Perkins NJ Series Troubleshooting Manual page 67

SENR9982-01
4. If the oil is of an acceptable quality, refer to
"Operation in Cold Conditions".
Low Engine Temperature
1. The operating temperature of the engine will affect
the rate of fuel consumption. Operation of the
engine below the correct temperature will increase
fuel consumption. Failure of the water temperature
regulator can prevent the engine from operating at
the correct temperature.
2. If the engine operating temperature is low, check
the operation of the water temperature regulator. If
the water temperature regulator does not operate
correctly, a new water temperature regulator must
be installed. Refer to Disassembly and Assembly,
"Water Temperature Regulator - Remove and
Install".
Prolonged Operation at Idle Speed
Prolonged operation of the engine at idle speed
increases fuel consumption.
When the engine is operated at idle speed, the fuel
that is consumed provides no useful work. Prolonged
operation at idle speed will cause a measurable
deterioration in the overall fuel consumption of the
engine.
Operation of the engine for long periods at idle
speed will cause a deterioration of the internal
components of the engine. A deterioration of the
internal components of the engine will increase fuel
consumption.
Engine Operating Speed
The operating speed of the engine will affect the rate
of fuel consumption.
High engine speed will increase fuel consumption.
At high engine speeds, internal power losses in
the engine increase and more power is required to
drive the alternator and the fan. These power losses
increase fuel consumption.
Lugging down the engine to a low engine speed will
increase fuel consumption. At low engine speeds, the
combustion efficiency of the engine is reduced. This
will require more fuel to be used.
Air Inlet and Exhaust System
Leakage of gas or an increased restriction in either
the air intake or the exhaust system can reduce
the flow of combustion gas through the engine. A
change in the flow of combustion air into the engine
adversely affects combustion efficiency and the rate
of fuel consumption.
1. Check the air intake system for leakage or
restrictions. Refer to Testing and Adjusting, "Air
Inlet and Exhaust System".
2. Check the exhaust system for leakage or
restrictions. Refer to Testing and Adjusting, "Air
Inlet and Exhaust System".
3. Repair all defects. Verify that the repair has
eliminated the fault.
Reduced Pressure of Intake Air
1. If the pressure of the intake air at the intake
manifold is lower than normal, either the speed
of the engine will need to be higher or more fuel
must be injected in order to produce the same
power. Either of these conditions will increase the
fuel consumption.
Note: If the engine is equipped with a wastegate
regulator, low pressure in the air intake will create a
526-07 diagnostic code.
2. Check the pipe from the outlet of the turbocharger
compressor to the intake manifold for leaks. If
necessary, repair any leaks.
3. Check for the correct operation of the wastegate in
the turbocharger. Refer to Testing and Adjusting,
"Turbocharger Wastegate - Test".
4. If the turbocharger is suspected as being faulty,
replace the turbocharger. Refer to Disassembly
and Assembly, "Turbocharger - Remove" and
Disassembly and Assembly, "Turbocharger -
Install".
Excessive Valve Lash
Excessive valve lash will cause a change in the
timing of the opening and closing of the inlet and
exhaust valves. Excessive valve lash can cause
a reduction of the flow of combustion air into the
engine. Reduced flow of combustion air will increase
the fuel consumption rate.
Refer to the Troubleshooting Guide, "Excessive Valve
Lash".
Failure of the Primary Speed/Timing
Sensor
If the primary speed/timing sensor fails, the engine
will continue to operate using the signal from the
secondary speed/timing sensor on the fuel rail
pump. The secondary speed/timing sensor is less
precise than the primary speed/timing sensor. Timing
differences between the secondary speed/timing
sensor and the primary speed/timing sensor may
cause an increase in fuel consumption.
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Troubleshooting Section