Performing Diesel Engine Tuneup

Information Sheet 2.4.1: Identify parts and function of injection pump
Learning outcomes:
2 Inspect Injection Timing
Learning Activity:
2.4 Identifying parts function of injection pump

Diesel Fuel Injection Pumps

Automotive diesel engines use two types of fuel injection pumps. One is an inline cam-
operated pump. It has a plunger for each engine cylinder. The other is a rotary,
distributor-type pump. One or two plungers supply the fuel for all injection nozzles.

Inline-Plunger Injection Pump

Figure 2.0 shows an inline-plunger pump on a six-cylinder diesel engine. The pump has
a barrel-and-plunger assembly for each cylinder.

Injection nozzles

High pressure
lines

In-line injection pump
Fig. 2.0 shows the location of in-line injection pump

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
ALT723301 Aug 15, 2003
Sept. 20, 2010 1

Information Sheet 2.4.1: Identify parts and function of injection pump

An injection line or tube connects each barrel-and-plunger assembly to an injection
nozzle. The construction of a barrel-and-plunger assembly is shown in Figure 2.1. Low-
pressure fuel from the fuel supply pump flows through the inlet port (Figure 2.2) into the
space above the plunger. The plunger has a roller that rides on a cam on the camshaft.
This is like the roller tappets used in some engine valve trains. When the cam lobe
comes up under the plunger, the lobe raises the plunger. This applies high pressure on
the fuel trapped above the plunger. The fuel is forced through the tube to the injection
nozzle in the cylinder where the piston is reaching TDC on the compression stroke. The
fuel sprays out and ignites from the heat of the compression.

Fig. 2.1 Construction of an in-line plunger injection pump

An injection line or tube connects each barrel-and-plunger assembly to an injection
nozzle. The construction of a barrel-and-plunger assembly is shown in Figure 2.2. Low-
pressure fuel from the fuel supply pump flows through the inlet port (Figure 2.3) into the
space above the plunger. The plunger has a roller that rides on a cam on the camshaft.
This is like the roller tappets used in some engine valve trains. When the cam lobe
comes up under the plunger, the lobe raises the plunger. This applies high pressure on
the fuel trapped above the plunger. The fuel is forced through the tube to the injection
nozzle in the cylinder where the piston is reaching TDC on the compression stroke. The
fuel sprays out and ignites from the heat of the compression.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Sept. 20, 2010 2

Information Sheet 2.4.1: Identify parts and function of injection pump

Fig. 2.3 Movement of the toothed control rod turns the inline-pump plungers to vary the
amount of fuel injected

Turning the plunger for more fuel rotates the helix so a wider section faces the
inlet port. This closes the port for a longer time, increasing the effective stroke of the
plunger. Fuel delivery begins when the top edge of the plunger closes off the inlet port.
Fuel delivery stops when the helix opens the inlet port. The fuel-injection pump has a
speed-advance mechanism. It advances the time of injection as engine speed
increases. This gives the fuel the necessary time to ignite burn and produce high
pressure. Without injection advance, weak power strokes result at higher engine
speeds.

Rotary-Distributor Injection Pump

Figure 2.4 shows a V-8 engine fuel system using a rotary distributor injection
pump. This pump has a rotor that sends fuel to the injection nozzles in the engine
cylinder as it rotates. The pump is driven by a pair of bevel gears at half crankshaft
speed. Figure 2.4 shows the distributor pump removed from the engine. It has a rotor
with a pair of cam rollers and plungers. These rollers roll on the inner surface of an
internal cam. They move in and out as they roll over the cam lobes.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Sept. 20, 2010 3

Information Sheet 2.4.1: Identify parts and function of injection pump

When it moves out, it causes the plungers to move out. This increases the size
of the internal chamber. Then the rollers meet the cam lobes and push the plungers in.
This pressurizes the fuel, forcing it out through an opening in the rotor.

The opening indexes with stationary opening in the outer shell of the pump.
There are the same numbers of these openings as there are cylinders in the engine. As
injection pipe connects each opening to an injection nozzle in a cylinder. As the motor
turns, its opening indexes with the stationary openings. This sends high-pressure fuel to
the injection nozzles in the firing order.

Fig. 2.4 shows the construction of rotary injection pump

Distributor-Pump Controls

The distributor has two controls. One controls timing and the other controls the amount
of fuel injected. The timing device connects to the internal cam ring. This is the cam on
which the rollers roll as shown below figure 2.5. As engine speed increases, the cam
ring moves ahead. This causes the two plungers to move out and in earlier, advancing
the start of injection. At the same time, the internal governor regulates the amount of
fuel delivered to the cylinders.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Sept. 20, 2010 4

Information Sheet 2.4.1: Identify parts and function of injection pump

Fig. 2.5 Two views of the distributor-pump automatic advance system that
provides automatic advance of injection timing. Hydraulic pressure, which
increases with speed and moves the cam ahead.

Mechanical Governors for fuel-Injection Pumps

Moving the accelerator pedal changes the setting of the governor. It then
automatically controls the amount of fuel injected see figure 2.6. Without a governor, a
diesel engine can stall at low speeds or run so fast it will self-destruct. Automotive diesel
engines use a mechanical governor (centrifugal), pneumatic, or electronically-controlled
governor. These are all variable-speed governors. They control an engine that runs at
varying speeds.

Note: Engines that run at constant speed, such as diesel engine that drives an electric
generator, use constant-speed governors.

A mechanical governor has flyweights that spin with the injection-pump camshaft.
The faster they spin, the further out they move. This acts on the plungers and adjusts
the fuel delivery.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 2.4.1: Identify parts and function of injection pump

Governor side

Flyweight

Fig. 2.6 shows the location of governor on inline injection pump

A venture section in the intake manifold connects by a hose to a vacuum
chamber in the governor. As the driver changes accelerator-pedal position, the throttle-
valve position also changes. This change the amount of vacuum applied to the
diaphragm in the vacuum chamber. The diaphragm moves, repositioning the control rod
in the injection pump. This rotates the plungers to vary the amount of fuel delivered.

Intake manifold

Throttle valve

Vacuum hose

Pneumatic governor

Figure 2.7 Shows an engine with a pneumatic governor. It has a throttle valve in the intake
manifold to provide a vacuum signal to the governor. This valve does not control airflow in the
engine.

Some diesel engines are turbocharged (Figure 2.8). In these engines, the
governor is connected by a tube to the intake manifold. This allows the governor to
match fuel delivery with the pressure (the amount of air) in the intake manifold. Air-fuel
ratios in a diesel engine range from about 100:1 at idle to about 20:1 under full load.
The governor keeps the air-fuel ratio within these limits. An air-fuel ratio richer than 20:1
produces unacceptable smoke in the exhaust

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 2.4.1: Identify parts and function of injection pump

Fig. 2.8 Turbo charger

Mechanical and pneumatic governors are relatively slow to act. This may cause
the engine to receive the wrong amount of fuel. Then the engine may hesitate or the air-
fuel ratio may be too rich, causing smoke in the exhaust gas.
Electronic controls act almost instantly to changed conditions. This maintains the proper
air-fuel ratio as operating conditions change.

Diesel Electronic-Control System

A diesel engine may have an electronic control system with an electronic control
module (ECM). The ECM may only control the emissions systems, or it may increase
the fuel-metering accuracy of the governor. On some engines, the electronic control
system completely replaces the mechanical governor. The ECM monitors sensors for
engine speed, vehicle speed, throttle position, torque-converter clutch, and other
conditions. These inputs are evaluated. Then the ECM calculates the correct amount of
fuel to be injected. See below figures 2.9 – 2.12 are some of the components of diesel
electronic-control system.

Fig. 2.9 VP 44 Electronic injection pump Fig. 2.10 Mother board of pump
control unit

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 2.4.1: Identify parts and function of injection pump

Fig. 2.12 an example of
ECM

Fig. 2.11 Show the Common Rail Direct
Injection (CRDI)

Injection Nozzle

A spring holds the needle valve or nozzle valve closed until the high injection
pressure is applied through the injection pipe see figure 2.13. This forces the valve off
its seat so fuel sprays out into the cylinder. The instant the pressure drops, the spring
reseats the valve and fuel injection stops.

Fig.2.13 Injection nozzles

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 2.4.1: Identify parts and function of injection pump

Fig. 2.14 Parts of nozzle injector

Direct and Indirect Injection

Figure 2.15 is an example of direct injection diesel engine. In “History of Diesel
Engine” shows a diesel engine using direct injection. The fuel is injected directly into the
combustion chamber.

Diesel engine for trucks and heavy equipment use direct injection. It causes
harder starting and rougher and noisier operation. Direct injection is not normally used
in passenger-car engines.

Injection Nozzle Valve
Glow plug Fig. 2.15 Direct diesel injection
Piston

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 2.4.1: Identify parts and function of injection pump

Figure 2.16 shows indirect injection. The fuel for each cylinder is injected into a
precombustion chamber. A glow plug has a small electric heating element. It heats the
air in the precombustion chamber during cold weather to assure easy starting. Instead
of glow plugs, some diesel engines have an electronic intake manifold heater to warm
the intake air.

Glow plug Injection Nozzle
Intake Manifold Glow plug

Piston

Fig, 2.16 an example of diesel engine indirect injection

The fuel ignites in the precombustion chamber and streams out into the main
combustion chamber. There the burning fuel mixes with the combustion-chamber air
and combustion is completed. A diesel engine always has excess air so combustion is
relatively complete.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Worksheet 2.4.2 : Identify parts and functions of injection pump

Learning outcomes:

2. Inspect injection timing

Learning Activity:

2.4 Identifying parts and functions of injection pump

Multiple Choice:

Instruction: Select the correct answer and write the letter on

your answer sheet provided for.

1. A device mounted on the injection pump which is use to lift fuel from the tank to the

injection system.
a. filter.
b. injector.
c. feed pump.
d. injection pump.

2. The two holes or ports of the barrel of the injection pump are called
a. control rod and helix.
b. inlet port and spill port.
c. inlet and outlet valve.
d. plunger and injector.

3. A device use to deliver an exact metered amount of fuel to the injector nozzle?
a. feed pump.
b. injection nozzle.
c. injection pump.
d. lift pump.

4. A device use to separate water from fuel is?
a. gallery.
b sedimenter.
c. plunger.
d. injection pump.

5. Part of the injection system use to remove abrasive particles and
water is called?
a. camshaft.
b. feed pump.
c. filt
d. plunger.

6. A camshaft, cam follower and spring move the plunger in what motion?
a. . rotary motion.
b. slow motion.
c reciprocating motion.
d. rotary and reciprocating motion.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Worksheet 2.4.2 : Identify parts and functions of injection pump

7. Which of the following is part of the rotary injection pump?
a. crankshaft.
b. injector nozzle.
c. in-line cam.
d. rotor blade.

8. The top edge of annular groove is a cut in a helix is called?
a. control edge.
b. lower groove.
c. upper groove.
d. valve holder.

9. What are the two elements that fits inside the injection pump assembly?
a. barrel and plunger
b. in-line and rotary
c. camshaft and cam follower
d. rocker arm and shaft

10. Automotive diesel engine used two types of injection pump .One is an in-line cam
operated, while the other one is called?
a. mechanical governor.
b. in-line injection pump
c. pneumatic governor.
d. rotary injection pump.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Nov. 28, 2003 Sep. 20, 2010 2

Worksheet 2.4.2 : Identify parts and functions of injection pump

Answers Key:

1. C
2. B
3. C
4. B
5. C
6 .C
7. D
8. A
9. A
10. D

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Nov. 28, 2003 Sep. 20, 2010 3

Information Sheet 2.5.1: Identify the parts, types and functions of fuel injector

Learning outcomes:
2. Set and install injection pump to engine.
Learning Activity:
2.5 Identifying the parts, types and functions of fuel injector.

DIESEL INJECTOR NOZZLES

Diesel injector nozzles are spring-loaded valves that spray fuel directly into the
engine pre combustion chambers. See Fig. 3.1.The injector nozzles are threaded into
the cylinder head. One injector is provided for each engine cylinder. The inner tip of the
injector nozzle is exposed to the heat of combustion, like a spark plug in a gasoline
engine.

Fig. 3.1. Diesel injector screws into the cylinder head. Heat
shield fits between injector body and head. Fuel is injected
into pre combustion chamber.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
ALT723301 Aug 15, 2003
Sept. 20, 2010 1

Information Sheet 2.5.1: Identify the parts, types and functions of fuel injector

Diesel injector parts

The basic parts of a diesel injector are pictured in Fig. 3.2 .Look at these
illustrations as the parts are explained.

A diesel injector heat shield helps protect the injector from heat. It also helps
make a good seal between the injector and the cylinder head.

The injector body is the main section of the injector that holds the other parts.
The body threads into the heat shield. The heat shield threads into the cylinder head.
Fuel passages are provided in the injector body. A needle seat is formed by the lower
opening in the injector body.

Fig. 3.2 Basic diesel injector construction. Note parts names, shapes, and location.

The diesel injector needle valve opens and closes the nozzle. It is a precisely
machined rod with a specially shaped tip. The tip of the needle seals against the
injector body when closed.

The injector spring holds the injector needle in the normally closed position. It fits
around the needle and against the injector body. Spring tension helps control injector
opening pressure.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Sept. 20, 2010 2

Information Sheet 2.5.1: Identify the parts, types and functions of fuel injector

An injector pressure chamber is formed around the tip of the injector needle and
inner cavity in the injector body. Injection pump pressure forces fuel into this chamber to
push the needle valve open.

Diesel injector nozzle operation
When the injection pump produces high pressure, fuel flows through the injection

line and into the inlet of the injector nozzle. Look at Fig. 3.3. Fuel then flows down
through the fuel passage in the injector body and into the pressure chamber.

High pressure from injection pump enters top of injector
valve. Fuel flows through the body passage to pressure
chamber. With enough injection pressure , needle valve is
pushed up and fuel sprays into precombustion chamber.

Figure 3.3 shows the cut away of injector to trace the fuel flow

The high pressure in the chamber forces the needle upward, compressing the
injector spring. This allows diesel fuel to spray out forming a CONESHAPED spray
pattern. Some fuel leaks past the injector needle and returns to the fuel tank through the
return lines.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 2.5.1: Identify the parts, types and functions of fuel injector

Diesel injector nozzle types
Several types of injector nozzles are used in diesel engines. The most common

of these are the:
1. Inward opening injector nozzle
2. Outward opening injector nozzle
3. Pintle injector nozzle
4. Hole injector nozzle

Most automotive diesel used an inward opening, pintle type injector nozzle.
Some spray pattern as shown figure 3.4.

Figure 3.4 shows different types of injector

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Sept. 20, 2010 4

Worksheet 2.5.2 Identify the parts and functions of diesel fuel injector
Learning outcomes:
2. Set and install injection pump to engine
Learning Activity:
2.5 Identifying parts and functions of diesel fuel injector

Multiple Choice:

Instruction: Select the correct answer and write the letter on the sheet
provided for.

1. The spring loaded part of injector nozzle that produces high pressure of fuel to
the injection pipe is called
a. nozzle
b. shim
c. needle valve
d. pintle nozzle

2. The main of injection nozzle that hold the other parts is called
a. injector body
b. injector spring
c. injection pump
d. injection return line

3. The spring loaded valves that spray fuel directly into the engine precombustion
Chambers is called
a. direct injector
b. indirect injection
c. injection body
d. injection nozzle

4. The part of the injector nozzle that closes and opens the fuel is called
a. needle spring
b. needle valve
c. pressure chamber
d. return line

5. The part that holds the injector needle in the normal closed position is called
a. fuel passage
b. injection spring
c. injector shield
d. needle valve

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Nov. 28, 2003 Spt. 20, 2010 1

Worksheet 2.5.2 Identify the parts and functions of diesel fuel injector

6. The part that formed around the tip of injector needle and inner cavity in the
injector body is called
a. Injector body
b. Injector pressure
c. Injector spring
d. Heat shield

7. Which one common type of injection nozzle used in diesel engine ?
a. hole type
b. pint aux type
c. pintle type
d. spray hole type

8. The injector nozzle are threaded into the
a. cylinder block
b. cylinder bore
c. cylinder head
d. cylinder liner

9. The inner tip of the injector nozzle is exposed to the heat of
a. combustion
b. compression
c. exhaust
d. fire

10. A needle seat is formed by the lower opening in the_____?
a. injector body
b. injector spring
c. heat shield
d. needle valve

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Worksheet 2.5.2 Identify the parts and functions of diesel fuel injector

ANSWERS KEY

1. A
2. A
3. D
4. B
5. B
6. B
7. C
8. C
9. A
10. A

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Nov. 28, 2003 Spt. 20, 2010 3

Job Sheet 2.6.1: Perform checking injection nozzle
Learning outcomes:
2 Inspect injection timing
Learning Activity:
2.6 Perform checking injection nozzle

Note: Never remove an injection nozzle from the engine except for service or
replacement.

The following indicate injection-nozzle trouble:

• One or more cylinder knocking.
• Loss of power.
• Smoky black exhaust.
• Engine overheating.
• Excessive fuel consumption.

1. One way to check injection nozzles is to run the engine at fast idle.

2. Loosen the connector at each nozzle in turn, one at a time.

3. Wrap a cloth around the connection before you loosen it to keep fuel from spurting
out. If loosening the connector causes engine speed to drop, the nozzle is probably
working normally. If the engine speed remains the same, the nozzle is not working
properly. Clogged holes are preventing fuel delivery or causing an improper spray
pattern (Table 2.0). Turn the engine off.

Some manufacturers recommend a spray test of the detached injection nozzle. This
requires a nozzle tester, which is a special hydraulic pump and pressure gauge.

4. Attach the nozzle and apply pressure. The fuel should spray in an acceptable
pattern (Figure 2.0) when the specified pressure is reached.

5. Releasing the pressure should stop the spray abruptly without any drip from the
nozzle.

Caution: Direct the spray from the nozzle into a suitable container. Do not allow the
spray to hit your skin. The pressure is high enough to force fuel oil through the skin. You
can be seriously injured because the oil could cause an infection.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Nov. 28, 2003 Sept. 20, 2010 1

Job Sheet 2.6.1: Perform checking injection nozzle

If the engine misses at all speeds and
produces a puff of exhaust smoke each
time it misfires, an injection nozzle is
probably sticking open. The nozzle can be
disassembled and cleaned. Some
manufacturers recommend replacing a
faulty nozzle.

Caution: If you disassemble a nozzle, do
not damage the tip or enlarge the holes.
This can cause leakage and other
troubles.

Figure 2.0. Injection-nozzle spray patterns.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Nov. 28, 2003 Sept. 20, 2010 2

Job Sheet 2.6.1: Perform checking injection nozzle

Table 2.0: DIESEL FUEL-INJECTION SYSTEM TROUBLE-DIAGNOSIS CHART

Complaint Possible Cause Check or Correction

1. Engine cranks a. incorrect or dirty fuel Flush system—use correct fuel
normally but will not b. No fuel to nozzles or injection Check for fuel to nozzles
start
pump Check return line, clean
2. Engine starts but c. Plugged fuel-return line Retime
stalls on idle d. Pump timing off
e. Inoperative glow plugs, Fill tank
3. Rough idle, no Flush system—use correct fuel
abnormal noise or incorrect starting procedure, Check for fuel to nozzles and to
smoke or internal engine problems pump
a. Fuel low in tank
4. Rough idle with b. Incorrect fuel or dirty fuel Check return line, clean
abnormal noise and c. Limited fuel to nozzles or Reset idle
smoke injection pump Retime
d. Restricted fuel-return line Install new pump
5. Idle okay but e. Idle incorrectly set
misfires as throttle f. Pump timing off Adjust
opens g. Injection-pump trouble Fix leaks
h. Internal engine problem Clear
a. Low idle incorrect Check, repair or replace
b. Injection line leaks Check, replace if necessary
c. Restricted fuel-return line Selectively replace nozzles until
d. Nozzle trouble condition clears up
e. Fuel-supply-pump problem Flush system—use correct fuel
f. Uneven fuel distribution to Retime
nozzles Check cylinders in sequence to
g. Incorrect or dirty fuel. find defective nozzle
a. Injection-pump timing off Replace filter
b. Nozzle trouble Retime
Flush system—use correct fuel
a. Plugged fuel filter
b. Injection-pump timing off
c. Incorrect or dirty fuel

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Job Sheet 2.6.1: Perform checking injection nozzle

6. Loss of power a. Incorrect or dirty fuel Flush system—use correct fuel
b. Restricted fuel-return line Clear
7. Noise—“rap” from c. Plugged fuel-tank vent Clean
one or more d. Restricted fuel supply Check fuel lines, fuel-supply
cylinders pump, injection pump
e. Plugged fuel filter Replace filter
8. Combustion noise f. Plugged nozzles Selectively test nozzles, replace
with excessive as necessary
black smoke g. Internal engine problems,
loss of compression, Check for cause and correct
compression leaks Replace fuel
Bleed system
a. Air in fuel system Replace defective nozzle
b. Gasoline in fuel system
c. Air in high-pressure line Reset
d. Nozzle sticking open or with Replace pump
Clean or replace
low operating pressure
e. Engine problems
a. Timing off
b. Injection-pump trouble
c. Nozzle sticking open
d. Internal engine problems

Table 2.0 Diesel fuel injection trouble diagnosis chart

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 2.7.1: Identify the correct timing of fuel injection marks,
location and their purpose
Learning outcomes:
2. Set and install injection pump to engine
Learning Activity:
2.7 Identifying the correct timing of fuel injection marks, location and their purpose

Interpretation of timing marks.
a. Diesel Timing Marks Signifying letters

b. Diesel Timing Marks Signifying numbers

Read the injection timing point from the scale on the back of the crankshaft damper. If

the timing is correct, the timing mark should be at the value shown on the Vehicle
+
Emission Control Information label on the rocker cover - 2 degrees.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
ALT723301 Aug 15, 2003
Sept. 20, 2010 1

Information Sheet 2.7.1: Identify the correct timing of fuel injection marks,
location and their purpose
If the timing point determined differs from the standard value, minus 2 degrees, loosen
the four pump-to-flange plate nuts and rotate the pump (toward the crankcase to
advance the timing, away from the crankcase to retard it) to correct the difference. Each
mark on the injection pump timing scale represents 6 degrees. Tighten the flange plate
nuts and repeat the timing procedure to be sure the timing is correct.
Interpretation of timing marks.
a. Injection pump timing marks

b. Camshaft bushing timing mark

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Sept. 20, 2010 2

Worksheet 2.7.2: Identify fuel injection marks and location interpretation and
application
Learning outcomes:
2. Set and install injection pump to engine
Learning Activity:
2.7 Identifying fuel injection marks and location interpretation and application

Multiple Choice:

Direction: Select the correct answer and write the letter only in your answer sheet
provided for.

1. A diesel timing marks of gears signifying ___________.
a. canal
b. grooves
c. letters
d. pointer

2. Injection pump timing marks signifying ____________.
a. grooves
b. letters
c. pointer marks
d. threaded marks

3. Each marks on the injection pump timing scale represents what degrees?
a. 0 degree
b. 1 degree
c. 6 degrees
d. 20 degrees

4. Tighten the flange plate nuts and repeat the timing procedure to be sure the timing
is _______?
a. advance timing
b. correct
c. retard timing
d. wrong

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Worksheet 2.7.2: Identify fuel injection marks and location interpretation and
application

5. You can read the injection timing point from the scale on the back of.
a. crankshaft damper
b. engine block
c. timing chain cover
d. valve cover

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Nov. 28, 2003 Spt. 20, 2010 2

Worksheet 2.7.2: Identify fuel injection marks and location interpretation and
application

Answers Key:

1. A
2. A
3. C
4. B
5. A

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Nov. 28, 2003 Spt. 20, 2010 3

Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine
Learning outcomes:
2. Set and install injection pump to engine
Learning Activity:
2.8 Performing procedures in setting and installing injection pump to engine

Vehicles equipped with automatic transmission only:

1. Set no. 1 piston to TDC compression stroke by rotating the engine crankshaft until
It reaches the top most level with the intake and exhaust valves are closed.

2. Remove the three top cover screws from the replacement pump and install them into
the old pump (old pump Allen screws are longer and required for the TPS bracket).

Install the Throttle Position Sensor (TPS) bracket onto the replacement pump using
the Allen screws from the old pump. Insert the hex on the bottom of the TPS adapter
into the hex in the replacement pump throttle lever, making sure to engage the
adapter tang into the notched area of the bracket (Figure 2.0). Install the provided
TPS onto the bracket making sure to insert the slotted end of the TPS adapter into
the notched area of the TPS.

Figure 2.0

The TPS adapter must engage the throttle lever hex and the TPS notch with the
TPS and throttle levers spring loaded to the low idle position. (TPS will be adjusted
after pump installation is complete).

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

3. Spray the Top Dead Center (TDC) lock
pin with Mopar MP-50, PN 4549626, to
assure proper operation. Push the pin
in and pull it out several times until it
moves freely (Figure 2.1).

4. Remove the plastic plug at the lower
right of transmission adapter housing.
Use a barring tool such as Cummins
#337737 1, Miller #7471 A or Snap-On
#SP371 to rotate engine in a clockwise
direction (as viewed when facing the
front of the engine) (Figure 2.1).

Figure 2.1

Note: To rotate the engine in a clockwise direction, the barring tool must be rotated in a counterclockwise
direction as viewed from the front of the engine.

Locate the number one cylinder Top
Dead Center (TDC) position of the
compression stroke by watching the
key-way of the pump drive gear.
Slowly rotate the engine and push in
on the TDC lock pin when the drive
gear key-way approaches the 6:00
position. The engine will be at TDC of
the compression stroke when the lock
pin engages the hole in the cam gear
with the drive gear key-way at about
the 5:30 position (Figures 2.1 and 2.2).

Figure 2.2

Caution: Rotate engine with a barring tool only. Do NOT use starter motor. STOP barring the engine
IMMEDIATELY when the TDC lock pin "SNAPS" into the cam gear hole.

If the pump drive gear key-way passes the 4:30 position and the lock pin has not
engaged the cam gear, rotate the engine counterclockwise (rotate barring tool
clockwise) to the 7:00 O'clock position and repeat this step. DO NOT ENGAGE THE
LOCK PIN INTO THE CAM GEAR WHILE ROTATING THE ENGINE IN THE
COUNTERCLOCKWISE DIRECTION AS PUMP-TO-ENGINE TIMING WILL BE
AFFECTED.

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

5. Remove the barring tool, install the
plastic plug into the access hole and
pull the TDC lock pin out of the cam
gear hole. DO NOT MOVE THE
ENGINE ONCE THE NUMBER 1 TDC
COMPRESSION STROKE POSITION
IS SET.

Caution: Be sure to PULL TDC LOCK PIN OUT of
cam gear or pin will be sheared off.

Figure 2.3

6. Remove the old injection pump
mounting gasket. Clean the sealing
surface and install the provided gasket
(Figure 2.3).

7. Install the injection pump onto the
mounting studs and finger tighten the
three pump mounting nuts. The pump
must be free to rotate in the slots
(Figure 2.4). Make sure the key
doesn't fall into the gear housing.

Figure 2.4

Caution: To prevent slippage, spray the pump drive shaft and drive gear with Mopar Brake Cleaner, PN
4318037, to assure both are clean and free of all oil before installation.

Note: The shaft of the replacement pump is locked so that the key aligns with the drive gear key-way
when cylinder number one is at TDC of the compression stroke.

8. Install the pump drive gear nut Figure 2.5
and spring washer and torque to
18 ft-lbs (24 N*m). The pump may
rotate slightly when tightening the
pump drive nut because of the
gear lash between the pump drive
gear and cam gear. This
movement is acceptable
providing the entire pump moves
within the mounting stud slots and
there is no pump shaft-to-pump
housing movement (Figure 2.5).

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

Caution: DO NOT OVER TIGHTEN PUMP DRIVE GEAR NUT. The replacement pump shaft is locked in
position to eliminate the need to set pump-to-engine timing. This is NOT the final torque for the drive
gear.

Caution: DO NOT APPLY HEAVY ROTATIONAL FORCE on pump after gear backlash is removed as this
may preload the pump and affect pump-to-engine timing.

9. Gently rotate the fuel pump against
the direction of drive rotation to take
up any gear lash as shown in figure
2.6. Evenly tighten the pump mounting
stud nuts to 108 in-lbs (12 N*m), then
to a final torque of 18 ft-lbs (24 N*m).

Figure 2.6

10. Use a chisel or equivalent tool to
permanently mark the injection pump
mounting flange to match the existing
mark on the gear housing (Figure 2.7).

Figure 2.7

11. Unlock the fuel injection pump shaft by
loosening the lock screw as shown in
figure 2.8. Insert the special washer
(previously removed from the pump)
under the lock screw, then torque the
lock screw to 10 ft-lbs (13 N*m).

Figure 2.8

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

12. Tighten the pump drive gear retaining
nut to a final torque of 48 ft-lbs (65
N*m) as shown in figure 2.9. Remove
towel previously placed in drive gear
area.

Figure 2.9

13. Screw the oil filler base into the gear
housing cover, then screw the filler
tube into the base and tighten bracket
bolt (Figure 2.10).

Figure 2.10

14. Install the fuel drain manifold (banjo)
fitting to the pump using the new bolt
and sealing washers provided with the
replacement pump and torque bolt to
24 ft- lbs (32 N*m). Install the fuel tube
hold-down clamp bolt and torque to 18
ft-lbs (24 N*m) (Figure 2.11).

Note: The new banjo bolt provided with the
replacement pump has a calibrated bleed which is
matched to the replacement pump. DO NOT reuse
the old bolt or sealing washers.

Figure 2.11

15. Install the fuel supply line to the pump and torque fitting to 24 ft-lbs (32 N*m). Install
the other end of the supply line to the separator filter using the new sealing washers
provided. Leave this banjo bolt finger tight until after the fuel system has been
purged of air (Figure 2.12a and b).

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

Figure 2.12a Figure 2.12b

16. Install the high pressure fuel lines to
the pump and torque to 22 ft-lbs (30
N*m) (Figure 2.13). Install the fuel
lines to each injector, but DO NOT
tighten the fuel lines at the injectors
until the fuel system has been purged
of air.

Figure 2.13

Caution: Be sure that each fuel line is installed onto the same pump outlet port position from which it was
removed. Prevent the injection pump delivery valve holders from turning when installing the lines onto the
pump.

Note: THOROUGHLY clean the high pressure fuel lines with Mopar Brake Parts Cleaner, PN 4318037, to
make sure NO debris is present before installing the fuel lines onto the injectors or fuel pump.

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

17. Coat the four bolts used to secure the
fuel line support brackets with Mopar
Silicone Sealer (RTV), PN 4318025,
then install and torque the bolts to 18
ft-lbs (24 N*m) as shown in figure 2.14.
Install the oil dipstick and top engine
cover.

Figure 2.14
Note: Failure to apply sealant to the mounting bolts can result in an air intake leak.

18. Install the air fuel control tube (Figure
2.15).

19. Connect the electrical wires to the fuel
shut off valve, KSB solenoid and for
automatic transmission only, the
throttle position sensor.

Figure 2.15
Note: Two wires to fuel shut-off valve are interchangeable.

20. Swing the pump support bracket into
position and torque the 4 bolts to 18
ft-lbs (24 N*M) (Figure 2.16).

Figure 2.16

21. Install the throttle bracket and torque bolts to 1 8 ft-lbs (24 N*m). Install throttle

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

linkage onto pump lever ball stud and install the throttle return springs (Figure 2.17a
and b).

Figure 2.17a Figure 2.17b
Figure 2.18
22. Inspect the closed throttle and
wide open throttle accelerator
linkage travel stops. Verify that
the pump throttle lever contacts
the low idle speed screw in the
closed throttle position. With the
aid of an assistant, depress
accelerator pedal to the wide
open throttle position. Verify that
spring loaded breakover lever
has moved off the stop and is
against the break-over spring
(Figure 2.18).

If the pump stops are not as described, adjust the linkage using the "Throttle Linkage
Adjustment - Diesel Engine" procedure in the service manual.

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

23. Loosen the low pressure supply line
banjo bolt and bleed screw at the
separator filter and operate the hand
lever on the lift pump until the fuel
flowing from the fitting is free of air.
Then torque the separator filter banjo
bolt to 24 ft-lbs (32 N*m) and the bleed
screw to 72 in-lbs (8 N*m) (Figure
2.19).

Figure 2.19

24. Loosen all six fuel tube connections at the
injectors and operate the hand lever of the
lift pump until fuel is observed corning out
one of the high pressure fuel lines at the
injectors or until lift pump lever has been
pumped a minimum of 30 seconds,
whichever occurs first. (Figure 2.20).

25. Reconnect the battery.

Figure 2.20

26. With the fuel tube connections still loose at all injectors and the transmission in neutral or
park, crank the engine to allow entrapped air to bleed from the fuel lines (Figure 2.20).
Tighten all injector fuel line connections.

Caution: The pressure of the fuel in the line is sufficient to penetrate the skin (59,000 kpa/8,000
psi) and cause serious bodily harm. Wear safety goggles and adequate protective clothing and
do not allow contact with fuel spray when bleeding high pressure lines.

Caution: Place the transmission in neutral or park and set the parking brake before engaging
starter motor.

Caution: When using the starter motor to purge air from the system, do not engage it for more
than 30 seconds at a time and wait two minutes between engagements.

27. Start the engine and purge air from each injector fuel tube connection one line at a time until
the engine runs smoothly (Figure 2.20). Tighten all injector fuel line connections to 1 8 ft-lbs
(24 N*m) using an injector fuel line socket such as Mae #COBR17, Matco #WCFM1517 or
Snap-On #FRXM17.

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

Caution: 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.

27. Connect an optical tachometer to the engine such as Cummins #3377462, or Snap-On
#MT139 (1992-93 models may use DRB 11). Prepare the vehicle for an idle check as
follows:

• apply parking brake;
• make sure throttle lever is against the low idle speed stop screw;
• turn the air conditioner ON, if equipped;
• bring the engine to full operating temperature;
• automatic transmission in drive, if equipped;

Check and adjust the engine low idle
speed to 750 50 RPM, if necessary
(Figure 2.21).

Figure 2.21

28. Vehicles equipped with automatic
transmission only: Check and adjust the
throttle position sensor (TPS) as follows
(Figure 2.22):

• The injection pump throttle lever
must be in the low idle position and
the throttle lever must reach
breakover when the throttle is wide
open;

• turn the ignition key to the ON
position;

Figure 2.22

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

• connect the negative lead of the
voltmeter to a good ground (1991
1/2 - 1993 models may use DRB II);

• insert the positive lead of the
voltmeter to the center (output) wire
of the TPS electrical connector
(leave connector attached to TPS);

• with the throttle lever contacting the
low idle screw, the TPS output
voltage should be 1 volt ± 0.05 volt;

Figure 2.23

• adjust the closed throttle TPS setting, if required, by gently rotating the nylon adapter
until the correct voltage is obtained,

• open the throttle lever to the wide open position,
• the TPS output voltage should increase a minimum of 2.25 volts from the closed throttle

position voltage.
• if TPS required adjustment, disconnect the battery negative cable for 2 minutes to reset

adaptive memory, then reconnect the battery.

Injection Pump Drive Shaft and Drive Gear Assemblies, Cleaning, Inspection, and Repair

a. Cleaning. Clean all parts in an approved cleaning solvent and dry thoroughly.

b. Inspection and Repair.

1. Inspect the bearings for looseness, cracks, or wear. Replace defective bearings.

2. Inspect the gears for chipped, cracked, worn, or damaged teeth. Replace a defective
gear.

3. Inspect all threaded parts for burred or damaged threads. Replace a defective part as
necessary.

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Job Sheet 2.8.1: Perform procedures in setting and installing injection pump to
engine

Pump Drive Shaft and Drive Gear Assemblies Reassembly and Installation

a. Reassembly.

1. Refer to figure 2.9, and reassemble the injection pump drive gear in the reverse order.
Note. Install the washer (10), bearing (9), spacer (8), and bearing (7) on the shaft (6) and
install the assembled shaft in the housing (12).

2. Refer to figure 2.23, and reassemble the injection pump drive shaft in the reverse order.
Note. Install the bearing (8) on the shaft (7) and install the assembled shaft and bearing
in the cover (12).

b. Installation.

1. Refer to figure 2.8, and install the injection pump drive shaft and drive gear assembly on
the engine.

2. Install the fuel injection pump and governor assembly.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 3.1.1: Identify the components and functions of timing device

Learning outcomes:
3. Inspect injection timing
Learning Activity:
3.1 Identifying components and functions of timing device

Description:

A large percentage of fuel injection pumps have timing devices incorporated in them as
shown in figure 3.0. Varying the time when fuel injection begins will improve diesel engine
performance and fuel economy, for the same reason that varying spark timing will improve the
performance of a gasoline engine.

Fig. 3.0 Diesel injection pump timing device

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 3.1.1: Identify the components and functions of timing device

1. The timing device usually consists of an aluminum casting with mounting flanges at both
ends. A bore in the housing guides and supports the spider assembly. A timing opening, with a
cover, is located in the top of the housing and is used to observe the position of the timing
pointer in relation to the timing mark on the timing device hub during injection pump timing
procedures.

2. The timing device hub, with external left-hand helical splines for engaging the internal
helical splines of the sliding gear, has a tapered bore and keyway. The hub is secured to the
camshaft extension by a woodruff key, nut, and setscrew. The hub is usually counter bored to
receive the timing device springs. The springs oppose the flyweight forces of the weight and
spider assembly.

3. The weight and spider assembly has external right-hand helical splines which mesh with
the internal helical splines of the sliding gear. The splined end is machined to receive the end
play spacer. Three flyweights are pinned to a flange adjacent to the splines. The weight and
spider thrust plate, located between the flange and the timing device housing, carries the back
thrust of the flyweights and prevents housing wear.

4. The sliding gear has internal left-hand helical splines at one end and internal right-hand
helical splines at the other, and meshes with the external splines of both the weight and spider
assembly and the timing device hub. Correct assembly of the spline train is ensured by a wide
land on both the hub and weight and the spider assembly. The sliding gear has a missing tooth
on each set of internal splines to receive the wide lands.

Three arms extend from the outer surface of the sliding gear to provide seats for the three
timing device springs. The force on these springs is controlled by a sliding gear spacer.

Operation:

1. As the engine rotates the weight and spider assembly, centrifugal force opens the
flyweights from their collapsed position against the force of the three timing device
springs see below figure 3.1.

2. As the flyweights swing out, the sliding gear is forced toward the timing device hub.
3. The longitudinal movement of the sliding gear on its helical spline causes a slight

change in the rotational relationship of the injection pump to the engine, causing
injection to begin slightly earlier in the power stroke.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Information Sheet 3.1.1: Identify the components and functions of timing device
Figure 3.1. Actions of the flyweights during engine operation.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Worksheet 3.1.2 : Identify of components and functions of timing device
Learning outcomes:
3.’ Inspect injection timing
Learning Activity:
3.2 Identifying of components and functions of timing device

Identification Type:

Instruction: Identify the parts of timing device of fuel injection system as indicated in the
following numbers below.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Worksheet 3.1.2 : Identify of components and functions of timing device

Answers Key:

1. Sliding gear spacer
2. Timing cover
3. Timing pointer
4. Timing device spring
5. End play spacer
6. Sliding gear
7. Timing device hub
8. Flyweight
9. Weight and spider assembly
10. Weight and spider thrust plate

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Operation Sheet 3.2.1: Perform procedures in inspecting injection timing

Learning outcomes:
3 Inspect Injection Timing
Learning Activity :
3.2 Performing procedures in inspecting injection timing

Note: Unless major repair work is done on the engine, timing should not be required.

Four cylinder firing order - 1 - 3 - 4 - 2

Procedure:

1. Remove fuel lines from injector pump fittings on injector pump (Tool C).

2. Pull decompression lever so that it will remain in the decompression position. No
decompression lever on Model-12

3. Open throttle fully.

4. Energize electric fuel pump and turn engine over with starter to ensure that fuel is
coming out of each injector pump opening. Have clean rags around opening to soak
up fuel.

5. Wipe off any fuel on injector pump body and the top of each injector opening.

6. Turn crankshaft over by hand, being careful not to damage spline on end of
crankshaft. Engine rotation will be clockwise. STOP IMMEDIATELY at the first sign
of fuel movement in the injector pump fuel fitting, for whichever injector pump is
being checked. (No. 1 injector pump is the closest to the V-belt end of the engine).

7. Remove cover from flywheel timing mark inspection hold located inside of left
engine mount (Tool B).

8. Check alignment of mark on flywheel with the timing pointer on the wall of the
inspection hole. The 1-Fl mark on the flywheel represents fuel injection of No. 1
cylinder. 2-Fl represents No. 2 cylinder, etc.

9. If timing pointer and the flywheel marking 1-Fl is aligned then No. 1 cylinder is
properly timed for fuel injection and should require no adjustment. The same will be
true for No. 2, No. 3 and No. 4 cylinders if the above steps are followed.

10. In order to determine if timing is off, or if the injection pump is faulty, it is necessary
to recheck the timing for each cylinder two or three times.

11. If there are variations in repeatability in the alignment of pointer and timing mark, a
faulty fuel injector pump may be suspected.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Operation Sheet 3.2.1: Perform procedures in inspecting injection timing

12. If timing marks repeat to same location but are off 3/16" or more above or below the
pointer, this indicates that the engine must be retimed.

If alignment of the timing mark is not within 3/16" above or below the pointer, the
above steps must be taken to time the engine. If the timing is found to be
satisfactory, then reconnect all fuel lines and fittings and tighten.

The fuel system must be bled before the engine will operate properly.

Code No. Perform Diesel Engine Tune Up Date: Developed Date: Revised Page #
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Sept. 20, 2010 2

Job Sheet 4.1.1: Perform the procedures in bleeding injection system components

Learning outcomes:
4. Bleed injection system components
Learning Activity:
4.1 Performing procedures in bleeding injection system components

It will be necessary to bleed the fuel system to achieve a steady air free flow of fuel if
any of the following have occurred.
1. Running out of fuel.
2. If fuel shut off valve is left closed and engine runs out of fuel.
3. Replacing fuel filter.
4. Fuel injector nozzle or injector pump repair.
5. After repairing or replacing any fuel line.
6. Before putting engine back into service in the spring, if fuel system has been drained.
7. Replacement of electric or mechanical fuel pump.
8. Any time air is permitted to enter the fuel system.

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Job Sheet 4.1.1: Perform the procedures in bleeding injection system components

BLEEDING PROCEDURE:

Be sure to have some means available to catch or absorb any fuel escaping during the
bleeding process so that it will not accumulate in the engine compartment or bilge.

1. Be sure there is a sufficient supply of fuel in the fuel tank.

2. Open the fuel shut-off valve at the tank.

3. Start the electric fuel pump by turning the ignition key to the "ON" position on models
18, 20, 25, 30, 50, all models after 1986.

4. Model 15 has a mechanical fuel pump. Therefore with decompression on, turn engine
over with starter. Crank at 10 second intervals while doing steps #5 and 7.

5. Slowly loosen the air bleed plug on the fuel filter, letting air escape until an air free flow
of fuel is evident. (1986 models see item 7).

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