56 KENR9126
Troubleshooting Section
•
Reduced pressure of intake air
•
Excessive valve lash
•
Failure of the
primary speed/timing sensor
Recommended A
ctions
Diagnostic Codes
1. Use the electronic service tool to check for any
diagnostic codes that may be related to high fuel
consumptio
n.
Misreading of Fuel Level
1. Monitor the fuel consumption over a period of 50
engine hours. If the fuel consumption is excessive,
perform th
e following procedure.
Fuel Quality
1. The quality of the fuel that is used in the engine
will affect the rate of fuel consumption.
2. If the fuel is not of an acceptable quality, drain the
fuel system and replace the fuel filters. Refill the
fuel sys
tem with fuel of an acceptable quality.
3. If the fuel is of an acceptable quality, refer to
“Quali
ty of Oil”.
Quality of Oil
1. The nominal viscosity of the lubricatin g oil that
is used in the engine will affect the rate of fuel
consu
mption. The viscosity of lubricating oil is
defined by the SAE grade of the lubricating oil.
The grade of the lubricating oil must be correct
for th
e ambient conditions. Lubricating oil that is
intended for use in high ambient temperatures
will have a negative effect upon the rate of fuel
cons
umption in cold ambient temperatures.
2. The actual viscosity of the lubricating oil that is
used
in the engine will change throughout the
service life of the oil. Lubricating oil that is heavily
contaminated will have a negative effect upon the
rat
e of fuel consumption.
3. If the oil is not of an acceptable quality or if the oil
has
exceeded the service life, drain the oil system
and replace the oil filters. Refill the oil system with
oil of an acceptable quality.
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 t
he correct temperature will increase
fuel consumption. Failure of the water temperature
regulator can prevent the engine from operating at
the correct t
emperature.
2. If the engine operating temperature is low, check
the operati
on of the water temperature regulator. If
the water temperature regulator does not operate
correctly, a new water temperature regulator must
be installe
d.
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
operatio
n 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
compone
nts of the engine. A deterioration of the
internal components of the engine will increase fuel
consumption.
Engine Operating Speed
The ope
rating speed of the engine will affect the rate
of fuel consumption.
High e
ngine 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.
Lugg
ing 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 Inle t 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
re
strictions.
2. Check the exhaust system for leakage or
r
estrictions.
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