DAF LF45, LF55 Series. Manual — part 283
©
200416
2-1
Fuel system
DIAGNOSTICS
ΛΦ45/55 series
4
1
2. FUEL SYSTEM
2.1 INTRODUCTION
If there is a fault in the system, it is usually
detected by the electronic unit in the form of a
fault code. This fault code can be read out using
DAVIE. The fault-finding table contains possible
causes of symptoms not detected by the
electronic unit.
DIAGNOSTICS
2-2
©
200416
Fuel system
1
ΛΦ45/55 series
4
2.2 FAULT-FINDING TABLE
SYMPTOM: ENGINE CAN BE STARTED, BUT DOES NOT RUN
Possible cause
Remedy
Poor fuel quality
Drain fuel, flush fuel system, replace the fuel filters
and fill fuel tank with fuel
Air in fuel system
Check for drawing in of air:
-
via the suction pipe
Fuel fine filter/coarse filter clogged
Replace fuel fine filter and clean the system
No fuel supply/high-pressure pump or fuel lift pump
defective; no delivery
Check:
-
the fuel level
-
the rail pressure
-
the pipes for blockage and leaks
-
the fuel lift pump
-
the high-pressure pump
SYMPTOM: ENGINE STALLS AND RUNS AGAIN AFTER RE-STARTING
Possible cause
Remedy
Air in fuel system
Check for drawing in of air:
-
via the suction pipe
SYMPTOM: ENGINE STARTS POORLY
Possible cause
Remedy
Poor fuel quality
Drain fuel, flush fuel system, replace the fuel filters
and fill fuel tank with fuel
Air in fuel system
Check for drawing in of air:
-
via the suction pipe
Fuel fine filter/coarse filter clogged
Replace fuel fine filter and clean the system
Injector(s) mechanically defective or clogged
Replace the injectors
High-pressure pump or fuel lift pump delivery too
low
Check:
-
the high-pressure pump
-
the fuel lift pump
Internal fuel leak between fuel supply pipe(s) and
injector(s)
Check the quantity of return fuel
SYMPTOM: ENGINE RUNS AT (INCREASED) IDLING SPEED AND DOES NOT RESPOND TO AC-
CELERATOR PEDAL
Possible cause
Remedy
Mechanical defect of accelerator pedal sensor
Check:
-
mechanical connection of sensor/accelerator
pedal
-
accelerator pedal sensor
©
200416
2-3
Fuel system
DIAGNOSTICS
ΛΦ45/55 series
4
1
SYMPTOM: DIESEL KNOCK DURING ACCELERATION
Possible cause
Remedy
Poor fuel quality
Drain fuel, flush fuel system, replace the fuel filters
and fill fuel tank with fuel
Air in fuel system
Check for drawing in of air:
-
via the suction pipe
Injector defective
Check the injectors
SYMPTOM: IRREGULAR RUNNING OF ENGINE
Possible cause
Remedy
Poor fuel quality
Drain fuel, flush fuel system, replace the fuel filters
and fill fuel tank with fuel
Air in fuel system
Check for drawing in of air:
-
via the suction pipe
Fuel fine filter/coarse filter clogged
Replace fuel fine filter and clean the system
Injector(s) mechanically defective or clogged
Replace the injectors
Injector defective
Check the injectors
High-pressure pump or fuel lift pump delivery too
low
Check:
-
the high-pressure pump
-
the fuel lift pump
SYMPTOM: REDUCED POWER AT ALL ENGINE SPEEDS
Possible cause
Remedy
Poor fuel quality
Drain fuel, flush fuel system, replace the fuel filters
and fill fuel tank with fuel
Fuel fine filter/coarse filter clogged
Replace fuel fine filter and clean the system
Injector(s) mechanically defective or clogged
Replace the injectors
Mechanical defect of accelerator pedal sensor
Check:
-
mechanical connection of sensor/accelerator
pedal
-
accelerator pedal sensor
High-pressure pump or fuel lift pump delivery too
low
Check:
-
the high-pressure pump
-
the fuel lift pump
SYMPTOM: REDUCED POWER ABOVE A CERTAIN ENGINE SPEED
Possible cause
Remedy
Fuel fine filter/coarse filter partially clogged
Replace fuel fine filter and clean the system
Injector(s) mechanically defective or clogged
Replace the injectors
Air leak in inlet system
Pressure-test the inlet system
DIAGNOSTICS
2-4
©
200416
Fuel system
1
ΛΦ45/55 series
4
High-pressure pump or fuel lift pump delivery too
low
Check:
-
the high-pressure pump
-
the fuel lift pump
Fault in electrical components/wiring of:
-
connectors
Check the electrical system
SYMPTOM: REDUCED POWER ABOVE A CERTAIN ENGINE SPEED
Possible cause
Remedy
SYMPTOM: ENGINE SLUGGISH WHEN ACCELERATING OR UNDER HIGH LOAD
Possible cause
Remedy
Internal fuel leak between fuel supply pipe(s) and
injector(s)
Check the quantity of return fuel
High-pressure pump or fuel lift pump delivery too
low
Check:
-
the high-pressure pump
-
the fuel lift pump
SYMPTOM: WHITE/BLUE SMOKE IS EMITTED
Possible cause
Remedy
Poor fuel quality
Drain fuel, flush fuel system, replace the fuel filters
and fill fuel tank with fuel
Air in fuel system
Check for drawing in of air:
-
via the suction pipe
Fuel fine filter/coarse filter clogged
Replace fuel fine filter and clean the system
Injector(s) mechanically defective or clogged
Replace the injectors
High-pressure pump or fuel lift pump delivery too
low
Check:
-
the high-pressure pump
-
the fuel lift pump
Fault in electrical components/wiring of:
-
connectors
Check the electrical system
SYMPTOM: BLACK SMOKE IS EMITTED
Possible cause
Remedy
Injector(s) mechanically defective or clogged
Replace the injectors
SYMPTOM: ENGINE OVERHEATED
Possible cause
Remedy
Poor fuel quality
Drain fuel, flush fuel system, replace the fuel filters
and fill fuel tank with fuel
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