Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
148
10.
DTC P0251 The control line of fuel level control unit is open.
P0252 The ECU internal driver module of fuel level control unit is overheating.
P0253 The control line of fuel level control unit is short to ground.
P0254 The control line of fuel level control unit is short to high level.
Fault Description: The fuel metering unit is for adjusting the fuel supply and the fuel pressure. When the control coil
of metering unit is off, the inlet fuel metering proportional valve of the unit shall be closed, cutting off the fuel
supplied to the high pressure fuel pump plunger component. When the control coil of metering unit is electrified, the
ECU shall change the fuel inlet sectional area of metering component via pulse signal according to the actual demand,
through which, the fuel supplied to the high pressure fuel pump plunger component shall be changed. If the fuel
metering control signal voltage detected by ECU is abnormal, the DTC shall be generated.
Diagnosis Hint: The metering component is mounted at the fuel inlet of high pressure pump. The engine’s fuel
supply shall be affected directly by the opening sectional area of the fuel metering unit control valve. Provided that the
fuel metering unit control line is normally connected, monitor the engine fuel supply amount and pressure while
moving relevant connector and wire to check if any fault is triggered. If any, the indication of fault diagnostic unit
shall change. This is help for locating the intermittent failure.
The intermittent failure may be caused by poor contact of control part. As for poor contact between ECU and fuel
metering unit, please check the ECU harness connector for the following conditions:
− Loose terminal
− Poor matching and connection
− Breakage of keeper
− Distortion or damage of terminal
− Poor contact between terminal and wire
Check the harness for any damage. If the harness appears normal, observe the fuel pressure indicated on the diagnostic
tool while moving relevant connector and harness of fuel metering unit. If the pressure indication changes, there must
be failure in that part.
Terminal ECU
A19 Power supply terminal of fuel metering unit
A49 Signal terminal of fuel metering unit
Control of fuel metering unit
Fuel metering unit
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