Switching Off Main Injection
Main injection is switched off when:
²Engine speed is too high >4700 - 4800 rpm
²Main injection quantity too low
²Low fuel pressure in fuel rail
²Engine off
²External quantity control
²Deceleration mode
Calculating Main Injection
The quantity of main injection is calculated by:
²Engine speed
²Atmospheric pressure
²Coolant temperature
²Boost air temperature
²Fuel rail pressure
²Boost pressure
Period of Actuation
For calculating the period of actuation of the main
injection it is necessary to know whether a pre-injec-
tion has occurred or not.
The coolant temperature, charge air temperature
and the atmospheric pressure are used for correcting
the main injection quantity. If main injection quan-
tity is less than a minimum quantity which is depen-
dent on fuel rail pressure, no preinjection takes
place. In this case, only main injection is performed.
If the quantity is then still below the minimum
quantity, neither main injection or pre-injection takes
place (deceleration mode).
Deceleration Mode
The purpose of the deceleration mode is to inter-
rupt the operation of the injectors. The ECM deter-
mines the accelerator pedal position from a supplied
signal and it determines the engine speed by the
crank sensor. In the overrun and with the engine
speed above 1600, with the accelerator pedal no
pressed, the injectors are no longer actuated and the
fuel rail pressure is lowered by the pressure regula-
tor valve.
Full Load Injected Quantity
The purpose of the full load injected quantity is to
minimize the formation of smoke. The ECM limits
the fuel rail pressure when the engine is operating at
full load by way of the quantity control valve, and
quantity of fuel injected by the injectors. this mini-
mizes the formation of smoke when accelerating and
driving at constant speeds. If a fault occurs at the
boost pressure control, full load injected quantity is
reduced.
Limiting Maximum Engine Speed
The ECM determines the engine speed based on
the signal supplied by the crankshaft sensor and lim-its this by interrupting the operation of the fuel
injectors.
Fuel Quantity Control
The fuel quantity is controlled separately for each
cylinder by the ECM inline with the firing order.The
ECM detects the operating state which exists at the
engine by means of the sensors. In order adapt the
quantity injected, either the fuel rail pressure can be
adjusted by the fuel solenoid and quantity control
valve or the actuation time of the solenoid valves in
the injectors
Boiling Protection
In order to protect against thermal overload and
along with criteria programmed in the ECM, the
injection quantity is reduced as a function of the cool-
ant temperature and vehicle speed. If the coolant
temperature sensor fails the oil temperature signal
from the oil sensor is used as a suitable value.
Fuel Tank Protection
The fuel rail pressure is lowered in order to protect
the fuel tank from overheating. The fuel temperature
sensor measures the temperature of the fuel being
supplied from the tank, in the high pressure flange.
If the fuel is too warm the fuel rail pressure is fur-
ther reduced by the quantity control valve.
STANDARD PROCEDURE
STANDARD PROCEDURE - DRAINING FUEL
TANK - DIESEL
(1) Position a drain hose into the fuel fill opening.
(2) Drain fuel tank using an approved diesel fuel
draining station.
FUEL CONTAMINATION
If a diesel engine's fuel supply has been contami-
nated with gasoline, the following procedure must be
followed:
(1) Remove all fuel from the fuel tank. (Refer to 14
- FUEL SYSTEM/FUEL DELIVERY - STANDARD
PROCEDURE-DRAINING FUEL TANK) Use an
appropriate fuel container. Dispose of the contami-
nated fuel using the proper procedures.
CAUTION: Dispose of petroleum based products in
a manner consistent with all applicable Local, State,
Federal, and Provincial regulations.
(2) Remove and clean fuel tank. (Refer to 14 -
FUEL SYSTEM/FUEL DELIVERY/FUEL TANK -
REMOVAL)
(3) Install the fuel tank. (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/FUEL TANK - INSTALLA-
TION)
14 - 8 FUEL DELIVERYVA
INSTALLATION
(1) Install the sealing ring onto the sensor and
screw the fuel pressure sensor into the fuel rail.
(2) Tighten the senor to 60 N´m (44 ft. lbs.), back
it off 90 degrees and retighten to 80 N´m (59 ft. lbs.)
(Fig. 4).
(3) Connect the sensor wiring harness connector.
CAUTION: Care must be taken when installing the
engine cover. Assure the proper routing of the fuel
injector return fuel hose to the banjo bolt fitting in
the left rear corner of the cover. Failure to do so
may pinch or damage the hose causing fuel leakage
or a driveability concern.
(4) (Refer to 14 - FUEL SYSTEM - WARNING).
Start engine, allow to run for a few minutes, turn the
engine off and inspect for leaks.
FUEL PUMP
DESCRIPTION
DESCRIPTION - HIGH PRESSURE PUMP
WARNING: (Refer to 14 - FUEL SYSTEM - WARN-
ING)
The high pressure pump is a fuel regulated radial
piston pump with three pistons arranged at an angle
of 120É. The regulation being carried out by the fuel
quantity valve. The high pressure pump is driven at
about 1.3 times the speed of the camshaft. Specific
moving parts inside the pump are graphite coated to
assist with the lubrication process during operation.
The high pressure pump is mounted to the front of
the cylinder head and must be replaced as an assem-
bly should a failure occur (Fig. 5).
DESCRIPTION - LOW PRESSURE PUMP
The electric fuel pump is located in the fuel tank.
The pump draws warm or hot fuel from the fuel tank
module bowl and also draws cool fuel out of the tank.
The cool fuel is drawn in and is mixed with the fuel
already in the bowl in a 50±50 mix ratio. Refer to
fuel pump module for servicing (Refer to 14 - FUEL
SYSTEM/FUEL DELIVERY/FUEL TANK MODULE
- REMOVAL).
OPERATION
OPERATION
LOW PRESSURE SIDE
The fuel supplied by the low pressure pump flows
through the fuel supply (5) at the high pressure
pump and is passed to the fuel quantity valve (11)
and the fuel pressure relief valve (9). Any air
entrained by the fuel is directed through the restric-
tor (10) through the bleed port (7) to the return flow
(6). The quantity control valve (11) controls the
amount of fuel that flows along the ring passage (4)
through the supply ports to the three high pressure
pump elements. To lubricate the plunger and barrel
assemblies when the quantity control valve is closed
Fig. 5 HIGH PRESSURE FUEL PUMP
1 - HIGH PRESSURE PUMP
2 - FUEL SUPPY TO FUEL RAIL
3 - FUEL SUPPLY LINE
4 - FUEL RETURN LINE
5 - FUEL TEMPERATURE SENSOR
6 - FUEL QUANTITY CONTROL VALVE
7 - OIL LEVEL INDICATOR
8 - VACUUM PUMP
VAFUEL DELIVERY 14 - 13
FUEL QUANTITY CONTROL
VA LV E
DESCRIPTION
The fuel quantity control valve mounts to front of
the high pressure pump and is controlled by the
ECM. The quantity control valve assists in maintain-
ing proper fuel quantity injected under all operating
conditions. Fuel tank heat protection is also provided
by the quantity control valve. The valve meters the
exact amount of fuel to prevent excess heated fuel
from returning to the tank.
OPERATION
The ECM monitors the fuel system and measures
for pressure vibrations. The ECM will then send a
pulse width signal to the quantity control valve to
regulate the amount of fuel to the high pressure
pump plunger and barrel assemblies. The valve then
adjusts the injection correction quantity for each
individual cylinder in line with the firing order, there
by eliminating the pressure resonance in the fuel rail
and improving each independent injectors operation.
The fuel quantity valve also interrupts the fuel sup-
ply to the high pressure pump plunger and barrel
assemblies when the engine is switched off.
The ECM detects the operating state which exists
at the engine by means of the sensors. In order to
adapt the quantity injected, either the rail pressure
can be adjusted by way of the pressure regulator
valve and the quantity control valve, or the actuationtime of the solenoid valves in the fuel injectors can
be extended or shortened.
Fuel quantity control is performed under the fol-
lowing operating conditions:
²Approximately 30 seconds after the engine has
started
²Fuel temperature > 20ÉC (68ÉF)
²Engine not in deceleration mode
REMOVAL
(1) Disconnect the negative battery cable.
(2) Disconnect the control valve wiring harness
connector (Fig. 18).
(3) Remove the valve fasteners and remove the
control valve (Fig. 18).
INSTALLATION
(1) Clean sealing surfaces.
(2) Install new seal on sensor.
(3) Position the control valve on to the high pres-
sure pump and install fasteners (Fig. 19).
(4) Connect wiring harness connector to control
valve (Fig. 19).
(5) Connect negative battery cable.
(6) Start the engine, allow to run, turn engine off
and inspect for leaks (Refer to 14 - FUEL SYSTEM/
FUEL INJECTION - WARNING).
Fig. 17 ALIGN PUMP MODULE
1 - LOCKNUT
2 - ALIGNMENT ARROW (POSITION TOWARDS RIGHT SIDE OF
VEHICLE)
Fig. 18 HIGH PRESSURE FUEL PUMP
1 - HIGH PRESSURE PUMP
2 - FUEL SUPPY TO FUEL RAIL
3 - FUEL SUPPLY LINE
4 - FUEL RETURN LINE
5 - FUEL TEMPERATURE SENSOR
6 - FUEL QUANTITY CONTROL VALVE
7 - OIL LEVEL INDICATOR
8 - VACUUM PUMP
VAFUEL DELIVERY 14 - 21
(5) Tighten fuel rail bolts to 14 N´m (124 in. lbs.)
(Fig. 19)
CAUTION: When tightening fuel injection line union
nuts, counter hold with a wrench at the thread con-
nection. ON NO ACCOUNT exceed the tightening
torque at any time.
(6) Tighten the pressure line to the fuel rail to 20
N´m (177 in. lbs.).
(7) Tighten the high pressure fuel lines at the fuel
rail to 22 N´m (195 in. lbs.).
(8) Reconnect engine harness electrical connectors.
(9) Connect the intake manifold air inlet duct.
(10) Connect negative battery cable.
CAUTION: Care must be taken when installing the
engine cover. Assure the proper routing of the fuel
injector return fuel hose to the banjo bolt fitting in
the left rear corner of the cover. Failure to do so
may pinch or damage the hose causing fuel leakage
or a driveability concern.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH FAN. DO NOT PUT YOUR
HANDS NEAR PULLEYS, BELTS OR FAN. DO NOT
WEAR LOOSE CLOTHING.
(11) Start engine, run for a few minutes, turn the
engine off and inspect for leaks (Refer to 14 - FUEL
SYSTEM - WARNING).
FUEL TANK
DESCRIPTION
The plastic fuel tank (Fig. 20) is mounted to the
frame rails under the left/center side of the vehicle.
The fuel tank contains a serviceable fuel pump mod-
ule with an electric fuel pump, and a fuel level send-
ing unit. The tank is also equipped with 2 fuel lines:
a fuel supply line to the fuel pump, and a separate
fuel return line.
Fuel Temperature Control:A section of the fuel
return line is coiled at the rear section of the tank
(Fig. 21). This coiled section is used to help drop the
temperature of fuel returning to the tank. A thermo-
stat (preheating valve) (3) (Fig. 21) is used to keep
fuel temperature below 167 degrees F. If fuel temper-
ature is above 167 degrees F, fuel passes first
through the coiled cooler lines, and then into the fuel
tank. If fuel temperature is below 150 degrees F, fuel
bypasses the coiled cooler lines, and is returned
directly into the fuel tank.
An electric fuel pump (more commonly referred to
in diesel applications as a fuel transfer pump or fuel
lift pump) is attached to the fuel pump module. Thismodule (Fig. 22) is located in the fuel tank. Refer to
Fuel Pump Module for additional information.
VAFUEL DELIVERY 14 - 23
INSTALLATION
(1) (Refer to 14 - FUEL SYSTEM/FUEL INJEC-
TION - WARNING) Install the sealing ring on to the
sensor (Fig. 14).
(2) Screw the sensor in to the fuel rail. Counter-
hold the threaded connection and tighten the sensor
to 18 lbs. ft. (25 N´m.) (Fig. 14).
(3) Connect the wiring harness to the sensor.
(4) Install the mixing housing.
CAUTION: Care must be taken when installing the
engine cover. Assure the proper routing of the fuel
injector return fuel hose to the banjo bolt fitting in
the left rear corner of the cover. Failure to do so
may pinch or damage the hose causing fuel leakage
or a driveability concern.
(5) Connect negative battery cable.
FUEL PRESSURE SOLENOID
DESCRIPTION
The fuel pressure solenoid is attached to the rear
of the fuel rail. A sealing metal disc seals the valve to
the rail. The seal is not serviceable and looses it's
sealing properties upon removal of the solenoid.
Therefore, the solenoid must be replaced when ever
it is removed from the rail. The solenoid controls and
maintains the rail pressure constant along with a
control current transmitted by the engine control
module (ECM) (Fig. 15).
OPERATION
High pressure which is present in the fuel rail
flows to the ball seat of the pressure solenoid (Fig.
16). The specified pressure required by the system is
built up in the rail by the fuel pressure solenoid
building up a magnetic force which corresponds to
this specific pressure by means of a control current
from the electronic control module (ECM) (Fig. 16).
This magnetic force equals a certain outlet cross sec-
tion at the ball seat of the valve. The rail pressure is
altered as a result of the quantity of fuel which flows
off (Fig. 16). The current fuel pressure is signaled by
the fuel rail pressure sensor to the engine control
module (ECM). The controlled fuel flows back along
the return fuel line, into the tank.
In a de-energized state, the fuel pressure solenoid
is closed as the spring force presses the ball into the
ball seat (Fig. 16). When driving, the fuel pressure
solenoid is constantly open (Fig. 16). When engine is
started, the fuel pressure solenoid is held closed by
magnetic force (Fig. 16). When driving, the pressure
of the fluid counteracts the magnetic force of the coil
and the slight spring force (Fig. 16).
Fig. 15 FUEL PRESSURE SOLENOID
1 - FUEL PRESSURE SENSOR
2 - FUEL RAIL
3 - FUEL PRESSURE SOLENOID
Fig. 16 FUEL PRESSURE SOLENOID OPERATION
1 - BALL SEAT
2 - SPRING FORCE
3 - MAGNETIC FORCE
4 - COIL
5 - FUEL PRESSURE SOLENOID
6 - HIGH PRESSURE SUPPLY
14 - 40 FUEL INJECTIONVA
²Tighten the nut to 60 N´m (44 ft. lbs.)
²Loosen the nut 90 degrees.
²Retighten the nut to 80 N´m (59 ft. lbs.).
(3) Install fuel rail (Refer to 14 - FUEL SYSTEM/
FUEL INJECTION/FUEL INJECTOR - INSTALLA-
TION).
(4) Connect negative battery cable.
(5) Start engine, allow to warm, turn engine off
and inspect for leaks (Refer to 14 - FUEL SYSTEM -
DIAGNOSIS AND TESTING).
FUEL TEMPERATURE SENSOR
DESCRIPTION
The fuel temperature sensor is integrated in the
high pressure fuel pump next to the fuel quantity
valve. The sensor detects the temperature of the fuel
and supplies that information to the ECM. The sen-
sor ranges from - 40ÉF (- 40C) to 284ÉF (140ÉC). If
the engine is cold, the actual value sent will read
ambient temperature. The value rises after the
engine has been started.
OPERATION
An negative temperature coefficient (NTC) resistor
integrated in the fuel temperature sensor alters it's
electrical resistance in line with the fuel temperature
(the resistance drops as the temperature rises). The
ECM uses this reading to calculate optimum engine
performance under all driving conditions. If the fuel
is to warm, the rail pressure in the system is low-
ered. The controller quantity of the pressure regulat-
ing valve is reduced and the fuel temperature is
lowered.
REMOVAL
NOTE: Capture and properly store all fluid seepage
in appropriately marked containers.
(1) Disconnect the negative battery cable.
(2) Remove the fuel temperature sensor from the
high pressure pump (Fig. 19).
INSTALLATION
(1) Clean sealing surfaces.
(2) Install new seal on sensor.
(3) Screw the sensor into the high pressure pump
and tighten to 18 lbs.ft. (25 N´m) (Fig. 19)
(4) Connect negative battery cable.
(5) Start engine, allow to warm, shut engine off
and inspect for leaks (Refer to 14 - FUEL SYSTEM/
FUEL INJECTION - WARNING).
INTAKE AIR TEMPERATURE
SENSOR
DESCRIPTION
The intake air temperature sensor is located
between the charge air pipe and the charge air dis-
tribution of the cylinders. The intake air temperature
sensor measures the temperature of the air as it is
supplied to the cylinders and transmits the value to
the ECM. This is required in order to determine the
density of the air being supplied for the combustion
process. The value range is from minus 40ÉF up to
302ÉF (minus 40ÉC to 150ÉC).
Fig. 19 HIGH PRESSURE FUEL PUMP
1 - HIGH PRESSURE PUMP
2 - FUEL SUPPY TO FUEL RAIL
3 - FUEL SUPPLY LINE
4 - FUEL RETURN LINE
5 - FUEL TEMPERATURE SENSOR
6 - FUEL QUANTITY CONTROL VALVE
7 - OIL LEVEL INDICATOR
8 - VACUUM PUMP
14 - 42 FUEL INJECTIONVA
STEERING
TABLE OF CONTENTS
page page
STEERING
DESCRIPTION..........................1
OPERATION............................1
DIAGNOSIS AND TESTING - POWER
STEERING SYSTEM....................1COLUMN................................4
GEAR..................................7
LINKAGE................................9
PUMP..................................11
STEERING
DESCRIPTION
CAUTION: Use approved fluid only in the power
steering system (Refer to LUBRICATION & MAINTE-
NANCE/FLUID TYPES - DESCRIPTION). No other
power steering or automatic transmission fluid is to
be used in the system. Damage may result to the
power steering pump and system if any other fluid
is used, and do not overfill.
Power steering systems consist of:
²Steering column
²Rack and pinion steering gear
²Belt driven hydraulic steering pump
²Pump pressure and return hoses
²Oil Cooler
OPERATION
The steering column shaft is attached to the gear
pinion. The rotation of the pinion moves the gear
rack from side-to-side. This lateral action of the rack
pushes and pulls the tie rods to change the direction
of the front wheels (Fig. 1).
Power assist is provided by an engine mounted
hydraulic pump which supplies hydraulic fluid pres-
sure to the steering gear.
DIAGNOSIS AND TESTING - POWER STEERING
SYSTEM
There is some noise in all power steering systems.
One of the most common is a hissing sound evident at
a standstill parking. Or when the steering wheel is at
the end of it's travel. Hiss is a high frequency noise
similar to that of a water tap being closed slowly. The
noise is present in all valves that have a high velocity
fluid passing through an orifice. There is no relation-
ship between this noise and steering performance.
Fig. 1 STEERING COMPONENTS
1 - POWER STEERING PUMP ASSEMBLY
2 - RESERVOIR
3 - HOSES
4 - TIE ROD ENDS
5 - MOUNTING BOLTS
6 - RACK & PINION
VASTEERING 19 - 1
(4) Slowly turn the steering wheel lock-to-lock 20
times with the engine off while checking the fluid
level.
NOTE: For vehicles with long return lines or oil
coolers turn wheel 40 times.
(5) Start the engine. With the engine idling main-
tain the fluid level.
(6) Lower the front wheels and let the engine idle
for two minutes.
(7) Turn the steering wheel in both direction and
verify power assist and quiet operation of the pump.
If the fluid is extremely foamy or milky looking,
allow the vehicle to stand a few minutes and repeat
the procedure.
CAUTION: Do not run a vehicle with foamy fluid for
an extended period. This may cause pump damage.
STANDARD PROCEDURE - FLUSHING POWER
STEERING SYSTEM
Flushing is required when the power steering/hy-
draulic booster system fluid has become contami-
nated. Contaminated fluid in the steering/booster
system can cause seal deterioration and affect steer-
ing gear/booster spool valve operation.
(1) Raise the front end of the vehicle off the
ground until the wheels are free to turn.
(2) Remove the return line from the pump.
NOTE: If vehicle is equipped with a hydraulic
booster remove both return lines from the pump.
(3) Plug the return line port/ports at the pump.
(4) Position the return line/lines into a large con-
tainer to catch the fluid.
(5) While an assistant is filling the pump reservoir
start the engine.
(6) With the engine running at idle turn the wheel
back and forth.
NOTE: Do not contact or hold the wheel against the
steering stops.
(7) Run a quart of fluid through the system then
stop the engine and install the return line/lines.
(8) Fill the system with fluid and perform Steering
Pump Initial Operation, (Refer to 19 - STEERING/
PUMP - STANDARD PROCEDURE).
(9) Start the engine and run it for fifteen minutes
then stop the engine.
(10) Remove the return line/lines from the pump
and plug the pump port/ports.
(11) Pour fresh fluid into the reservoir and check
the draining fluid for contamination. If the fluid is
still contaminated, then flush the system again.(12) Install the return line/lines and perform
Steering Pump Initial Operation, (Refer to 19 -
STEERING/PUMP - STANDARD PROCEDURE).
REMOVAL
(1) Remove the belt from the power steering pump.
(2) Siphon as much power steering fluid as possi-
ble out of the reservoir.
(3) Remove the high pressure power steering hose
at the pump (Fig. 1).
(4) Remove the return hose from the pump (Fig.
1).
(5) Remove the bolts securing the power steering
pump to the engine (Fig. 1).
INSTALLATION
(1) Install the power steering pump to the engine
and tighten the bolts (Fig. 1). Tighten to 21 N´m (15
ft. lbs.).
(2) Replace all o-rings and hose clamps (Fig. 1).
(3) Install the return hose to the pump and tighten
the clamp (Fig. 1).
(4) Install the high pressure hose to the pump
(Fig. 1). Tighten to 38 N´m (28 ft. lbs.).
(5) Fill the power steering fluid (Refer to 19 -
STEERING/PUMP/FLUID - STANDARD PROCE-
DURE).
Fig. 1 POWER STEERING PUMP
1 - PUMP MOUNTING BOLT
2 - CLAMP
3 - RETURN HOSE
4 - HIGH PRESSURE HOSE
5 - O-RING
6 - PUMP RESERVOIR
7 - PUMP
8 - PULLEY
9 - PULLEY BOLT
19 - 12 PUMPVA