (High Pressure Side)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

High pressure side

With its eccentric disk, the eccentric shaft moves the piston back and forth against the piston spring.

Filling the piston

The piston is moved down as a result of the piston spring. The fuel supplied by the fuel pump flows through the annular passage and fuel feed, and against the valve spring force through the valve into the cylinder. The ball valve prevents fuel from flowing back through the high pressure channel into the fuel tank.

High pressure production

The piston is moved upward by the upward movement of the eccentric shaft. This compresses the fuel. The valve closes the delivery volume against the fuel feed. Once the fuel pressure in the cylinder rises above the pressure in the high-pressure circuit, the ball valve opens and the fuel is delivered into the high-pressure circuit.