AMOUNT OF PRESSURE CAN PENETRATE SKIN
CAUSING PERSONAL INJURY OR DEATH. INSPECT
FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET
OF CARDBOARD PLACED IN THE SUSPECTED
AREA WHILE THE ENGINE IS NOT RUNNING.
START THE VEHICLE AND ALLOW THE ENGINE TO
RUN FOR A SHORT PERIOD. TURN THE ENGINE
OFF AND INSPECT THE PIECE OF CARDBOARD.
WEAR SAFETY GOGGLES AND ADEQUATE PRO-
TECTIVE CLOTHING WHEN SERVICING FUEL SYS-
TEM.

WARNING

WARNING: UNDER NO CIRCUMSTANCES SHOULD
GASOLINE BE MIXED WITH DIESEL FUEL (NOT
EVEN DURING WINTER). THE HIGH PRESSURE
PUMP IS LUBRICATED BY DIESEL FUEL. IMMEDI-
ATE FUEL SYSTEM DAMAGE MAY OCCUR CAUS-
ING

REPLACEMENT

AND

FLUSHING

THE

COMPLETE DIESEL FUEL SYSTEM. HIGH PRES-
SURE PUMP SEIZURE WILL CAUSE METAL PARTI-
CLES TO SPREAD THROUGH OUT THE FUEL

CIRCUIT. ALL CDI FUEL SYSTEM COMPONENTS
CONNECTED TO THE FUEL CIRCUIT WILL HAVE TO
BE EXCHANGED AND THE LINES FLUSHED.

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - HIGH PRESSURE
FUEL LINES

WARNING: HIGH-PRESSURE FUEL LINES DELIVER
FUEL UNDER EXTREME PRESSURE FROM THE
INJECTION

PUMP

THE

INJECTORS.

THIS

MAYBE AS HIGH AS 1600BAR (23,200PSI). USE
EXTREME CAUTION WHEN INSPECTING FOR HIGH-
PRESSURE

FUEL

LEAKS.

FUEL

UNDER

THIS

High-pressure fuel line leaks can cause starting

problems and poor engine performance.

• Turn the engine off.

• Place a piece for cardboard in the suspected area

(Fig. 1).

• Start the engine and allow to run for a short

period.

• Turn the engine off.

• Inspect the cardboard.

FUEL SYSTEM

14 - 1

If a high-pressure line connection is leaking, coun-

terhold and tighten the connection to specification
then perform this procedure again (Refer to 14 -
FUEL

SYSTEM

STANDARD

PROCEDURE).

Replace any damaged, restricted or leaking high-
pressure fuel lines with the correct replacement
line.

CAUTION: The high-pressure fuel lines cannot con-
tact each other or other components. Do not
attempt to weld high-pressure fuel lines or to repair
lines that are damaged. Only use the recommended
lines when replacement of high-pressure fuel line is
necessary.

DIAGNOSIS AND TESTING - AIR IN FUEL SYS-
TEM

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.

Inspect the fuel system from the fuel tank to the

injectors for loose connections (Refer to 14 - FUEL
SYSTEM - WARNING). Leaking fuel is an indicator
of loose connections or defective seals. Air can also
enter the fuel system between the fuel tank and the
fuel pump. Inspect the fuel tank module and fuel
lines for damage that might allow air into the sys-
tem.

With the DRBIII

t connected to the vehicle, select

Engine and the select Sensor Display. Page down to
view Fuel Pressure Set Point and Actual Fuel Pres-
sure. Start the engine and observe the Fuel Pressure
Set Point and the Actual Fuel Pressure. If the Actual
Fuel Pressure Oscillates above and below the Fuel
Pressure Set Point in a regular cycle, inspect the fuel
system for air intrusion.

If the Actual Fuel Pressure gradually drops below

the Fuel Pressure Set Point then spikes well above
the Fuel Pressure Set Point, replace the fuel pres-
sure soleniod (Refer to 14 - FUEL SYSTEM/FUEL
INJECTION/FUEL

PRESSURE

SOLENOID

REMOVAL), and recheck.

DIAGNOSIS AND TESTING - INJECTOR LEAK
QUANTITY

WARNING: REVIEW THE HIGH PRESSURE FUEL
SYSTEM WARNING BEFORE BEGINNING SERVICE
(Refer to 14 - FUEL SYSTEM - WARNING).

CRANKING TEST

NOTE: If an injector is found to be out of specifica-
tion, repeat this test procedure after the injector
replacement. Hydraulic flow will take the path of
least resistance and multiple failures may be identi-
fied.

Perform this test with the engine at operating tem-

perature, when possible. This test will assist in
determining a defective or internally leaking injec-
tor(s) is present by measuring the amount of fuel
return.

(1) Turn the ignition off.
(2) Remove the engine cover (Refer to 9 - ENGINE

- REMOVAL).

(3) Disconnect the fuel return hoses at the top of

the injectors.

(4) Pinch off the fuel return line at the banjo bolt

fitting of the fuel rail.

(5) Disconnect the fuel rail solenoid and camshaft

position sensor.

(6) Install the test vials onto the injectors and

secure with the return hose clips (Fig. 2).

Fig. 1 Typical Test for Leaks with Cardboard

1 - HIGH-PRESSURE LINE
2 - CARDBOARD
3 - FITTING

14 - 2

FUEL SYSTEM

(7) Connect a scan tool, select from Main Menu,

System Select, Engine, System Tests, Fuel Quantity
Test, Engine Cranking Test and follow the screen.

(8) After ten seconds, a maximum of 2.5 ml

(between 2 & 3 graduation lines) may be reached in
the inner vials. If the level has exceeded the 2.5 ml,
replace that affected cylinder’s injector, clear the
memory using the scan tool, empty the test vials, and
retest.

RUNNING TEST

Perform this test with the engine at operating tem-

perature. This test will assist in determining a defec-
tive or internally leaking injector(s) is present by
measuring the amount of fuel return.

(1) Turn the ignition off.
(2) Remove the engine cover (Refer to 9 - ENGINE

- REMOVAL).

(3) Disconnect the fuel return hoses at the top of

the injectors.

(4) Pinch off the fuel return line at the banjo bolt

fitting of the fuel rail.

(5) Install the test vials onto the injectors and

secure with the return hose clips (Fig. 2).

(6) Connect a scan tool, select from Main Menu,

System Select, Engine, System Tests, Fuel Quantity
Test, Engine Running Test and follow the screen.

(7) After ten seconds, a maximum of five gradua-

tion lines (40 ml) of the large test vial may be

reached. If the level has exceeded the five graduation
line, replace that affected cylinder’s injector, clear the
memory using the scan tool, empty the test vials, and
retest.

STANDARD PROCEDURE

STANDARD PROCEDURES - CLEANING FUEL
SYSTEM COMPONENTS

CAUTION: Cleanliness cannot be overemphasized
when handling or replacing diesel fuel system com-
ponents. This especially includes the fuel injectors,
high-pressure fuel lines, fuel rail, and fuel injection
pump. Very tight tolerances are used with these
parts. Dirt contamination could cause rapid part
wear and possible plugging of fuel injector nozzle
tip holes. This in turn could lead to possible engine
misfire. Always wash/clean any fuel system compo-
nent thoroughly before disassembly and then air
dry. DO NOT wire brush injector nozzles when
cleaning. Cap or cover any open part after disas-
sembly. Before assembly, examine each part for
dirt, grease or other contaminants and clean if nec-
essary. When installing new parts, lubricate them
with clean engine oil or clean diesel fuel only.

STANDARD PROCEDURES - DRAINING WATER
FROM FUEL FILTER

Connect a hose to the Water in Fuel (WIF) drain

and place it in a clearly marked and suitable con-
tainer. Open the WIF drain by turning counterclock-
wise (Fig. 3). Turn the ignition key on for 20 seconds
(Refer to low pressure fuel pump operation). Repeat
the procedure until all water is removed, close the
drain and remove the hose.

Fig. 2 Special Tool # 9545

1 - SPECIAL TOOL #9545

FUEL SYSTEM

14 - 3

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