relay DODGE RAM 2001 Service Repair Manual

(3) Install MAP sensor mounting bolts (screws).
Tighten screws to 3 N´m (25 in. lbs.) torque.
(4) Install air cleaner.
INSTALLATION - 8.0L
The MAP sensor is mounted into the right upper
side of the intake manifold (Fig. 38). A rubber gasket
is used to seal the sensor to the intake manifold. The
rubber gasket is part of the sensor and is not ser-
viced separately.
(1) Check the condition of the sensor seal. Clean
the sensor and lubricate the rubber gasket with clean
engine oil.
(2) Clean the sensor opening in the intake mani-
fold.
(3) Install the sensor into the intake manifold.
(4) Install sensor mounting bolts. Tighten bolts to
2 N´m (20 in. lbs.) torque.
(5) Install the electrical connector to sensor.
O2 SENSOR
DESCRIPTION
The Oxygen Sensors (O2S) are attached to, and
protrude into the vehicle exhaust system. Depending
on the emission package, the vehicle may use a total
of either 2 or 4 sensors.
3.9L/5.2L/Light Duty 5.9L Engine:Four sensors
are used: 2 upstream (referred to as 1/1 and 2/1) and
2 downstream (referred to as 1/2 and 2/2). With this
emission package, the right upstream sensor (2/1) is
located in the right exhaust downpipe just before the
mini-catalytic convertor. The left upstream sensor
(1/1) is located in the left exhaust downpipe just
before the mini-catalytic convertor. The right down-
stream sensor (2/2) is located in the right exhaust
downpipe just after the mini-catalytic convertor, and
before the main catalytic convertor. The left down-
stream sensor (1/2) is located in the left exhaust
downpipe just after the mini-catalytic convertor, and
before the main catalytic convertor.
Medium and Heavy Duty 8.0L V-10 Engine:
Four sensors are used (2 upstream, 1 pre-catalyst
and 1 post-catalyst). With this emission package, the
1/1 upstream sensor (left side) is located in the left
exhaust downpipe before both the pre-catalyst sensor
(1/2), and the main catalytic convertor. The 2/1
upstream sensor (right side) is located in the right
exhaust downpipe before both the pre-catalyst sensor
(1/2), and the main catalytic convertor. The pre-cata-
lyst sensor (1/2) is located after the 1/1 and 2/1 sen-
sors, and just before the main catalytic convertor.
The post-catalyst sensor (1/3) is located just after the
main catalytic convertor.Heavy Duty 5.9L Engine:Two sensors are used.
They arebothreferred to as upstream sensors (left
side is referred to as 1/1 and right side is referred to
as 2/1). With this emission package, a sensor is
located in each of the exhaust downpipes before the
main catalytic convertor.
OPERATION
An O2 sensor is a galvanic battery that provides
the PCM with a voltage signal (0-1 volt) inversely
proportional to the amount of oxygen in the exhaust.
In other words, if the oxygen content is low, the volt-
age output is high; if the oxygen content is high the
output voltage is low. The PCM uses this information
to adjust injector pulse-width to achieve the
14.7±to±1 air/fuel ratio necessary for proper engine
operation and to control emissions.
The O2 sensor must have a source of oxygen from
outside of the exhaust stream for comparison. Cur-
rent O2 sensors receive their fresh oxygen (outside
air) supply through the wire harness. This is why it
is important to never solder an O2 sensor connector,
or pack the connector with grease.
Four wires (circuits) are used on each O2 sensor: a
12±volt feed circuit for the sensor heating element; a
ground circuit for the heater element; a low-noise
sensor return circuit to the PCM, and an input cir-
cuit from the sensor back to the PCM to detect sen-
sor operation.
Oxygen Sensor Heaters/Heater Relays:
Depending on the emissions package, the heating ele-
ments within the sensors will be supplied voltage
from either the ASD relay, or 2 separate oxygen sen-
sor relays. Refer to 8, Wiring Diagrams to determine
which relays are used.
The O2 sensor uses a Positive Thermal Co-efficient
(PTC) heater element. As temperature increases,
resistance increases. At ambient temperatures
around 70ÉF, the resistance of the heating element is
approximately 4.5 ohms. As the sensor's temperature
increases, resistance in the heater element increases.
This allows the heater to maintain the optimum
operating temperature of approximately 930É-1100ÉF
(500É-600É C). Although the sensors operate the
same, there are physical differences, due to the envi-
ronment that they operate in, that keep them from
being interchangeable.
Maintaining correct sensor temperature at all times
allows the system to enter into closed loop operation
sooner. Also, it allows the system to remain in closed
loop operation during periods of extended idle.
In Closed Loop operation, the PCM monitors cer-
tain O2 sensor input(s) along with other inputs, and
adjusts the injector pulse width accordingly. During
Open Loop operation, the PCM ignores the O2 sensor
input. The PCM adjusts injector pulse width based
14 - 46 FUEL INJECTION - GASOLINEBR/BE
MANIFOLD ABSOLUTE PRESSURE SENSOR (Continued)

FUEL INJECTOR
DESCRIPTION
A separate fuel injector (Fig. 51) is used for each
individual cylinder.
OPERATION
The fuel injectors are electrical solenoids. The
injector contains a pintle that closes off an orifice at
the nozzle end. When electric current is supplied to
the injector, the armature and needle move a short
distance against a spring, allowing fuel to flow out
the orifice. Because the fuel is under high pressure, a
fine spray is developed in the shape of a pencil
stream. The spraying action atomizes the fuel, add-
ing it to the air entering the combustion chamber.
An individual fuel injector is used for each individ-
ual cylinder. The top (fuel entry) end of the injector is
attached into an opening on the fuel rail.
The nozzle (outlet) ends of the injectors are posi-
tioned into openings in the intake manifold just above
the intake valve ports of the cylinder head. The engine
wiring harness connector for each fuel injector is
equipped with an attached numerical tag (INJ 1, INJ 2
etc.). This is used to identify each fuel injector.
The injectors are energized individually in a
sequential order by the Powertrain Control Module
(PCM). The PCM will adjust injector pulse width by
switching the ground path to each individual injector
on and off. Injector pulse width is the period of time
that the injector is energized. The PCM will adjust
injector pulse width based on various inputs it
receives.
Battery voltage is supplied to the injectors through
the ASD relay.
The PCM determines injector pulse width based on
various inputs.
OPERATION - PCM OUTPUT
The nozzle ends of the injectors are positioned into
openings in the intake manifold just above the intake
valve ports of the cylinder head. The engine wiring
harness connector for each fuel injector is equipped
with an attached numerical tag (INJ 1, INJ 2 etc.).
This is used to identify each fuel injector with its
respective cylinder number.
The injectors are energized individually in a
sequential order by the Powertrain Control Module
(PCM). The PCM will adjust injector pulse width by
switching the ground path to each individual injector
on and off. Injector pulse width is the period of time
that the injector is energized. The PCM will adjust
injector pulse width based on various inputs it
receives.
Battery voltage (12 volts +) is supplied to the injec-
tors through the ASD relay. The ASD relay will shut-
down the 12 volt power source to the fuel injectors if
the PCM senses the ignition is on, but the engine is
not running. This occurs after the engine has not
been running for approximately 1.8 seconds.
The PCM determines injector on-time (pulse width)
based on various inputs.
DIAGNOSIS AND TESTING - FUEL INJECTOR
TEST
To perform a complete test of the fuel injectors and
their circuitry, use the DRB scan tool and refer to the
appropriate Powertrain Diagnostics Procedures man-
ual. To test the injector only, refer to the following:
Disconnect the fuel injector wire harness connector
from the injector. The injector is equipped with 2
electrical terminals (pins). Place an ohmmeter across
the terminals. Resistance reading should be approxi-
mately 12 ohms61.2 ohms at 20ÉC (68ÉF).
REMOVAL
(1) Remove air cleaner assembly.
(2) Remove fuel injector rail assembly. Refer to
Fuel Injector Rail removal in this section.
(3) Remove the clip(s) retaining the injector(s) to
fuel rail (Fig. 30) or (Fig. 31).
(4) Remove injector(s) from fuel rail.
INSTALLATION
(1) Apply a small amount of engine oil to each fuel
injector o-ring. This will help in fuel rail installation.
(2) Install injector(s) and injector clip(s) to fuel
rail.
(3) Install fuel rail assembly. Refer to Fuel Injector
Rail installation.
(4) Install air cleaner.
(5) Start engine and check for leaks.
Fig. 51 Fuel Injector
1 - FUEL INJECTOR
2 - NOZZLE
3 - TOP (FUEL ENTRY)
BR/BEFUEL INJECTION - GASOLINE 14 - 53

FUEL DELIVERY - DIESEL
TABLE OF CONTENTS
page page
FUEL DELIVERY - DIESEL
DESCRIPTION...........................54
OPERATION.............................56
DIAGNOSIS AND TESTING.................56
AIR IN FUEL SYSTEM...................56
FUEL SUPPLY RESTRICTIONS............56
STANDARD PROCEDURE..................56
WATER DRAINING AT FUEL FILTER........56
CLEANING FUEL SYSTEM PARTS..........57
AIR BLEED............................57
SPECIFICATIONS........................58
SPECIAL TOOLS.........................59
FUEL FILTER / WATER SEPARATOR
DESCRIPTION...........................59
OPERATION.............................59
REMOVAL..............................60
INSTALLATION...........................61
FUEL HEATER
DESCRIPTION...........................62
OPERATION.............................62
DIAGNOSIS AND TESTING.................62
FUEL HEATER.........................62
REMOVAL..............................63
FUEL HEATER RELAY
DESCRIPTION...........................63
OPERATION.............................63
DIAGNOSIS AND TESTING.................64
FUEL HEATER RELAY...................64
REMOVAL..............................65
INSTALLATION...........................65
FUEL INJECTION PUMP
DESCRIPTION...........................65
OPERATION.............................66
DIAGNOSIS AND TESTING.................66
FUEL INJECTION PUMP TIMING...........66
REMOVAL..............................68
INSTALLATION...........................71
FUEL INJECTION PUMP DATA PLATE
SPECIFICATIONS........................73FUEL LEVEL SENDING UNIT / SENSOR
DESCRIPTION...........................73
OPERATION.............................73
FUEL LINES
DESCRIPTION...........................73
OPERATION.............................74
DIAGNOSIS AND TESTING.................74
HIGH-PRESSURE FUEL LINE LEAK.........74
REMOVAL..............................75
INSTALLATION...........................77
FUEL TANK
DESCRIPTION...........................78
FUEL TANK MODULE
DESCRIPTION...........................78
OPERATION.............................78
REMOVAL..............................78
INSTALLATION...........................79
FUEL TRANSFER PUMP
DESCRIPTION...........................79
OPERATION.............................79
DIAGNOSIS AND TESTING.................80
FUEL TRANSFER PUMP PRESSURE........80
REMOVAL..............................83
INSTALLATION...........................83
OVERFLOW VALVE
DESCRIPTION...........................83
OPERATION.............................83
DIAGNOSIS AND TESTING.................84
OVERFLOW VALVE.....................84
REMOVAL..............................84
INSTALLATION...........................85
WATER IN FUEL SENSOR
DESCRIPTION...........................85
OPERATION.............................85
REMOVAL..............................85
FUEL DRAIN MANIFOLD
DESCRIPTION...........................86
OPERATION.............................86
REMOVAL..............................86
INSTALLATION...........................86
FUEL DELIVERY - DIESEL
DESCRIPTION - DIESEL FUEL DELIVERY
SYSTEM
The fuel system on the Cummins 24 valveÐTurbo
Diesel Engine uses anelectronicfuel injection
pump with three control modules.Also refer to the Powertrain Control Module (PCM)
or Engine Control Module sections.
Some fuel system components are shown in (Fig.
1).
The fuel delivery system consists of the:
²Accelerator pedal
²Air cleaner housing/element
²Fuel drain manifold (passage)
14 - 54 FUEL DELIVERY - DIESELBR/BE

²Fuel filter/water separator
²Fuel heater
²Fuel heater relay
²Fuel transfer (lift) pump
²Fuel injection pump
²Fuel injectors
²Fuel heater temperature sensor
²Fuel tank
²Fuel tank filler/vent tube assembly
²Fuel tank filler tube cap
²Fuel tank module containing the rollover valve,
fuel gauge sending unit (fuel level sensor) and a sep-
arate fuel filter located at bottom of tank module
²Fuel tubes/lines/hoses
²High-pressure fuel injector lines
²In-tank fuel filter (at bottom of fuel tank mod-
ule)
²Low-pressure fuel supply lines
²Low-pressure fuel return line
²Overflow valve
²Quick-connect fittings
²Throttle cable
²Water draining
OPERATION
WARNING: HIGH-PRESSURE FUEL LINES DELIVER
DIESEL FUEL UNDER EXTREME PRESSURE FROM
THE INJECTION PUMP TO THE FUEL INJECTORS.
THIS MAY BE AS HIGH AS 120,000 KPA (17,405
PSI). USE EXTREME CAUTION WHEN INSPECTING
FOR HIGH-PRESSURE FUEL LEAKS. INSPECT FOR
HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF
CARDBOARD. HIGH FUEL INJECTION PRESSURE
CAN CAUSE PERSONAL INJURY IF CONTACT IS
MADE WITH THE SKIN.
DIAGNOSIS AND TESTING - AIR IN FUEL
SYSTEM
Air will enter the fuel system whenever fuel supply
lines, separator filters, injection pump, high-pressure
lines or injectors are removed or disconnected. Air
trapped in the fuel system can result in hard start-
ing, a rough running engine, engine misfire, low
power, excessive smoke and fuel knock. After service
is performed, air must be bled from the system
before starting the engine.Inspect the fuel system from the fuel transfer
pump to the injectors for loose connections. Leaking
fuel is an indicator of loose connections or defective
seals. Air can also enter the fuel system between the
fuel tank and the transfer pump. Inspect the fuel
tank and fuel lines for damage that might allow air
into the system.
For air bleeding, refer to the Air Bleed Procedure.
DIAGNOSIS AND TESTING - FUEL SUPPLY
RESTRICTIONS
LOW-PRESSURE LINES
Fuel supply line restrictions or a defective fuel
transfer pump can cause starting problems and pre-
vent engine from accelerating. The starting problems
include; low power and/or white fog like exhaust.
Test all fuel supply lines for restrictions or block-
age. Flush or replace as necessary. Bleed fuel system
of air once a fuel supply line has been replaced. Refer
to Air Bleed Procedure for procedures.
To test for fuel line restrictions, a vacuum restric-
tion test may be performed. Refer to Fuel Transfer
Pump Pressure Test.
HIGH-PRESSURE LINES
Restricted (kinked or bent) high-pressure lines can
cause starting problems, poor engine performance,
engine mis-fire and white smoke from exhaust.
Examine all high-pressure lines for any damage.
Each radius on each high-pressure line must be
smooth and free of any bends or kinks.
Replace damaged, restricted or leaking high-pres-
sure fuel lines with correct replacement line.
CAUTION: All high-pressure fuel lines must be
clamped securely in place in holders. Lines cannot
contact each other or other components. Do not
attempt to weld high-pressure fuel lines or to repair
lines that are damaged. If line is kinked or bent, it
must be replaced. Use only recommended lines
when replacement of high-pressure fuel line is nec-
essary.
STANDARD PROCEDURES - WATER DRAINING
AT FUEL FILTER
Refer to Fuel Filter/Water Separator removal/in-
stallation for procedures.
14 - 56 FUEL DELIVERY - DIESELBR/BE
FUEL DELIVERY - DIESEL (Continued)

(e) Connect electrical connector to WIF sensor.
(f) Install fuel filter. Refer to previous steps.
(4)Fuel Heater Element:
(a) Do not install fuel filter until heater element
is installed.
(b) Position heater element into filter housing
(fingers downward). Lock fingers into housing.
(c) Install new o-ring to electrical connector
(where connector passes through filter housing).
Apply a light film of clean diesel oil to o-ring seal.
Press this connector into filter housing until it
snaps into heater element.
(d) Install temperature sensor housing and 2
mounting screws to fuel filter housing.
(e) Connect electrical connector.
(f) Install fuel filter. Refer to previous steps.
(5)Drain Valve:
(a) Install 2 new o-rings to valve and filter hous-
ing.
(b) Apply a light film of clean diesel oil to both
seals.
(c) Position valve to filter housing.
(d) Install 4 mounting screws and tighten to 3±5
N´m (30±40 in. lbs.) torque.
(e) Connect drain hose to drain valve.
(f) Install fuel filter. Refer to previous steps.
(6) Start engine and check for leaks.
FUEL HEATER
DESCRIPTION
The fuel heater assembly is located on the side of
the fuel filter housing (Fig. 9).
The heater/element assembly is equipped with a
temperature sensor (thermostat) that senses fuel
temperature. This sensor is attached to the fuel heat-
er/element assembly.
OPERATION
The fuel heater is used to prevent diesel fuel from
waxing during cold weather operation.
When the temperature is below 4568 degrees F,
the temperature sensor allows current to flow to the
heater element warming the fuel. When the temper-
ature is above 7568 degrees F, the sensor stops cur-
rent flow to the heater element.
Battery voltage to operate the fuel heater element
is supplied from the ignition switch and through the
fuel heater relay. Also refer to Fuel Heater Relay.
The fuel heater element and fuel heater relay
are not computer controlled.
The heater element operates on 12 volts, 300 watts
at 0 degrees F.
DIAGNOSIS AND TESTING - FUEL HEATER
The fuel heater is used to prevent diesel fuel from
waxing during cold weather operation.
NOTE: The fuel heater element, fuel heater relay
and fuel heater temperature sensor are not con-
trolled by the Powertrain Control Module (PCM).
A malfunctioning fuel heater can cause a wax
build-up in the fuel filter/water separator. Wax
build-up in the filter/separator can cause engine
starting problems and prevent the engine from rev-
ving up. It can also cause blue or white fog-like
exhaust. If the heater is not operating in cold tem-
peratures, the engine may not operate due to fuel
waxing.
The fuel heater assembly is located on the side of
the fuel filter housing (Fig. 10).
The heater assembly is equipped with a built-in
fuel temperature sensor (thermostat) that senses fuel
temperature. When fuel temperature drops below 45
degrees68 degrees F, the sensor allows current to
flow to the built-in heater element to warm the fuel.
When fuel temperature rises above 75 degrees68
degrees F, the sensor stops current flow to the heater
element (circuit is open).
Fig. 9 Fuel Heater Location
1 - FUEL HEATER AND TEMP. SENSOR
2 - FUEL FILTER/WATER SEPARATOR
3 - FUEL HEATER ELECTRICAL CONNECTOR
14 - 62 FUEL DELIVERY - DIESELBR/BE
FUEL FILTER / WATER SEPARATOR (Continued)

Voltage to operate the fuel heater element is sup-
plied from the ignition switch, through the fuel
heater relay (also refer to Fuel Heater Relay), to the
fuel temperature sensor and on to the fuel heater ele-
ment.
The heater element operates on 12 volts, 300 watts
at 0 degrees F. As temperature increases, power
requirements decrease.
A minimum of 7 volts is required to operate the
fuel heater. The resistance value of the heater ele-
ment is less than 1 ohm (cold) and up to 1000 ohms
warm.
TESTING
(1) Disconnect electrical connector at sensor (Fig.
10).
Turn key to ON position. 12 volts should be
present at red wire. If not, check fuel heater relay
and related wiring. Refer to Relay TestÐFuel Heater.
If OK, proceed.
Turn key OFF. Check black wire in connector for
ground continuity with an ohmmeter. If continuity is
not present, correct open ground circuit. This test can
also be performed with a voltmeter by backprobing
black wire with it connected to sensor. Reconnect
electrical connector and turn key ON. Voltage drop
should not exceed 2 volts (2 volts lower than checked
at 12V+ connector). If voltage is lower, check for dirtyor corroded ground connection and repair. If OK, pro-
ceed.
(2) With electrical connector disconnected at sen-
sor and key OFF, check electrical/mechanical opera-
tion of fuel temperature sensor. Proceed to next step:
(3) Using an ohmmeter, check for continuity across
two terminals in electrical connector at side of sen-
sor. Sensor circuit should be open if fuel temperature
has risen above 75 degrees68 degrees F. Sensor cir-
cuit should be closed if fuel temperature has dropped
below 45 degrees68 degrees F. If not, replace fuel
heater assembly. This same test can also be per-
formed using a voltmeter, with key ON, and by back-
probing connector.
REMOVAL/INSTALLATION
The fuel heater/element/sensor assembly is located
inside of the fuel filter housing. Refer to Fuel Filter/
Water Separator Removal/Installation for procedures.
FUEL HEATER RELAY
DESCRIPTION
The fuel heater relay is located in Power Distribu-
tion Center (PDC) (Fig. 11). Refer to label on inside
of PDC cover for relay location.
OPERATION
Battery voltage to operate the fuel heater element
is supplied from the ignition switch through the fuel
heater relay.The fuel heater element and fuel
heater relay are not computer controlled.
Fig. 10 Fuel Heater Location
1 - FUEL HEATER AND TEMP. SENSOR
2 - FUEL FILTER/WATER SEPARATOR
3 - FUEL HEATER ELECTRICAL CONNECTOR
Fig. 11 Power Distribution Center Location
1 - CLIP
2 - BATTERY
3 - TRAY
4 - NEGATIVE CABLE
5 - POSITIVE CABLE
6 - CLIP
7 - FENDER INNER SHIELD
8 - POWER DISTRIBUTION CENTER
BR/BEFUEL DELIVERY - DIESEL 14 - 63
FUEL HEATER (Continued)

DIAGNOSIS AND TESTING - FUEL HEATER
RELAY
The fuel heater relay is located in the Power Dis-
tribution Center (PDC). Refer to label under PDC
cover for relay location.
To test the fuel heater, refer to Fuel Heater Test.
To test the heater relay only, refer to following:
The relay terminal numbers from (Fig. 12) can be
found on the bottom of the relay.
²Terminal number 30 is connected to battery volt-
age and can be switched or B+ (hot) at all times.
²The center terminal number 87A is connected (a
circuit is formed) to terminal 30 in the de-energized
(normally OFF) position.
²Terminal number 87 is connected (a circuit is
formed) to terminal 30 in the energized (ON) posi-
tion. Terminal number 87 then supplies battery volt-
age to the component being operated.
²Terminal number 86 is connected to a switched
(+) power source.
²Terminal number 85 is grounded by the power-
train control module (PCM).
TESTING
(1) Remove relay before testing.
(2) Using an ohmmeter, perform a resistance test
between terminals 85 and 86. Resistance value
(ohms) should be 7565 ohms for resistor equipped
relays.
(3) Connect the ohmmeter between terminals num-
ber 87A and 30. Continuity should be present at this
time.
(4) Connect the ohmmeter between terminals num-
ber 87 and 30. Continuity should not be present at
this time.
(5) Use a set of jumper wires (16 gauge or small-
er). Connect one jumper wire between terminal num-
ber 85 (on the relay) to the ground side (-) of a 12
Volt power source.
(6) Attach the other jumper wire to the positive
side (+) of a 12V power source. Do not connect this
jumper wire to relay at this time.
Fig. 12 Relay Terminals
14 - 64 FUEL DELIVERY - DIESELBR/BE
FUEL HEATER RELAY (Continued)

CAUTION: Do not allow the ohmmeter to contact
terminals 85 or 86 during these tests. Damage to
ohmmeter may result.
(7) Attach the other jumper wire (12V +) to termi-
nal number 86. This will activate the relay. Continu-
ity should now be present between terminals number
87 and 30. Continuity should not be present between
terminals number 87A and 30.
(8) Disconnect jumper wires from relay and 12 Volt
power source.
(9) If continuity or resistance tests did not pass,
replace relay. If tests passed, refer to 8, Wiring Dia-
grams for (fuel system) relay wiring schematics and
for additional circuit information.
REMOVAL
The fuel heater relay is located in the Power Dis-
tribution Center (PDC) (Fig. 13). Refer to label under
PDC cover for relay location.
(1) Remove PDC cover.
(2) Remove relay from PDC.
(3) Check condition of relay terminals and PDC
connector terminals for damage or corrosion. Repair
if necessary before installing relay.
(4) Check for pin height (pin height should be the
same for all terminals within the PDC connector).
Repair if necessary before installing relay.
INSTALLATION
The fuel heater relay is located in the Power Dis-
tribution Center (PDC) (Fig. 13). Refer to label under
PDC cover for relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
FUEL INJECTION PUMP
DESCRIPTIONÐFUEL PUMP 245 H.P.
Although the fuel injection pump on the 245 horse-
power engine appears similar to other VP 44 injec-
tion pumps, there are internal differences that make
it unique. If pump replacement is necessary, be sure
to verify pump number. The pump number can be
found on the Fuel Injection Pump Data Plate (Fig.
14).
Fig. 13 Power Distribution Center (PDC) Location
1 - CLIP
2 - BATTERY
3 - TRAY
4 - NEGATIVE CABLE
5 - POSITIVE CABLE
6 - CLIP
7 - FENDER INNER SHIELD
8 - POWER DISTRIBUTION CENTER
Fig. 14 Fuel Injection Pump Data Plate Location
1 - PUMP DATA PLATE
BR/BEFUEL DELIVERY - DIESEL 14 - 65
FUEL HEATER RELAY (Continued)

Refer to Fuel Transfer Pump Description/Operation
for an operational description of transfer pump.
The fuel transfer (lift) pump is located on left side
of engine and above starter motor (Fig. 53).
An improperly operating fuel transfer pump, a
plugged or dirty fuel filter, or a defective overflow
valve can cause low engine power, excessive white
smoke and/or hard engine starting.
Before performing following tests, inspect fuel sup-
ply and return lines for restrictions, kinks or leaks.
Fuel leaking from pump casing indicates a leaking
pump which must be replaced.
Pressure Test:Because the transfer pump is oper-
ating at two different pressure cycles (engine running
and engine cranking), two different pressure tests
will be performed.
(1) Remove protective cap at inlet test port (Fig.
54). Clean area around cap/fitting before cap
removal.
(2) Remove protective cap at outlet test port (Fig.
55). Clean area around cap/fitting before cap
removal.
(3) Install Special Fuel Pressure Test Gauge 6828
(or equivalent) to fitting at inlet test port (Fig. 54).(4) To prevent engine from starting, remove fuel
system relay (fuel injection pump relay). Relay is
located in Power Distribution Center (PDC). Refer to
label under PDC cover for relay location.
Fig. 53 Fuel Transfer Pump Location
1 - OIL PRESSURE SENSOR
2 - PUMP BRACKET NUTS (3)
3 - SUPPORT BRACKET BOLT
4 - BANJO BOLT (REAR)
5 - FUEL SUPPLY LINE
6 - ELECTRICAL CONNECTOR
7 - BANJO BOLT (FRONT)
8 - FUEL TRANSFER PUMP
Fig. 54 Fuel Pressure Test Port Fitting (Inlet)
1 - FUEL PRESSURE TEST PORT (INLET)
2 - FUEL FILTER/WATER SEPARATOR
Fig. 55 Fuel Pressure Test Port Fitting (Outlet)
1 - FUEL PRESSURE TEST PORT (OUTLET)
BR/BEFUEL DELIVERY - DIESEL 14 - 81
FUEL TRANSFER PUMP (Continued)

(5) Using key, crank engine over while observing
gauge. Pressure should be 5±7 psi.
(6) Re-install fuel system relay to PDC.
(7) Start engine and record fuel pressure. Pressure
should be aminimumof 69 kPa (10 psi) at idle
speed.
(8) Because fuel pump relay was removed, a Diag-
nostic Trouble Code (DTC) may have been set. After
testing is completed, and relay has been installed,
use DRB scan tool to remove DTC.
Pressure Drop Test:
(9) Shut engine off and remove test gauge from
inlet port test fitting. Re-attach 6828 test gauge to
outlet port (Fig. 55). Start engine and record fuel
pressure. Pressure should not be more than 34 kPa
(5 psi) lower than inlet port pressure test. If so,
replace fuel filter.
Fuel Supply Restriction Test:
Due to very small vacuum specifications, the DRB
scan tool along with the Periphal Expansion Port
(PEP) Module and 0±15 psi transducer must be used.
(10) Verify transfer pump pressure is OK before
performing restriction test.
(11) Locate and disconnect fuel supply line quick-
connect fitting at left-rear of engine (Fig. 56). After
disconnecting line, plastic clip will remain attached
to metal fuel line at engine. Carefully remove clip
from metal line. Snap same clip into fuel supply
hose.
(12) Install Special Rubber Adapter Hose Tool
6631 (3/8º) into ends of disconnected fuel supply line.(13) Install transducer from PEP module to brass
ªTº fitting on tool 6631.
(14) Hook up DRB scan tool to transducer.
WARNING: DO NOT STAND IN LINE WITH THE
COOLING FAN FOR THE FOLLOWING STEPS.
(15) Start engine and record vacuum reading with
engine speed at high-idle (high-idle means engine
speed is at 100 percent throttle and no load). The
fuel restriction testMUSTbe done with engine speed
at high-idle.
(16) If vacuum reading islessthan 6 in/hg. (0±152
mm hg.), test is OK. If vacuum reading ishigher
than 6 in/hg. (152 mm hg.), restriction exists in fuel
supply line or in fuel tank module. Check fuel supply
line for damage, dents or kinking. If OK, remove
module and check module and lines for blockage.
Also check fuel pump inlet filter at bottom of module
for obstructions.
Testing For Air Leaks in Fuel Supply Side:
(17) A 3±foot section of 3/8º I.D. clear tubing is
required for this test.
(18) Using a tire core valve removal tool, carefully
remove core valve from inlet fitting test port.
(19) Attach and clamp the 3/8ºclear hose to fitting
nipple.
(20) Place other end of hose into a large clear con-
tainer. Allow hose to loop as high as possibleabove
test port.
(21) The fuel transfer pump can be put into a 25
second run (test) mode if key is quickly turned to
crank position and released back to run position
without starting engine.
To prevent engine from starting in this test, first
remove fuel system relay (fuel injection pump relay).
Relay is located in Power Distribution Center (PDC).
Refer to label under PDC cover for relay location.
Because fuel pump relay was removed, a Diagnos-
tic Trouble Code (DTC) may have been set. After test-
ing is completed, and relay has been installed, use
DRB scan tool to remove DTC.
(22) Allow air to purge from empty hose before
examining for air bubbles. Air bubbles should not be
present.
(23) If bubbles are present, check for leaks in sup-
ply line to fuel tank.
(24) If supply line is not leaking, remove fuel tank
module and remove filter at bottom of module (filter
snaps to module). Check for leaks between supply
nipple at top of module, and filter opening at bottom
of module. Replace module if necessary.
(25) After performing test, install core back into
test fitting. Before installing protective cap, be sure
fitting is not leaking.
Fig. 56 Fuel Return and Supply Line Quick-Connect
Locations
1 - FUEL RETURN LINE
2 - QUICK-CONNECT FITTINGS
3 - FUEL SUPPLY LINE
14 - 82 FUEL DELIVERY - DIESELBR/BE
FUEL TRANSFER PUMP (Continued)