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4. Open the drain
valve by turning
two to three turns.
When fuel empties
from the valve,
all the water
has been drained.
Close the valve
hand-tight.
5. Remove the fuel-resistant container and
properly dispose of the contaminated fuel.
To find out how to properly dispose of
contaminated diesel fuel, seeEngine Oil
(Caterpillar
®Diesel Engine) on page 268or
Engine Oil (Gasoline Engine) on page 268or
Engine Oil (DURAMAX
®/Isuzu Diesel
Engine) on page 272.6. Install the fuel cap.
7. Start the engine and let it run for a few
minutes. If the engine stalls, the fuel system
may need to be primed. While draining
the water from the fuel filter, air may enter the
fuel system. If air has entered the fuel
system the fuel system will need to be primed.
If the water-in-fuel light comes on again after
driving a short distance or the engine runs rough
or stalls, a large amount of water has probably
been pumped into the fuel tank. The fuel
tank should be purged.
Fuel Priming
If your vehicle has a Caterpillar®diesel engine,
see the Caterpillar®Diesel Engine Operation and
Maintenance Manual provided with your vehicle.
If your vehicle has a DURAMAX
®/Isuzu diesel
engine, in order for the fuel system to work
properly, the fuel lines must be full of fuel and
contain no air. If air gets into the fuel lines, it will
be necessary to prime the fuel lines to eliminate air
before operating the vehicle.
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Air can get into the fuel lines if any of the following
happen:
•The vehicle runs out of fuel.
•The fuel filter is removed for servicing or
replacement.
•The fuel lines are removed or disconnected
for servicing.
•The fuel filter water drain valve is opened
while the engine is running.
If one or more of the above occurred, it is very
likely that air has entered your fuel system and that
you will need to prime the fuel system before
operating the vehicle.
Air in the fuel lines will not harm the engine or the
vehicle. However, the engine may not be able
to start until the fuel system is primed and the air
is removed.
Priming the 6.6L DURAMAX®Diesel
Engine
If your vehicle is equipped with the 6.6L
DURAMAX®diesel engine, it has a priming pump
which is part of the engine mounted fuel filter.
The vent valve and the fuel filter primer pump are
located on top of the fuel filter housing. The
priming pump is hand operated and is designed to
bring fuel to the engine to eliminate any air that
may be in the fuel lines.
To prime the 6.6L DURAMAX
®diesel engine, do
the following:
1. Make sure there is fuel in the tank.
2. Make sure the fuel filter had been installed
and properly tightened.
3. Make sure the fuel lines are properly
connected and the fuel filter is cool enough
to touch.
4. Remove any dirt from the fuel filter head and
vent valve by wiping with a cloth.
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5. Open the fuel filter
vent valve by turning
the screw
counterclockwise
several full turns.
6. Repeatedly push
down on the fuel
filter primer
pump with the palm
of your hand. Let
the pump return
upward between
pushes.7. Operate the priming pump until a small
amount of fuel seeps from the vent valve.
When you see the fuel, the filter is now full of
fuel and the system should be primed.
8. Close the vent valve.
9. Clean any fuel which accumulated on the fuel
filter.
10. Start the engine and let it idle for a few
minutes.
11. Check the filter for leaks.
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Priming the 7.8L Isuzu 6H Diesel Engine
If your vehicle is equipped with the 7.8L Isuzu 6H
diesel engine, use the following procedure to
prime the engine:
1. Make sure there is fuel in the fuel tank.
2. Make sure the specified fuel filter is properly
installed.
3. Make sure the fuel lines are securely
connected.
4. Make sure the fuel filter is cool to the touch.
5. Use a clean cloth to remove dirt and oil
from the fuel filter head and breather valve.6. Use the palm of your hand to repeatedly
press and release the plunger (1) at the
top of the fuel filter priming pump. Continue
until the plunger resistance becomes firm. This
may take from 20 to 100 times, depending
upon fuel tank location.
7. Turn the fuel filter breather valve screw (2)
counterclockwise several turns to open the
breather valve.
8. Use the palm of your hand to repeatedly
press and release the plunger (1) at the
top of the fuel filter priming pump until fuel
begins to seep from the breather valve.
9. Tighten the fuel filter breather screw (2) to the
specified torque, 4.9
Y(43 in. lbs).
10. Use the palm of your hand to press and
release the plunger (1) at the top of the
fuel filter priming pump about 20 more times.
This sends fuel to the engine.
11. Use a clean cloth to remove any fuel from the
fuel filter and surrounding area.
12. Start the engine and allow it to idle for a
few minutes.
13. Check the fuel filter for leakage.
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