5.5.6 Pressure control valve
The pressure control valve (PCV) (002, Figure 5-38) is attached to the fuel rail (007) and has
the functions that follow:
•
Usual operation
During usual operation the engine software controls the fuel flow and thus the fuel
pressure. The PCV is closed because the pressure in the fuel rail is lower than necessary
to open the PCV.
•
Operation with a defective item
If an item becomes defective or unserviceable (for example missing or incorrect control
signals, a flow control valve of a fuel pump is unserviceable), the operator must do the
related procedures. Then the engine control sets the fuel pumps to the maximum flow
and the PCV controls the pressure in the fuel rail. The PCV opens to gradually drain
sufficient fuel to keep the adjusted pressure. Prevent a longer engine operation time in
this operation mode to prevent a possible damage to the PCV.
After this operation mode, do a check of the PCV for a tight seal. The seal can be
damaged. You can hear a loud sound like a whistle. Replace the PCV seal if necessary.
•
Engine stand-by
During engine stand-by, the engine software opens the PCV. This gives a constant flow of
fuel through the fuel system.
•
Emergency stop
If an emergency stop is activated, the safety system operates the solenoid valve (001)
and the fuel pressure in the fuel rail decreases immediately to less than 200 bar (usually
to 0 bar). Thus, fuel injection is not possible.
Attached to the PCV are the solenoid valve (001), the relief valve (003) and the fuel return
pipes (004, 005). As a safety device the relief valve opens, if the fuel pressure is more than the
specified pressure.
X92DF
AA00-5562-00AAA-043A-A
Operation Manual Pressure control valve
Winterthur Gas & Diesel Ltd.
- 216 - Issue 002 2020-08
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