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Dodge Sprinter. Manual - part 251

OPERATION

The injector operation can be subdivided into four

operating states with the engine running and the
high-pressure pump generating pressure:

• Injector closed (with high pressure applied)

• Injector opens (start of injection)

• Injector opened fully

• Injector closes (end of injection)

Injector closed (with high pressure applied)

With the injector closed (at-rest state), the solenoid

valve is not energized and is therefore closed. With
the bleed orifice closed, the valve spring forces the
armature’s ball onto the bleed-orifice seat. The rail’s
high pressure build up in the valve control chamber,
and the same pressure is also present in the nozzle’s
chamber volume. The rail pressure applied at the
control plunger’s end face, together with the force of
the nozzle spring, maintain the nozzle in the closed

Fig. 10 FUEL INJECTOR

1 - FUEL INJECTOR
2 - NOZZLE
3 - FUEL INLET FITTING
4 - ELECTRICAL CONNECTION

Fig. 11 INJECTOR COMPONENTS

1 - INJECTOR CLOSED (AT-REST STATUS)
2 - ELECTRICAL CONNECTION
3 - TRIGGERING ELEMENT (SOLENOID VALVE)
4 - FUEL INLET (HIGH PRESSURE) FROM THE RAIL
5 - VALVE BALL
6 - BLEED ORIFICE
7 - FEED ORIFICE
8 - VALVE CONTROL CHAMBER
9 - VALVE CONTROL PLUNGER
10 - FEED PASSAGE TO THE NOZZLE
11 - NOZZLE NEEDLE

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FUEL INJECTION

position against the opening forces applied to its
pressure stage (Fig. 11).

Injector opens (start of injection)

The solenoid valve is energized with the pickup

current which serves to ensure that it open quickly.
The force exerted by the triggered solenoid now
exceeds that of the valve spring and the armature
opens the bleed orifice. Almost immediately, the high-
level pick-up current is reduced to the lower holding
current required for the electromagnet. This is possi-
ble due to the magnetic circuit’s air gap now being
smaller. When the bleed orifice opens, fuel can flow
from the valve control chamber into the cavity situ-
ated above it, and from there via the fuel return to
the tank. The bleed orifice prevents complete pres-
sure balance, and the pressure in the valve control
chamber sinks as a result. This leads to the pressure
in the valve-control chamber being lower than that in
the nozzle’s chamber volume which is still at the
same pressure level as the rail. The reduced pressure
in the valve-control chamber causes a reduction in
the force exerted on the control plunger, the nozzle
needle open as a result, and injection starts (Fig. 11).

Injector opens fully

The control plunger reaches its upper stop where it

remains supported by a cushion of fuel which is gen-
erated by the flow of fuel between the bleed and feed
orifices. The injector nozzle has now opened fully,
and the fuel is injected into the combustion chamber
at a pressure almost equal to that in the fuel rail
(Fig. 11).

Injector closes (end of injection)

As soon as the solenoid valve is no longer trig-

gered, the valve spring forces the armature down-
wards and the ball closes the bleed orifice. The
armature is a 2–piece design. Here, although the
armature plate is guided by a driver shoulder in its
downward movement, it can “overspring” with the
return spring so that it exerts no downwards-acting
forces on the armature and the ball. The closing of
the bleed orifice lead to pressure build up in the con-
trol chamber via the input from the feed orifice. This
pressure is the same as that in the rail and exerts an
increased force on the control plunger through its
end face. This force, together with that of the spring,
now exceeds the force exerted by the chamber volume
and the nozzle needle closes. Injection ceases as soon
as the nozzle needle comes up against its bottom stop
again (Fig. 11).

STANDARD PROCEDURE

STANDARD PROCEDURE - INJECTOR CLASSI-
FICATION

NOTE: Fuel Injectors have different flow rates.
When ALL injectors are removed, re-enter all injec-
tor six digit codes.

The

classification

injectors

into

classes

describes the quantity characteristic of the injector.
This will make it possible in the future to match the
engine software to the tolerances of the injector
within a more narrowly graduated range. Classifica-
tion can be clearly recognized, and assigned only by
means of a DRBIII

Classified injectors can be recognized by the six-

digit alphanumeric code or part number and identifi-
cation on the magnetic head (circle with a number
between 1 and 3 inside) (Fig. 12). The number corre-
sponds to the classification stage.

These general conditions equally apply if, as a

result of replacing an engine, carrying out repairs to
the cylinder head etc., the cylinder selective assign-
ment of the injectors or the engine control module
assignment may have changed. If proper attention is
not paid to the classification on these vehicles drive-
ability and smoking concerns could result.

If an injector is replaced, it is then necessary to

assign the classification number to the corresponding
cylinder with the DRBIII

t in the control module.

Fig. 12 INJECTOR CLASSIFICATION MARKINGS

1 - ELECTRICAL CONNECTOR
2 - SIX-DIGIT ALPHANUMERIC CODE

FUEL INJECTION

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INJECTOR CLASSIFICATION PROCEDURE

(1) Turn ignition switch “ON”.
(2) Using a DRB III

t and select ENGINE then

MISCELLANEOUS.

(3) Select LEARN INJECTORS.
(4) Using the up and down arrows, scroll to the

appropriate injector.

(5) Using the right and left arrows, set injector to

proper classification.

(6) Once injectors are classified, cycle ignition to

complete.

CLEANING FUEL INJECTORS

NOTE: Before cleaning the injector recesses, seal
the injector holes in the injector recesses with the
appropriate pin to prevent debris from falling into
the recesses and entering the motor.

(1) Seal the injector holes inside the cylinder head

recesses.

(2) Wipe out injector recesses with a non-woven

cloth, then clean with a cylinder brush.

(3) Clean the bottom of the cylinder recess with a

round brush.

(4) Blow out the recess and clean again with a

non-woven cloth and cover over.

(5) Perform these steps for each injector recess.

NOTE: DO NOT clean the tip of the injector with a
wire brush. Use a non - woven cloth.

(6) Clean injector body with a wire brush.
(7) Clean injector tips with a non-woven cloth.

NOTE: Do Not apply antiseize lubricant to the injec-
tor nozzle area.

(8) Grease injector body with anti seize lubricant.

NOTE: Always replace the seals that seal off the
injectors at the cylinder head to the combustion
chamber and replace the retaining screws.

REMOVAL

WARNING: NO SPARKS, OPEN FLAMES OR SMOK-
ING. RISK OF POISONING FROM INHALING AND
SWALLOWING FUEL. RISK OF INJURY TO EYES
AND SKIN FROM CONTACT WITH FUEL. POUR
FUELS ONLY INTO SUITABLE AND APPROPRI-
ATELY MARKED CONTAINERS. WEAR PROTECTIVE
CLOTHING.

NOTE: When removing injectors, the seal rings and
retaining stretch bolts must always be replaced.
Coat the injector body with the anti-seize com-

pound before installing. Keep lubricant away from
the injector nozzle.

(1) Disconnect negative battery cable.
(2) Remove engine cover (Refer to 9 - ENGINE -

REMOVAL).

(3) Remove the fuel return hose locking clamps at

the injector and remove return hose.

(4) Disconnect the injector electrical connector

(Fig. 13).

NOTE: Counterhold injection lines with wrench
socket at threaded connections of injectors.

(5) Disconnect fuel injector high pressure line (Fig.

13).

(6) Remove fuel injector retaining bolt and tension

claw, then remove the injector and seal (Fig. 13).

NOTE: If injectors are tight, remove with extraction
claw in place of tensioning claw. If extraction claw
contacts cylinder head cover, remove cylinder head
cover. If necessary, remove injectors with threaded
adaptor and discard injector.

(7) Remove injectors (Fig. 13).

(8) Clean injectors and recesses (Refer to 14 -

FUEL SYSTEM/FUEL INJECTION/FUEL INJEC-
TOR - STANDARD PROCEDURE).

Fig. 13 FUEL INJECTOR REMOVAL / INSTALLATION

1 - FUEL INJECTOR RETURN LINE
2 - RETAINING CLIP
3 - INJECTOR HIGH PRESSURE LINE
4 - INJECTOR SEAL
5 - FUEL INJECTOR
6 - TENSIONING CLAW
7 - SPECIAL TOOLS #8938 AND # 8937

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FUEL INJECTION

INSTALLATION

NOTE: When removing injectors, the seal rings and
retaining stretch bolts must always be replaced.
Coat the injector body with the anti-seize com-
pound before installing. Keep lubricant away from
the injector nozzle.

(1) Clean injectors and recesses (Refer to 14 -

FUEL SYSTEM/FUEL INJECTION/FUEL INJEC-
TOR - STANDARD PROCEDURE).

(2) Coat injector body with anti seize lubricant

then install injectors with new seals.

(3) Install tensioning claws with new screws at

injectors. Tighten screws in two stages, 7 N·m (62
lbs. in.) then 90° (Fig. 13).

NOTE: If locking clamp has been pulled off at injec-
tor, the locking clamp must be replaced.

(4) Position fuel return line at injectors and secure

locking clamps (Fig. 13).

NOTE: Counterhold injection lines with wrench
socket at threaded connections of injectors. DO
NOT over tighten.

(5) Install high pressure injection lines (Refer to

14 - FUEL SYSTEM/FUEL DELIVERY/FUEL LINES
- INSTALLATION).

(6) Reconnect injector electrical connectors (Fig.

13).

(7) Connect negative battery cable.

NOTE: Fuel Injectors have different flow rates.
When injectors are removed, re-enter all injector six
digit codes.

(8) Program all injector codes into the ECM using

the scan tool.

(9) Start engine, allow to run, turn engine off and

inspect for leaks (Refer to 14 - FUEL SYSTEM -
WARNING).

CAUTION: Care must be taken when installing the
engine cover. Assure the proper routing of the fuel
injector return fuel hose to the banjo bolt fitting in
the left rear corner of the cover. Failure to do so
may pinch or damage the hose causing fuel leakage
or a driveability concern.

(10) Install engine cover (Refer to 9 - ENGINE -

INSTALLATION)..

FUEL PRESSURE SENSOR

DESCRIPTION

The fuel rail pressure sensor measures the current

fuel rail pressure and supplies an appropriate voltage
signal to the ECM. The non-constant fuel system
pressure influences the position of the internal dia-
phragm. This results in a variation in the electrical
resistance which is analyzed by the ECM.

OPERATION

The fuel rail pressure sensor measures the current

fuel rail pressure and sends a voltage signal to the
ECM. The ECM then actuates the fuel rail pressure
control valve until the desired rail pressure is
achieved.

REMOVAL

(1)

(Refer to 14 - FUEL SYSTEM/FUEL INJEC-

TION - WARNING) Disconnect the negative battery
cable.

(2) Remove the mixing housing.
(3) Unplug the sensor (Fig. 14).
(4) Counter-hold the threaded connection at the

fuel rail and unscrew the sensor (Fig. 14).

Fig. 14 FUEL RAIL PRESSURE SENSOR

1 - WIRING CONNECTOR
2 - FUEL RAIL PRESSURE SENSOR
3 - SEALING RING
4 - FUEL RAIL

FUEL INJECTION

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