Bosch 0 986 613 200 Handbuch Seite 22

1.3 Use of Diesel Set 3
1.3.1 Pressure build-up testing of diesel high pressure pumps under engine
start conditions
Use in event of complaints such as:
- engine does not start, starter turns over
- engine cuts out, does not restart, starter turns over (breakdown)
Description of principle involved:
The pressure pickup module is connected by the black 60 MPa (600 bar) hose directly to the
high pressure port on the high pressure pump.
The high pressure line is detached from the pump for the purpose. The engine cannot be
started in this condition!
While the starter is being operated the fuel flow is collected in the module's reservoir and the
pressure is indicated by the digital pressure gage.
The pressure attained is a measure of the capacity of the high pressure pump to build up
pressure under engine start conditions.
When a pressure of around 50 MPa (500 bar) is reached a relief valve in the module opens to
protect the high pressure pump. The overflow flows into the module's reservoir.
1.3.2 Rail pressure sensor comparative test in Common Rail system
Use in event of complaints such as:
- lack of power (no fault memory entry)
Description of principle involved:
The pressure pickup is connected directly to a high pressure port on the rail by the
blue 200 MPa (2000 bar) hose.
For the purpose the high pressure line is detached between the rail and an easily accessible
injector.
The digital pressure gage connected to the pressure pickup indicates the actual pressure in the
rail.
A diagnostic tester connected to the vehicle indicates the pressure by way of the rail pressure
sensor fitted in the rail, and so the possibly incorrect value.
Notes:
- During the test the engine runs on n–1 cylinders.
It is possible to run the engine on all cylinders by connecting up a second 200 MPa (2000 bar)
hose (special accessory item, not supplied).
- Variations in engine speed and/or rail pressure across engine test functions are in principle
possible.
Always observe the vehicle and system-specific information.
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