DODGE TRUCK 1993 Service Repair Manual

14-92
FUEL
SYSTEM

• A broken injection pump timing mechanism spring
will cause the timing to be fully advanced resulting
in torque loss, a fuel knock and possible engine over­
heating.
An improperly operating KSB (cold start) solenoid
will cause white smoke during engine warm-up. The
KSB solenoid is not serviceable.
A defective or non-adjustable fuel injection pump
can cause starting problems or prevent the engine
from revving up. It can also cause:
• Engine surge at idle • Rough idle (warm engine)
• Engine miss under load
• Low power
• Excessive fuel consumption
• Poor performance
• Low power
• Black smoke from the exhaust • Blue or white fog like exhaust
• Incorrect idle or maximum speed A worn fuel injection pump plunger can effect fuel
pressure and the amount of fuel injected. This results in reduced engine power. In most cases, if the injec­
tion pump is delivering fuel from one outlet, it will deliver fuel from all outlets. If the internal plunger is defective, the fuel injection pump must be re­
placed.
Engine power is also effected by the governor set­
ting and performance. Do not attempt to adjust the governor. If the governor seals on the external adjustment screw are broken, the fuel rate may
be out of adjustment. The warranty of the injec­ tion pump and the engine may be void if the
seals have been tampered with or removed.

FUEL
INJECTORS
A leaking fuel injector can cause fuel knock, poor
performance, black smoke, poor fuel economy and
rough engine idle. If the fuel injector needle valve
does not operate properly, the engine may misfire and produce low power. A leak in the injection pump-to-injector high pres­
sure fuel line can cause many of the same symptoms as a malfunctioning injector. Inspect for a leak in the
high pressure lines before checking for a malfunc­
tioning fuel injector.

WARNING:
THE
INJECTION PUMP SUPPLIES HIGH
PRESSURE
FUEL
OF
APPROXIMATELY
59,000
KPA

(8,000
PSI) TO
EACH INDIVIDUAL INJECTOR
THROUGH THE HIGH
PRESSURE
LINES. FUEL UN­
DER
THIS AMOUNT
OF
PRESSURE
CAN
PENE­
TRATE THE SKIN AND CAUSE PERSONAL INJURY,
WEAR
SAFETY GOGGLES
AND
ADEQUATE PRO­
TECTIVE CLOTHING. AVOID CONTACT
WITH
FUEL
SPRAY
WHEN BLEEDING HIGH
PRESSURE
FUEL
LINES.
WARNING:
DO NOT
BLEED
AIR
FROM
THE
FUEL

SYSTEM
OF A
HOT ENGINE.
DO
NOT ALLOW FUEL
TO SPRAY ONTO THE EXHAUST MANIFOLD WHEN
BLEEDING
AIR
FROM THE FUEL SYSTEM.

To determine which fuel injector is malfunctioning,
run the engine and loosen the high pressure fuel line nut at the injector. Listen for a change in engine
speed (Fig. 14). Tighten the line nut. If engine speed

drops,
the injector was operating normally. If engine
speed remains the same, the injector is malfunction­
ing. Test all injectors in the same manner one at a

time.

Fig. 14
Inspecting
Injector Operation
Once an injector has been found to be malfunction­
ing, remove it from the engine and replace it. Refer
to Diesel Engine Service Procedures for injector re­ moval and installation.

FUEL
SUPPLY
RESTRICTIONS

CAUTION:
Do not
operate
the
engine
if the
fuel
sup­ ply
line
has
a
restriction
of
more
than
12.7
kPa
(3.75
in
Hg).
Refer
to
Lift
Pump
Test.

Fuel supply line restrictions can cause starting
problems and prevent the engine from revving up.
The starting problems include; engine miss under load, low power and blue or white fog like exhaust.
Test all fuel supply lines for restrictions or blockage.
Flush or replace as necessary. Bleed the fuel system
of air once a fuel supply line has been replaced.

FUEL/WATER
SEPARATOR
FILTER
A blocked or clogged fuel/water separator filter can
cause starting problems and prevent the engine from
revving up. It can also cause engine miss under load,
low power and blue or white fog like exhaust. The maximum allowable fuel pressure drop across
the fuel/water filter separator is 21 kPa (3 psi).

•

FUEL SYSTEM
14-93 There is a drain at the bottom of the separator fil­
ter (Fig. 13). Place a drain pan under the drain tube. With the engine not running, hold the drain open
until all water and contaminants have been removed and clean fuel exits the drain. Dispose of mixture in
drain pan according to applicable regulations.
If excess water gathers in separator/filter in a short

time,
the fuel tank must be removed, drained and cleaned.

HIGH
PRESSURE FUEL LINE RESTRICTIONS
High pressure fuel line leaks can cause starting
problems, poor engine performance and engine miss under load. Restricted high pressure lines can cause starting problems, poor engine performance, engine
miss under load and black smoke from exhaust.

WARNING:
USE
EXTREME
CAUTION
WHEN
IN­
SPECTING
FOR HIGH
PRESSURE
FUEL
LEAKS.
IN­

SPECT
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.

Start the engine. Move the cardboard over the high
pressure fuel lines and check for fuel spray onto the cardboard. If a high pressure line connection is leak­
ing, bleed the system and tighten the connection. Re­
fer to the 5.9L Diesel Service Procedures section for air bleeding procedures. Replace damaged, restricted
or leaking high pressure fuel lines with the correct replacement line.

CAUTION:
The
high pressure
fuel
lines must
be

clamped securely
in
place
in the
holders.
The
lines cannot contact each other
or
other components.
Do
not
attempt
to
weld high pressure
fuel
lines
or to

repair lines
that
are
damaged. Only
use the
recom­
mended lines when replacement
of
high pressure

fuel
line
is
necessary.

KSB
SOLENOID
The KSB solenoid will click when it is energized
and de-energized. If the solenoid does not click when 12 volts is sup­
plied to it, replace the solenoid.

MECHANICAL
LIFT
PUMP
An improperly operating lift pump can cause low
engine power. Inspect the fuel supply line to the
pump for restrictions, kinks or leaks. Fuel leaking
from the weep hole (Fig. 15) in the pump casing in­
dicates a leaking pump diaphragm. The lift pump is not repairable and must be replaced as an assembly.
CAUTION:
Do not
operate
the
fuel
system
with
a

suction restriction
of
more than
95 MM Hg (3.75
inch Hg). Refer
to
Lift
Pump Test.
Fig.
15
Lift
Pump
Low lift pump output can be caused by a worn ec­
centric on the engine camshaft. A properly operating lift pump will pump a minimum volume of 0.75 liter (0.70 U.S. quart) of fuel in 30 seconds at engine
cranking speed.
The maximum allowable pressure drop across the
fuel filter is 21 Kpa (3 psi). As the filter removes contaminants in the fuel, the pressure drop across
the fuel separator filter will increase. Frequent re­
placement of the separator filter can indicate a worn lift pump. Refer to the Maintenance Schedule at the
front of this manual for recommended replacement intervals.

LIFT
PUMP
TEST
(1) Disconnect fuel inlet tube at the lift pump. (2) Install T-fitting between disconnected fitting
and lift pump inlet. Connect vacuum gauge to T-fit­
ting.

WARNING:
USE
EXTREME
CAUTION
WHEN
EN­
GINE
IS
OPERATING.
DO NOT
STAND
IN
DIRECT

LINE
WITH FAN.
DO NOT PUT
HANDS
NEAR
PUL­

LEYS,
BELTS
OR FAN. DO NOT
WEAR
LOOSE

CLOTHING.

The vacuum gauge will not indicate a vacuum un­
til the lift pump begins to operate at full capacity.
(3) Operate engine at approximately 1500 rpm for
30 seconds. Vacuum should not exceed 12.7 kPa (3.75
in. Hg).
(4) If vacuum exceeds 12.7 kPa (3.75 in. Hg) check
fuel tube for restriction. A partially clogged in-tank fuel filter can also cause excess vacuum.

14
- 94
FUEL
SYSTEM

•
THROTTLE POSITION
SENSOR
TEST

CAUTION;
Before checking
the
TPS,
the
throttle
linkage must
be
checked
for
correct
adjustment.
The
throttle
lever must
contact
the low idle
speed screw.
The
throttle
lever must reach breakover when
the
throttle
is
wide
open. Refer
to the
Accelerator Pedal and
Throttle
Cable section
of
Group
14,
Fuel Systems.

The throttle position sensor (TPS) can be tested
with the DRB II or a digital voltmeter (Fig. 16). The center terminal of the TPS is the output terminal.

J9114-244

Fig.
16
Throttle
Position
Sensor
(TPS) Testing
Turn the ignition key to the On position. Check
TPS output voltage at the center terminal wire of the connector. Measure the voltage at idle (throttle lever contacting low idle speed screw) and at wide open
throttle
(WOT).
At idle TPS output voltage should be approximately 1 volt. At wide open throttle, the TPS
output voltage must be 2.25 to 2.75 volts higher than
the reading at idle. The output voltage should in­
crease gradually as the throttle lever is slowly
opened from idle to WOT. If the TPS is not within
the proper range, adjust the sensor. Refer to the Die­ sel Fuel Injection—Service Procedures section of this
group.

ON-BOARD
DIAGNOSTICS
(OBD) The powertrain control module (PCM) has been
programmed to monitor many different circuits. If a
problem is sensed in a monitored circuit often enough to indicate an actual problem, a diagnostic
trouble code (DTC) is stored. The DTC will be stored in the PCM memory for eventual display to the ser­
vice technician. If the problem is repaired or ceases
to exist, the PCM cancels the DTC after 51 engine
starts.

Certain criteria must be met for a diagnostic trou­
ble code (DTC) to be entered into PCM memory. The criteria may be a specific range of engine rpm, en­gine temperature and/or input voltage to the PCM. It is possible that a DTC for a monitored circuit
may not be entered into memory even though a mal­
function has occurred. This may happen because one of the DTC criteria for the circuit has not been met.
ACCESSING DIAGNOSTIC TROUBLE CODES A stored diagnostic trouble code (DTC) can be dis­
played by cycling the ignition key On-Off-On-Off-On
within three seconds and observing the malfunction indicator lamp. This lamp was formerly referred to
as the check engine lamp. The lamp is located on the
instrument panel.
They can also be displayed through the use of the
Diagnostic Readout Box II (DRB II scan tool). The
DRB II connects to the data link connector in the en­
gine compartment. For operation of the DRB II, refer
to the appropriate Powertrain Diagnostic Procedures service manual.

EXAMPLES

• If the lamp flashes 4 times, pauses and flashes 1
more time, a diagnostic trouble code (DTC) number
41 is indicated.
• If the lamp flashes 4 times, pauses and flashes 6
more times, a diagnostic trouble code (DTC) number 46 is indicated. Refet* to the Diagnostic Trouble Code (DTC) charts
for DTC identification. If the problem is repaired or ceases to exist, the
powertrain control module (PCM) cancels the DTC after 51 engine starts.
Diagnostic trouble codes indicate the results of a
failure, but never identify the failed component di­
rectly.
The circuits of the data link connector are shown
in (Fig. 17).
J9214-20
D-1
1
GROUND

D-2
N/C
D-3
SCI
TRANS

D-4
SCI
RECEIVE
D-5 IGNITION

D-6
NOT USED
Fig.
17
Data
Link
Connector
Schematic

ERASING TROUBLE CODES The DRB II scan tool must be used to erase a di­
agnostic trouble code (DTC). Refer to the appropriate
Powertrain Diagnostic Procedures service manual for
operation of the DRB II scan tool.

•

FUEL SYSTEM
14 - 95
DRB
II
SCAN
TOOL

For operation
of the DRB II
scan tool, refer
to the

appropriate Powertrain Diagnostic Procedures ser­
vice manual.

DIAGNOSTIC TROUBLE CODE (DTC)
On
the
following pages,
a
list
of
diagnostic trouble
codes
is
provided
for the
diesel engine.
A DTC
indi­ cates that
the
powertrain control module
(PCM) has

recognized
an
abnormal signal
in a
circuit
or the
sys­
tem.
A DTC may
indicate
the
result
of a
failure,
but
never identify
the
failed component directly.

SYSTEM SCHEMATICS—5.9L DIESEL ENGINE
Refer
to the
following system schematic
for the

5.9L diesel engine.

5.9L DIESEL DIAGNOSTIC TROUBLE CODES (DTC)
Fault
Code
DRBII
Display
Description
of Fault
Condition

11 No Reference Signal During Cranking
15 No Vehicle Speed Signal
22 Coolant Sensor Voltage Too Low or
Coolant Sensor Voltage
Too High
23 Charge Air Temperature Sensor Voltage High or
Charge Air Temperature Sensor Voltage Low

24*
TPS Voltage High or
TPS Voltage Low
33 A/C Clutch Relay Circuit
34 Speed Control Solenoid Circuits
41 Generator Field Not Switching Properly
42 Auto Shutdown Relay Control Circuit
or
No ASD Relay Voltage
Sense at PCM No reference signal from Engine Speed Sensor.
No speed sensor signal detected during road load conditions.
Coolant temperature sensor input below the minimum acceptable voltage.
Coolant temperature sensor input above the maximum acceptable voltage.
Charge Air Temperature Sensor input above/below acceptable minimum.
Throttle position sensor (TPS) input above the maximum acceptable voltage.
Throttle position sensor (TPS) input below the minimum acceptable voltage.
An open or shorted condition detected in the A/C clutch relay circuit.
An open or shorted condition detected in the speed control vacuum or vent solenoid circuits.
Generator field not switching properly.
An open or short condition detected in the auto shutdown relay circuit. No ASD voltage sensed at PCM.
*Automatic Transmission Only
J9314-182

FUEL
SYSTEM
14 - 97
5„9L DIESEL DIAGNOSTIC TROUBLE CODES {DTC}-CONTINUED
Fault
Code
DRBII Display
Description
of Fault Condition

45*
Overdrive Solenoid
46 Charging System Voltage Too High
47 Charging System Voltage Too Low
53 Internal PCM Failure
62 PCM Failure SRI Miles Not Stored
63 PCM Failure EEprom Write Denied An open or shorted condition detected in overdrive solenoid circuit.
Charging system voltage too high.
Charging system voltage too low. Internal failure in the PCM.
PCM failure - SRI miles not stored.
PCM failure - EEprom write denied.
*Automatic Transmission Only J9314-183

OVERDRIVE/OVER-RIDE

SWITCH

(AUTO
ONLY) CO
oo
c/3 -<
LSTARJERJ^
_ j

J9314-184

5.91.
DIESEL SYSTEM SCHEMATIC •

CAV

WIRE

COLOR DESCRIPTION
CAV
WIRE

COLOR DESCRIPTION

1 WT/BK
WATER-IN-FUEL SENSOR 37 OVERDRIVE LAMP SIGNAL
2 TN/BK
COOLANT SENSOR (AUTOMATIC TRANSMISSION ONLY) 38
3 RD BATTERY
39
4
BK/LB*

SENSOR RETURN 40
5 BK/WT
SIGNAL GROUND 41
6 VT/WT*
5 VOLT SUPPLY 42
7 TN/YL 8 VOLT INPUT 43 GR/LB TACHOMETER
8 44
9 DB
IGNITION SENSE 45 LG DATA LINK RECIEVE
10 RD/WT*
OVERDRIVE OVERRIDE 46
11 BK/TN POWER GROUND
47 WT/OR* VEHICLE SENSOR
12 BK/TN
POWER GROUND 48 BR/RD* SPEED CONTROL COAST/SET SWITCH
13 49 YL/RD* SPEED CONTROL ON/OFF SWITCH
14 50 WT/LG* SPEED CONTROL RESUME/ACCEL SWITCH
15 OR/BK* HEATER
#2
RELAY 51 DB/YL ASD RELAY
16 YL/BK HEATER #1 RELAY 52
17 53 LG/RD* SPEED CONTROL VENT SOLENOID
18 54 BK/PK* WATER-IN-FUEL LAMP
19 55 OR/LG* OVERDRIVE SOLENOID
20 DG GENERATOR FIELD 56 DG/WT WAIT-TO-START LAMP
21 BK/RD
CHARGE (INTAKE) AIR TEMPERATURE SENSOR 57 DG/OR ASD SENSE
22
OR/DB*

THROTTLE POSITION SENSOR 58
23 59
24 GY/BK
REFERENCE PICKUP 60
25 PK
DATA LINK TRANSMIT WIRE COLOR CODES LB
LIGHT BLUE VT VIOLET
26 BK BLACK LG LIGHT GREEN WT
WHITE
27 BR
A/C CLUTCH REQUEST BR BROWN OR ORANGE
YL YELLOW
28 LG/RD THERMO SWITCH DB DARK BLUE PK PINK *
WITH TRACER
29 WT/PK* BRAKE SWITCH DG DARK GREEN
RD RED
30 BR/YL*
PARK/NEUTRAL SWITCH GY GRAY TN TAN
31 ruin
32 BK/PK*
MALFUNCTION INDICATOR LAMP
n

33 TN/RD*
SPEED CONTROL VACUUM SOLENOID CONNECTOR

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21
22
23
24
25
26
27
28
29
30
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12 13
14 15
16 17 18
19 20
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34 DB/OR
WIDE OPEN THROTTLE (A/C) TERMINAL
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J9314-185

PCM
CONNECTOR CAVITY DESCRIPTION

14-100
FUEL
SYSTEM

•
DIESEL
FUEL
INJECTION
SYSTEM DIAGNOSIS

SYMPTOM CAUSE
ACTION

Starting problem Improper
fuel
Drain
fuel
tank,
flush
system,
fill
with
proper

fuel.
Change
filter

Empty
fuel
tank
or
fuel
tank
vent
blocked
Fill
tank, bleed system, check
tank
vent

Air in
fuel
system Bleed
fuel
system
Voltage not supplied to
fuel
solenoid or

fuel
solenoid
inoperative
Correct voltage supply problem or
replace solenoid

Clogged
fuel
filter
Replace
fuel
filter

Restricted or blocked
fuel
supply lines Remove restriction or replace lines
Leaking
injection
lines, damaged lines or
loose
connections Replace damaged lines or tighten
connections as necessary. Bleed
fuel
system
Wax buildup in
fuel
filter
(cold
weather

only) Replace
fuel
filter,
use recommended
diesel
fuel

Incorrect
injection
pump to engine timing Adjust
injection
pump timing
Malfunctioning air heating system Repair air heating system

Injection
sequence does not correspond

with
firing
order Install
fuel
injection
lines in correct order
Malfunctioning
KSB
valve Replace
injection
pump
Low or uneven engine compression Repair as necessary
Restricted or blocked
fuel
injection
lines Remove restriction or replace lines

Fuel
injection
pump malfunction or not adjustable Replace
fuel
injection
pump

Engine
Surge at
idle
Empty
fuel
tank
or
fuel
tank
vent
blocked
Fill
tank, bleed system, check
tank
vent

Air in
fuel
system Bleed
fuel
system
Low
idle
speed Adjust
idle
speed
J9H4-22

•

FUEL
SYSTEM
14 - 101
DIESEL FUEL
INJECTION
SYSTEM DIAGNOSIS-CONTINUED

SYMPTOM
CAUSE
ACTION

Engine
surges
at
idle
Fuel
injection
pump malfunction or
not adjustable Replace
fuel
injection
pump

Rough
idle
when engine Is warm Improper
fuel

Air in
fuel
system Drain
fuel
tank, flush system,
fill
with

proper
fuel
Bleed
fuel
system
Low
idle
speed Adjust
idle
speed

Injection
pump
rear
support bracket loose Repair as necessary
Restricted or damaged
injector
nozzle
Repair or replace as necessary

Injection
sequence does not correspond

with
firing
order Install
injection
lines in correct order
Low or uneven engine compression Repair as necessary

Fuel
injection
pump malfunctioning
or not adjustable Replace
fuel
injection
pump

Engine
mines under lead Improper
fuel
Drain
fuel
tank, flush system,
fill
with

proper
fuel

Empty
fuel
tank
or
fuel
tank
vent
blocked
Fill
tank, bleed system, check
tank
vent

Air in
fuel
system Bleed
fuel
system

Clogged
fuel
filter
Replace
fuel
filter

Restricted or blocked
fuel
injection
lines Remove restrictions or replace lines
Restricted or blocked
fuel
supply lines Remove restrictions or replace lines
Leaking
injection
lines, damaged lines or

loose
connection Replace damaged lines or
tighten

connections as necessary. Bleed
fuel
system. 1
J9114-23