(Table 38, contd)
Troubleshooting Test Steps Values Results
7. Coolant Temperature
Note: 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.
A. Check that the water temperature regulator is operating cor-
rectly. Refer to Systems Operation, Testing, and Adjusting,
“Water Temperature Regulator - Test”.
Coolant
temperature
Result: The water temperature regulator is not operating
correctly.
Replace the water temperature regulator. Verify that the re-
pair corrected the fault.
Result: The water temperature regulator is operating
correctly.
Proceed to Test Step 8.
8. Prolonged Operation at Idle Speed
Note: Prolonged operation of the engine at idle speed increases
fuel consumption.
A. Check for extended periods of engine operation at idle speed.
Extended idle
operation
Result: The engine is operating at idle speed for extended
periods.
When possible, stop the engine to conserve fuel.
Result: The engine is not operating at idle speed for ex-
tended periods.
Proceed to Test Step 9.
9. 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 en-
gine speeds, internal power losses in the engine increase and
more power is required to drive the alternator and the fan. These
losses of power increase fuel consumption.
Lugging down the engine to a low engine speed will increase
fuel consumption. At low engine speeds, the combustion effi-
ciency of the engine is reduced and more fuel is required.
A. Check that the engine has been operated at a suitable engine
speed.
Engine speed Result: The engine has been operated at an unsuitable
speed.
Operate the engine at a suitable speed.
Result: The engine has been operated at a suitable speed.
Proceed to Test Step 10.
10. Air Intake and Exhaust System
A. Check the air filter restriction indicator, if equipped.
B. Check the air intake and exhaust systems for the following
defects:
· Blockages
· Restrictions
· Damage to lines or hoses
Refer to Systems Operation, Testing and Adjusting, “Air Inlet and
Exhaust System - Inspect”.
Air and Exhaust
System
restrictions
Result: The air filter is restricted.
Replace the air filter.
Result: There are system restrictions.
Repair any defects in the air inlet and exhaust systems.
Result: The air intake and exhaust system is OK.
Proceed to Test Step 11.
(continued)
90 UENR0612
Symptom Troubleshooting
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