Checking regulation of the fuel pressure
The pressure in the fuel injection system can reach approximately 650 kPa when this diagnostic trouble code (DTC) is stored. Use an adapted manometer.
HINT: The method below is intended to check the pressure in the fuel system by reading out the fuel pressure and the fuel pump (FP) work load. If the manometer for pressures up to 650 kPa is connected, the fuel pressure sensor can also be checked during this test.
- Disconnect the manometer unless it is adapted for pressures higher than 650 kPa
- Run the engine to operating temperature. Allow the engine to idle
- air conditioning (A/C) off
- Read off the fuel pressure and the fuel pump (FP) work load.
- The upper digital display and the graphic display (red font color) indicate the absolute fuel pressure, calculated from the fuel pressure sensor
- The center digital display (blue font color) indicates the current work load required for the fuel pump (FP) to maintain the present fuel pressure (normal value 50 % 10 %)
- The lower digital display indicates the relative fuel pressure (white font color), calculated from the fuel pressure sensor and the atmospheric pressure sensor (= absolute pressure minus atmospheric pressure). If a manometer is connected during the test, it should indicate this pressure.
Check the fuel pressure value together with the value for the fuel pump (FP) work load. The requested pressure is 380 kPa at idling speed. A (relative) fuel pressure lower than 380 kPa together with a high fuel pump (FP) work load indicates a fault in pressure regulation.
Is the function OK?
- YES
Refer to Checking components
- NO
Refer to Checking components