Lull 944E-42 Service Manual - Manual (Page 229)

7.27 Model 644E-42/944E-42 Rev. 6/04
Engine: Cummins 4BT 3.9, B4.5T and QSB 4.5T
7.8.5 Fuel Filter Replacement
The fuel filter (4 or 9) must be changed at shorter
intervals with evidence of water or contaminated fuel.
1. Unlatch and open the engine cover.
2. Clean around the fuel filter head (4 or 9).
3. Unscrew the fuel filter and dispose of properly.
4. Clean the gasket surface of the filter head and
replace the o-ring.
5. Fill the new fuel filter with clean No. 2 diesel fuel.
6. Lubricate the o-ring seal with clean No. 2 diesel fuel.
7. Install the fuel-filled filter and hand tighten. DO NOT
overtighten.
NOTE: Mechanical over-tightening may distort the
threads or damage the sealing ring.
8. Close and latch the engine cover.
Controlled venting is provided at the injection pump
through the fuel drain manifold. Small amounts of air
introduced by changing the fuel filter element will be
vented automatically as long as the element was filled
with fuel prior to installation.
7.8.6 Bleeding Air From The Fuel System
Air must be vented from the fuel system whenever any
component between the fuel tank and the injection pump
has been disconnected, or when the system has been
emptied or run out of fuel.
IMPORTANT! DO NOT attempt to start the engine until
the injection pump has been filled and primed with fuel.
Serious damage to the lift pump will result due to lack of
proper lubrication.
1. To vent the low pressure lines and fuel filter, open
the vent screw (17) located on the filter head.
2. Operate the hand plunger (3 or 8) on the lift pump (2
or 7) until fuel flowing from the fitting is free of air.
3. Tighten the vent screw (17) and torque to 7 lb-ft
(9 Nm).
The process of venting high pressure fuel lines involves
energizing the starter motor to rotate the crankshaft
which will, in turn, pump any unwanted air from the fuel
lines.
4. To vent the high pressure fuel lines (18), loosen one
fitting (19) at the injector (20).
5. Turn the ignition switch to the START position and
crank the engine for a maximum of 15 seconds or
until fuel, free of air, comes out of the injector fitting.
6. Tighten the fitting. Torque to 22 lb-ft (30 Nm).
7. Repeat Steps 4 thru 6 for each fitting until the engine
runs smoothly.
With the engine running, visually check for leaks. Turn
ignition switch OFF.
WARNING:
DO NOT bleed the fuel sys-
tem of a hot engine. Doing so could create a
fire hazard. Allow the engine to cool before
bleeding the fuel system.
CAUTION:
When using the starting
motor to vent the fuel system, DO NOT
energize the starter solenoid or crank the
engine for more than 15 seconds at a time;
wait two minutes between engagements.
WARNING:
KEEP CLEAR of spraying
fuel. Fuel can spray when venting high
pressure lines. The fuel pressure is sufficient
to penetrate the skin and cause serious bodily
injury. Wear protective clothing and safety
glasses.
OU0940
17
OU0250
18
19
20