Contents: Examination ↡ Adjustment ↡
In order for the fuel pump to deliver fuel to each cylinder at the required time, it is necessary to check and, if necessary, adjust the fuel injection timing if the high-pressure fuel pump or other related components have been removed.
To adjust the fuel injection timing, the high-pressure fuel pump has a setting hole closed with a threaded plug. Fuel injection into the first cylinder occurs when the protrusion on the regulator body inside the fuel pump passes near the setting hole.
When the positioning lug on the governor body is precisely aligned with the center of the positioning hole, it is necessary to check the position of the crankshaft using the pointer on the timing chain cover and the marks on the crankshaft vibration damper. In this position of the crankshaft and the high-pressure fuel pump, indirect fuel injection is ensured.
A more precise measurement of the start of fuel injection is made using special equipment and a sensor that is screwed into the installation hole of the fuel pump. Since this equipment is only available at Mercedes-Benz and Bosch dealers, an alternative method is described below. It should be noted that the alternative method only provides an approximate setting that allows the engine to start and, at the first opportunity, the adjustment should be made at a service station.
Examination
1. Remove the ground cable from the battery.
2. Remove the radiator fan and shroud.
3. Unscrew the installation hole plug on the side of the high pressure fuel pump.
4. Using a small mirror, observe the position of the regulator body through the mounting hole.
5. Turn the engine crankshaft in the operating direction until the mounting lug on the governor housing aligns with the center of the mounting hole (see fig. Using a special tool to prevent the regulator body from turning).
6. Using the mark on the torsional vibration damper, combined with the pointer, determine the crankshaft installation angle (see Fig. Installing the piston of the first cylinder in the 15° position).
7. Check the obtained value against the technical specifications and, if necessary, make adjustments.
Adjustment
Location of fuel injection timing adjusting screw
1. By turning the engine crankshaft, set the engine to the fuel injection timing position.
2. Loosen the three bolts securing the front of the fuel pump to the mounting flange. Also loosen the bolt securing the rear of the fuel pump to the bracket.
3. Unscrew the plug from the installation hole located on the side of the fuel pump.
4. Using a small mirror, look at the regulator body through the mounting hole. Turn the adjusting screw located on the side of the high-pressure fuel pump until the protrusion on the regulator body aligns with the center of the mounting hole (see Fig. Location of fuel injection timing adjusting screw).
Attention! When turning the adjusting screw to the right, the injection advance moment decreases, and when turning to the left, it increases.
5. After completing the adjustment, tighten all high pressure fuel pump mounting bolts to the specified torque.
6. Screw the plug into the mounting hole and tighten it to the required torque.
7. This method only provides an approximate setting of the fuel injection timing and should be adjusted at a service station at the first opportunity.