
RENR9968-02 31
Testing and Adjusting Section
1. Determine if wat er a n d/ or c on taminants are
present in the fuel. Check the water separator (if
equipped). If a water separator is not present,
proceed to Step 2. Drain the water separator, if
necessary. A full fuel tank minimizes the potential
for overnight condensation.
Note: A water separator can appear to be full of fuel
when t he wate r separator is a ct ua lly full of water.
2. Determine if contaminants are present in the
fuel. Remove a sample of fuel from the bottom
of the fuel tank. Visually inspect the fuel sample
for contaminants. The color of the fuel is not
necessarily an indication of fuel quality. However,
fuel that is black, brown, and/or similar to sludge
can be an indication of the growth of bacteria or
oil contamination. In cold tempe r atures, cloudy
fuel indicates that the fuel may not be suitable
for operating conditions. The following methods
canbeusedtopreventwaxfromcloggingthefuel
filter:
•
Fuel heaters
•
Blending fuel with additives
•
Utilizing fuel w ith a low cloud point such as
kerosene
Refer to Operation and Maintenance Manual,
SEBU6251, “Caterpillar Com mercial Die se l
Engine Fluids Recommendations”, “Fuel
Recom mendations” for mo re information.
3. Check fuel API with a 9U-7840 Fluid and Fuel
Calibration Gp for low power complaints. The
acceptable range of the fuel API is 30 to 45 when
the API is measured at 15 °C (60 °F ), but there is
asignificant difference in energy within this range.
Refer to Tool Operating Manual, NEHS0607 for
API correction factors when a low power problem
is present and API is high.
Note: A correction factor that is greater than 1 may be
the cause of low power and/or poor fuel consumption.
4. If fuel qua lity is still suspected as a possible
cause to problems regarding engine performance,
disconnect the fuel inlet line, and temporarily
operate the engine from a separate source of
fuel that is known to be good. This will determine
if the problem is caused by fuel quality. If fuel
quality is determined to be the problem, drain the
fuel system and replace the fuel filters. Engine
performance can b e affected by the following
characteristics:
•
Cetane number of the fuel
•
Air in the fuel
•
Other fuel characteristics
i02285479
Fuel System - Prime
SMCS Code: 1258-548
The Secondary Fuel Filter Has
Been Replaced
Fuel leaked or spilled onto hot surfaces or elec-
trical components can cause a fire. To help pre-
vent possible injury, turn the start switch off w hen
changing fu el filters or w ater separator elements.
Clean up fuel spills immediately.
NOTICE
Use a suitable container to catch any fuel that might
spill. Clean up any spilled f uel immediately.
NOTICE
Do not allow dirt to enter the fuel system. Thoroughly
clean the area around a fuel system component that
will be disconnected. Fit a suitable cover over discon-
nected fuel system component.
Note: Refer to Operation and Maintenance M anual,
“Fuel System Secondary Filter - Replace” for
information on replacing th e filter.
1. Turn the keyswitch to the “OFF” position.
2. Open the air purge screw for the fuel filter by three
full turns. Do not remove the a ir purge screw.
NOTICE
Do not crank the engine continuously for more than
30 seconds. Allow the starting motor to cool for two
minutes before cranking the engine again.
3. Start the engine. The engine should start and the
engine s hould run smoothly. If the engine does
not start after 30 seconds, allow the starter m otor
to cool for two minutes before attempting to start
the engine again.
Note: You may use the hand priming pump (if
equipped) for the fuel filter instead of starting the
engine and running the engine .
4. While the engine is running, observe the air purge
screw. When a small drop of fuel appears at the
threads of the air purge screw, close and tighten
the air purge screw.