Attention. When carrying out any work on the fuel system, familiarize yourself with the rules for maintaining cleanliness and instructions. Strictly observe these rules and instructions before starting work and during their implementation. In order to avoid running an unfilled high-pressure fuel pump and to achieve a quick start of the engine after replacing parts, it is imperative to take into account the following points. After removing or replacing parts/components between the tank and the high-pressure fuel pump, it is necessary to perform the basic setting "Checking the fuel booster pump" to purge the fuel system. After removing or replacing the auxiliary fuel pump, fuel line (between tank and high pressure fuel pump) or fuel filter, before the first engine start, it is necessary to perform the basic setting "Checking the fuel booster pump" 1 time. After removing or replacing the high-pressure fuel pump, it is necessary to perform the basic setting "Checking the fuel booster pump" 3 times before the first engine start. Perform the first refueling after installing the high-pressure pump.
System overview 1. Fuel metering valve "N₂90": do not open; 2. High pressure fuel pump: with fuel metering valve "N₂90"; after replacing the fuel injection pump, it is "necessary" to carry out the first refueling (to prevent dry running); 3. Fuel rail (high pressure energy accumulator): cylinder bank 1; 4. Fuel pressure regulating valve "N₂76": on cylinder bank 1; disposable; 5. Fuel pressure sensor "G247": 30 Nm; on cylinder bank 2; 6. Fuel rail (High pressure energy accumulator): for cylinder bank 2; 7. Nozzles (piezo injectors): injectors 1...6; 8. Drainage pipelines (return fuel line): Do not disassemble the return fuel lines - they can only be replaced together with the pressure reducing valve; after replacement, let the engine run for about 2 minutes at idle speed to remove air from the fuel system and then check the fuel return lines for leaks; 9. Pressure reducing valve: the function of the pressure reducing valve is to ensure residual pressure in the return fuel lines (scope of control) approx. 10 bar; this amount is necessary for the operation of piezo injectors; the pressure reducing valve should only be replaced together with the return fuel lines; after replacement, let the engine run for about 2 minutes at idle speed to remove air from the fuel system; check the pressure reducing valve; 10. Fuel cooler: installed on the bottom of the car; 11. Fuel tank: with fuel booster pump "G6"; 12. Heating valve; 13. Additional fuel pump "V393"; 14. Fuel filter
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