fuel ISUZU TROOPER 1995 Workshop Manual

6E2-118 DRIVEABILITV AND EMISSIONS
FUEL METERING SYSTEM COMPONENTS
The fuel metering system (Fig. 6E2-68) consists of the
following components:
• Fuel supply components (fuel tank, pump and
lines).
• Fuel
pump electrical circuit.
• Fuel rail assembly, including:
-Fuel pressure control valve
• Throttle
body assembly, including:
-Idle Air Control valve
-Throttle Position Sensor
engine
sensors
• Fuel • :pump : ........
Fuel tank
Fig. 6E2-68
FUEL SUPPL V SYSTEM
The fuel supply is stored in the fuel tank. An electric
fuel
pump, located in the fuel tank with the gage
sending unit, pumps
fuel through an in-line fuel filter to
the
fuel rail assembly. The pump is designed to
provide
fuel at a pressure above the pressure needed
by the injectors. A fuel pressure control valve, an
integral part of the fuel rail assembly, keeps fuel
available
to the injectors at a controlled pressure.
Unused
fuel is returned to the fuel tank by a separate
line. See ENGINE FUEL (SECTION 6C) for replacement
procedures covering the fuel tank, fuel pump, in-line
filter
and fuel lines.
FUEL PUMP ELECTRICAL CIRCUIT
When the key is first turned "ON" without the engine
running, Engine
Control Module (ECM) will turn the fuel
pump relay "ON" for two seconds. This builds up the
fuel pressure quickly. lfthe engine is not started within
two seconds, the ECM will shut the fuel pump "OFF"
and wait until the engine starts. As soon as the engine
is cranked, the
ECM will turn the relay "ON" and run the
fuel pump.
An inoperative
fuel pump would cause a no start
condition. A
fuel pump which does not provide
enough pressure can
result in poor performance,
(refer to CHARTs A-5 and A-7).
FUEL RAIL ASSEMBL V
The fuel rail assembly (Fig. 6E2-69) is mounted to the
Inlet manifold, and performs several functions: It
positions the injectors in the cylinder head, it
distributes fuel evenly to the injectors, and it integrates
the
fuel pressure control valve into the fuel metering
system.
Fuel flow within the rail is shown in Fig. 6E2-
70.
Fig. 6E2-69
Fig. 6E2-70

FUEL INJECTORS
The multipart fuel injection injector assembly is a
solenoid-operated device, controlled
by the Engine
Control Module (ECM), that meters pressurized fuel to
a single engine cylinder.
The
ECM energizes the low impedance (2.0 ohms) for
DOHC or High impedance (12.2 ohms) for SOHC
solenoid to a normally closed ball valve. This allows
fuel
to flow into the top of the injector, past the ball
valve, and through a recessed
flow director plate at the
injector outlet (Fig. 6E2-71). The director plate has six
machined holes
that control the fuel flow, generating a
conical spray pattern
of finely atomized fuel at the
injector tip. Fuel
from the tip is directed at the intake
valve, causing
it to become further atomized and
vaporized before entering the combustion chamber.
An injector which is stuck partially open
would cause a
loss
of pressure after engine shut down. Also, an
extended crank times would be noticed on some
engines. Dieseling could also
occ!Jr because some fuel
could be delivered
to the engine after the ignition is
turned
"OFF".
FUEL INJECTOR DRIVER OPERATION
The method of turning the Fuel Injectors "ON" and
"OFF" is called a "Peak" and "Hold" Driver System.
The
ECM uses a transistor to "Peak" Injector to open it.
A second set
of Injector Drivers will "Hold" the Injectors
open for the calculated pulse width. The ECM has three
(3) Injector Drivers, they are labeled A, 8, and C inside
the
ECM. Injector Driver "A" is used to open the Injector
initially (Peak) and depending on available battery
positive voltage
Injector Drive "8" or "C" is used to
"Hold" the Injector for the amount of time necessary to
inject the proper amount of fuel into the cylinder. A
resistor module in part
of the Injector Driver circuits to
protect the Injector Drivers from high current (amps). If
one of the Driver circuits become "Open" the vehicle
will
not start. Diagnosis of the Injector driver circuits
are done
with Chart A-3 "Cranks But Won't Run" chart
in
SECTION 6E2-A of this service manual.
FUEL PRESSURE CONTROL VALVE
ASSEMBLY
The fuel pressure control valve is a diaphragm­
operated relief valve
with fuel pump pressure on one
side and regulator spring pressure and intake manifold
absolute pressure on the other (Fig. 6E2-72).
The function
of the regulator is to maintain a constant
pressure differential across the injectors at all times.
The fuel pressure control valve compensates
for
engine load by increasing fuel pressure as engine
vacuum drops.
The fuel pressure control valve is mounted at the end
ofthe fuel rail, and is serviced as a complete assembly.
The system operates in
an acceptable pressure range
of 280 to 320 kPa (41 to 46 psi) with engine running.
If the pressure is too low, poor performance and a
DRIVEABILITV AND EMISSIONS 6E2-119
diagnostic trouble code 44 could result. If the pressure
is too high, excess odor and a diagnostic trouble code
45 could result.
CHART A-7 has information on diagnosing fuel
pressure conditions.
11. Fuel inlet
Fig. 6E2-71
1. Solenoid assembly
Spacer
and
guide assembly
. Ball valve
8. Cover-pressure regulator 1. Vacuum tube
7.
6.
Seal · 0-ring
Base assembly
Fuel
outlet fitting
Fig. 6E2-72

6E2 120 DRIVEABILITY AND EMISSIONS
THROTTLE BODY (TB) ASSEMBLY
The Throttle Body (TB) assembly is attached to the
intake manifold air
plenum, and is used to control air
flow into the engine, thereby controlling engine output
(Fig. 6E2-73). The TB within the TB is opened by the
driver through the accelerator controls. During engine
idle, the
TB is almost closed, and air flow control is
handled by the Idle Air Control (lAC) valve, described
below. To prevent
TB icing during cool weather
operation, engine
coolant is directed through a engine
coolant tube, part
of the TB, the engine coolant then
circulates through internal passageways around the
throttle bore and returns via the return engine coolant
tube.
The
TB also provides the location for mounting the
Throttle Position
Sensor. Vacuum ports the located at,
above or
below the throttle body to generate vacuum
signal needed
by various components.
Idle Air Control (lAC) Valve
Engine idle speed is controlled by the Engine Control
Module (ECM) through the Idle Air Control (lAC) valve
mounted on the
TB. The ECM sends voltage pulses to
the lAC motor windings causing the lAC valve pintle to
move "IN" or "OUT" a given distance (a step or count)
for each pulse. The pintle movement controls the
airflow around the TBs, which in turn, controls engine
idle speed.
• The "controlled" or desired idle speed for all
engine operating conditions is programmed into
the
calibration of the ECM. The programmed
engine speeds are based on engine coolant
temperature, park/neutral position switch status,
vehicle speed, battery positive voltage, and air
conditioning pressure (if equipped).
• The ECM "learns" the proper lAC valve positions to
achieve warm, stabilized idle speeds (revolution
per minute), desired
for the various conditions
(Park/Neutral position
or Drive, air conditioning
"ON" or "OFF", if equipped). This information is
stored in
ECM "Keep Alive" memories
(information
is retained after ignition is "OFF"). All
other lAC valve positioning is calculated based on
these
memory values.
As a
result, engine variations due to wear and
variations in
minimum TB position (within limits)
do not affect engine idle speeds. This system
provides correct idle control under
all conditions.
This also means
that disconnecting power to the
ECM can result in incorrect idle control or
necessity to partially depress the accelerator
pedal
when starting until the ECM relearns idle
control. Refer to note regarding clearing
memory
in "ECM and Sensors," Section "6E2-C1 ".
•
Engine idle speed is a function of total airflow into
the engine based on
lAC valve pintle position plus
TB opening plus calibrated vacuum loss through
accessories.
• The minimum TB position is set at the factory with
a stop screw. This setting allows enough air flow
by the TB to cause the lAC valve pintle to be
positioned a calibrated
number of steps (counts),
from the seat, during "controlled" idle operation.
The
minimum TB position setting on this engine
should not be considered the
"minimum idle
speed", as on other fuel injected engines. The
throttle stop
screw is covered with a plug at the
factory
following adjustment.
U7 CAUTION:
VI Do not attempt to remove the protective cap and
readjust the stop screw before
reviewi~g t~e
"Minimum TB Position Check", later m th1s
section. Misadjustment may result in damage to
the lAC valve or TB.
Fig. 6E2-73
2. Throttle body assembly
3. Throttle position sensor (TPS)
• The ECM normally resets the lAC valve pintle
position once during each ignition cycle,
when
vehicle speed increases above 35 miles per hour
on moderate acceleration. During the reset, the
ECM commands the lAC valve pintle to retract
completely, then move
"IN" to the seated position
(to establish the zero
count position), and then
back
out to the desired position. If, after the reset,
the
ECM is able to control the idle speed within the
calibrated count range, the
lAC valve will not be
reset again until the ignition has been turned
"OFF", the engine restarted and the car then
driven above 35 mile per hour.
If the ECM is not
able to control idle speed within the calibrated
count range after the first reset, the
ECM assumes
the
lAC valve pintle position is "lost", and enables
another reset
to occur. This will continue until the
pintle position is relearned.
• If the lAC valve is suspected as being the cause of
improper idle speed, perform a functional check of
the lAC valve (CHART C-2C) as described later in
this section.
-----------------------------'
•

Throttle Position (TP) Sensor
The Throttle Position (TP) Sensor is mounted on the
side
of the throttle body opposite the throttle lever
assembly.
Its function is to sense the current throttle
body position and relay that information to the ECM.
Knowledge ofTP is needed by the ECM to generate the
proper injector pulse width.
If the TP sensor senses a
Wide
Open Throttle, a voltage signal indicating this
condition is transmitted to the
ECM. The ECM will
widen the injector pulse, or increase the repetition rate,
permitting increased fuel
flow to each for the six fuel
injectors located in the fuel fail. As the throttle shaft
rotates in response to
movement of the accelerator
pedal (opening
or closing of the throttle body), the
throttle shaft transmits throttle
movement to the TP
sensor. A potentiometer (variable resistor) within the
TP sensor assembly creates a voltage that varies in
response to
TP. By applying a reference voltage (+5
VDC) to the TP sensor input, a varying voltage
(reflecting
TP) is available at the TP sensor output. The
voltage
output from the TP sensor is sent to the ECM
for use in determining current TP.
For further information ofTP sensor, refer to "ECM and
Sensors", Section
"6E2-C1 ". The TP sensor is an auto
zeroing type and cannot
be adjusted.
DRIVEABILITY AND EMISSIONS 6E2-121
INDUCTION AIR CONTROL PLATE
SYSTEM (DOHC) (Fig. 6E2-74)
This system consists of the Induction Air control plate
valve mounted in the common chamber
duct and a
vacuum operated diaphragm
which moves the Induction Air
Control Plate linkage. The vacuum to the diaphragm is
turned
"ON" or "OFF" by a vacuum switching solenoid
which is electrically operated by the
ECM.
Refer to CHART C-20 for diagnosing the Induction air
control plate system.
Manifold vaccum
1
Vacuum actuator
Induction air control plate valve
(noma! open)
Fig. 6E2-74
Engine control module (ECM)
Ignition switch
Canister, EGR, A.I.R. solenoids
DIAGNOSIS
FUEL METERING SYSTEM
Some failures of this system will result in the symptom,
"Engine Cranks But Will Not Run". If this condition
exists, see CHART A-3. This chart will determine
if the
problem is caused by the ignition system,
ECM or fuel
pump circuit.
If it's determined to be a fuel problem.
CHART A-5
or A-7 will be used. This includes the
injectors, fuel pressure control valve, fuel
pump and
fuel pump relay. The fuel system
wiring schematic
diagram is covered on the facing page
of CHART A-5.
If a malfunction occurs in the fuel control system, it
usually results in either a rich or lean Heated Oxygen
Sensor (H02S) signal condition. This condition is
sensed by the
H02S and the ECM will change the fuel
calculation (injector pulse width) based on
H02S input.
The change made to the fuel calculation will be
indicated
by a change in the block learn values which
can be displayed on a
"Scan tool". The ideal block learn
values are around 128 counts.
If the H02S senses a
lean condition, the
ECM will add fuel, resulting in a
block learn value above 128 counts.
If the H02S senses
a rich condition, the
ECM will subtract fuel, resulting in
a block learn value below 128 counts.
Block learn values can vary greatly, depending on
temperature, altitude and individual engine
tolerances. The programmed range for block learn
values is
58 to 198. Values within this range indicate
the system is in
"control". If a system is operating near
the extremes
of the block learn range during normal vehicle
operation, and there is a driveability complaint,
the fuel metering system should be checked. Refer to
the diagnostic trouble code
45 chart on the facing page
for potential causes of a rich condition (low block learn
values). Refer to the diagnostic trouble code 44 chart
facing page
for potential causes of a lean condition
(high block learn values).
If a driveability symptom
exists, also refer to the particular symptom in
"Symptoms", Section "6E2-B" for additional items to
check.
FUEL SYSTEM PRESSURE TEST
A fuel system pressure test procedure is included in
CHART A-7 under
"Fuel System Diagnosis" in "Engine
Components/Wiring Diagrams/Diagnostic
Charts",
Section "6E2-A" diagnostic charts.
IDLE AIR CONTROL (lAC) VALVE
A "Scan tool" will display Idle Air Control (lAC) valve
position in
"Counts" or steps. "0" steps indicates the
ECM is commanding the lAC valve to be driven all the
way in, to a fully seated position. This condition is
usually caused by a vacuum leak.
The higher the number
of counts, the more air is being
allowed to pass the
lAC valve. A functional check of the
lAC valve system (CHART C-2C) is provided in this
section. Refer to
"Refer, Unstable, or Incorrect Idle,
Stalling"
in "Symptoms", Section "6E2-B" for other
possibilities
for the cause of idle problems.

6E2-122 DRIVEABILITV AND EMISSIONS
INDUCTION AIR CONTROL PLATE
SYSTEM
Refer to CHART C-2D to diagnose the Induction air
control plate system.
ON-VEHICLE SERVICE
FUEL PUMP RELAY
The fuel pump relay is mounted in the engine
compartment.
Other than checking for loose
connectors, the only service possible is replacement.
MUL TIPORT FUEL INJECTION
COMPONENTS
WCAUTION:
VI • To reduce the risk of fire and personal injury, it
is necessary to relieve the fuel system pressure
before servicing
fuel system components.
• After relieving system pressure, a small
amount of fuel may be released when servicing
fuel lines or connections. In order to reduce the
chance
of personal injury, cover fuel line
fittings with a shop towel before disconnecting,
to catch any
fuel that may leak out. Place the
towel in an approved container when
disconnect is completed.
Fuel Pressure Relief Procedure
1. Remove fuel cap.
2. Remove fuel pump relay from underhood relay
box.
3. Start engine and allow to stall.
4. Crank engine for additional 30 seconds.
5. Remove negative battery cable.
FUEL RAIL ASSEMBL V
An eight digit identification number is stamped on the
side
ofthe fuel rail (Fig. 6E2-75). Refer to this number if
servicing or part replacement is required.
Names
of component parts appear in the numbered
list on the disassembled view (Fig. 6E2-75).
'fCAUTION:
• Do not attempt to remove the fuel inlet fitting
on the
fuel rail, it is staked in place. To do so will
result
in damage to the fuel rail or to the internal
0-ring seal.
•
Do care in removing the fuel rail assembly, to
prevent damage to the injector
electrical
connector terminals and the injector spray tips.
• Prevent dirt and other contaminants from
entering open lines and passages. Fittings
should be capped, and holes plugged, during
servicing.
Before
removal, the fuel rail assembly may be
cleaned with a spray type engine cleaner,
following
package instructions. Do not
immerse fuel rails in liquid cleaning solvent.
Fig. 6E2-75
I'
---------------------'
•

DRIVEABILITY AND EMISSIONS 6E2-123
UNIT REPAIR
FUEL INJECTOR/RAIL
1 11
5
9
13
5 14
2 12 5
15
3
6
Fig. 6E2-76

6E2-124 DRIVEABILITV AND EMISSIONS
E) REMOVAL
Preparation: • Engine hood
• Battery negative cable
1.
Air cleaner assy
2.
Accelerator pedal cable
•
Disconnect from throttle body and cable
brackets.
3. Canister vacuum hose
• Disconnect from vacuum switch valve (VSV).
4. Vacuum booster hose
• Disconnect from Common chamber duct.
5. Connectors
• Disconnect idle air control valve, throttle
position sensor, manifold absolute pressure,
canister
VSV, exhaust gas recirculation (EGR)
VSV, intake air temperature and VSV.
6. High tension cable
• Remove from cylinder heads.
7. Electronic ignition (EI) module assy
• Disconnect 3 connector from El module.
• Remove 3 bolts from El bracket and El assy.
8.
Throttle body (TB)
• Remove 4 bolts from TB.
9. Vacuum hoses
• Disconnect canister VSV and EGR VSV vacuum
hose
from TB.
10. Fuel pressure control valve vacuum hose
• Disconnect from common chamber duct.
11.
PCV hose
• Disconnect from common chamber duct.
12.
Evaporate emission canister purge hose
• Disconnect from common chamber duct.
13.
EGR valve assy
• Remove 4 bolts from common chamber duct
and exhaust manifold.
14.
Common chamber duct
• Remove 4 bolts, 4 nuts and 3 duct bracket fixing
bolts.
• Remove ground cable fixing bolt from rear of
common chamber duct.
15.
Common chamber
• Remove 6 bolts and 2 nuts.
• Remove common chamber bracket fixing bolts
from rear of common chamber.
16. Fuel
hose
• Feed and return hose from fuel pipe and 2 fixing
bolts
from cylinder head. 17.
Fuel
rail assembly
• Remove fuel injector connector.
• Remove fuel rail fixing bolts.
• Remove fuel rail assy.
j .. !•l DISASSEMBL V
NOTE:
• If
an injector becomes separated from the rail and
remains in the cylinder head, both injector
0-ring
seals and the retainer clip must be replaced.
1.
Regulator attaching screw
2. Fuel pressure control valve assembly
3. Injector retainer clip (Fig. 6E2-77)
4.
Multipart fuel injection injector assembly
5. Fuel rail
Fig. 6E2-77
l•! .. j REASSEMBL V
5. Fuel rail
4. Multipart fuel injection injector assembly
• Lubricate new injector 0-ring seal with engine
oil, and
install on injectors.
3.
Injector retainer clip
2. Fuel pressure control valve assembly
1. Regulator attaching screw
l·u·jiNSTALLATION
To install, follow the removal steps in the reverse
order.
THROTTLE BODY ASSEMBL V
The TB assembly repair procedures cover component
replacement
with the unit on the vehicle. However, TB
replacement requires that the complete unit be
removed from the engine.
The last three digits
of the eight digit identification
number are stamped on the
TB casting, next to the
throttle stop screw (Fig. 6E2-78). The part number
begins
with "17091 ... " Refer to this number if servicing
or part replacement is required.
•

1~1 Measure (If Installing a New Idle Air
Control (lAC) Valve) (Fig. 6E2-82)
• Distance between tip of idle air control (lAC)
valve pintle and mounting flange.
-
If greater than 28 mm, finger pressure to
slowly retract the pintle. The force required
to retract the pintle
of a new valve will not
cause damage to the valve.
Fig. 6E2-82
E) INSTALLATION
3. lAC valve assembly
2. lAC valve attaching screw
1. lAC valve electrical connector
MINIMUM THROTTLE BODY (TB)
POSITION CHECK
The minimum throttle body (TB) position (throttle stop
screw) adjustment
for the 3.2L should not be
considered the
"minimum idle speed", as on other fuel
injected engines. Low internal friction and provision
for slight production variations and various operation
altitudes resulted in a calibrated
minimum TB position
which is too
low to allow most engines to idle. The
adjustment is preset at the factory and no further
adjustment should be necessary.
If there is a complaint of high idle speed, vacuum leaks
should be considered the
most likely cause. Because
the Engine
Control Module (ECM) "learns" Idle lAC, it is
even less likely
that a stalling complaint would be due
to
an incorrect minimum TB position. In either case,
the
"Symptoms," Section "6E2-B" and lAC valve check
CHART C-2C should be referred to.
If it is determined that the minimum TB position is
suspect,
be sure lAC valve is not "lost'' (not actually at
the location indicated by current
lAC "counts"). The
lAC valve could be "lost" if ECM power has been
interrupted
with the ignition "ON", or the lAC valve has
been disconnected
with the engine running since the
last reset,
as described previously in this section in the
"lAC Valve Assembly" general description.
DRIVEABILITY AND EMISSIONS 6E2-127
The minimum TB position may be checked using the
following procedure.
1. Block drive wheels, and apply parking brake.
2. Connect "Scan tool" to the data link connector.
3. Start engine and allow to reach operating
temperature (about
go•q and "Closed Loop".
4. A/T-shift to DRIVE ("D") and then back to neutral
("N").
5. Select power steering pressure switch input on
"Scan tool". With air conditioning and all electrical
accessories
"OFF", transmission in natural, "Scan
tool" should read "OFF" or "NORMAL". (If not,
refer to
CHART C-1 E to diagnose and repair faulty
power steering pressure switch circuit before
proceeding).
Allow idle to stabilize.
6. Select lAC valve display on "Scan tool", and read
lAC valve counts. If between 5-45 counts, the
minimum
TB position adjustment is acceptable. It
is important to allow idle speed to stabilize to
assure correct counts are determined.
If counts in step 6 are too low, check for intake air
(vacuum) leaks at hoses,
TB and intake manifold or
damaged throttle lever and correct as necessary.
Also, refer to
CHART C-2C facing page "Diagnostic
Aids". If no vacuum leaks or other cause of
excessive air into the intake are found, it may be
necessary
to replace the TB to correct the low idle
speed problem. Refer to
"TB Replacement" in this
section.
If counts in Step 6 are too high, check for damaged
throttle lever or airflow restriction by the
TB. If no
problem is evident, remove inlet air
duct at the TB,
and
clean residue from inside of TB bore and from
edges of TB using carburetor cleaner and a shop
towel. (Do Not use a cleaner that contains methyl
ethyl ketone.
It is an extremely strong solvent, and
not necessary for this type of deposit). Re-check
"Scan tool" lAC valve counts, per the preceding
procedure.
If counts are still too high it may be necessary to
replace the
lAC valve or the TB assembly, If no
vacuum leaks are indicated
or engine loads are
present.
Minimum Throttle Body (TB) Position
(Non-Adjustable)
\fl CAUTION:
VI • It is extremely unlikely that this adjustment will
ever be necessary on a TB that has not been
tampered
with after production! If idle
revolution per minute is low, you may need
to
replace the TB to correct the low idle speed.

6E2-128 DRIVEABILITY AND EMISSIONS
CHART C-2A
INJECTOR BALANCE TEST
The injector balance tester is a tool used to turn the injector on for a precise amount of time, thus spraying a
measured
amount of fuel into the manifold. This causes a drop in fuel rail pressure that we can record and
compare between each injector.
All injectors should have the same amount of pressure drop (± 10 kPa). Any
injector with a pressure drop that is 10 kPa (or more) greater or less than the average drop of the other injectors
should be considered faulty and replaced.
NOTE: It will be necessary to remove the intake plenum to perform this procedure. Refer to intake plenum
remove procedure in this section. It will also be necessary to install the Intake Manifold Diagnostic Plate J
39185 to enable the engine to be run with the plenum removed. Refer to Chart A-8 in Section "6E2-A" of
this service manual.
STEP 1
Engine "cool down" period (10 minutes) is necessary to avoid irregular readings due to "Hot Soak" fuel boiling.
With ignition "OFF" connect fuel gauge J 347301 or equivalent to fuel pressure tap. Wrap a shop towel around
fitting
while connecting gage to avoid fuel spillage. Refer to Chart A-7 in Section 6E2-A, Page 1 of 3.
Disconnect harness connectors at all injectors, and connect injector tester J 34730-3, or equivalent, to one injector.
Follow manufacturers instructions for use of adaptor harness. Ignition must be "OFF" at least 10 seconds to
complete engine control module shutdown cycle. Fuel pump should run about 2 seconds after ignition is turned
"ON". At this point, insert clear tubing attached to vent valve into a operation. Repeat this step until all air is bled
from gauge.
STEP 2
Turn ignition "OFF" for 10 seconds and then "ON" again to get fuel pressure to its maximum. Record this initial
pressure reading. Energize tester one time and note pressure drop at its lowest point (Disregard any slight
pressure increase after drop hits low point). By subtracting this second pressure reading from the initial pressure, ~
we have the actual amount of injector pressure drop.
STEP 3
Repeat step 2 on each injector and compare the amount of drop. Usually, good injectors will have virtually the
same drop. Retest any injector
that has a pressure difference of 10 kPa, either more or less than the average of the
other injectors on the engine.
Replace any injector that also fails the retest. If the pressure drop of all injectors is
within 10 kPa of this average, the injectors appear to be following properly.
Reconnect them and review "Symptoms", Section "6E3-B".
NOTE: The entire test should NOT be repeated more than once without running the engine to prevent flooding.
(This includes any retest on faulty injectors). To run the engine with the intake plenum removed use the
Intake Manifold Diagnostic Plate.
•

DRIVEABILITY AND EMISSIONS 6E2-129
CHART C-2A
INJECTOR BALANCE TEST
NOTE: The entire test should NOT be repeated more than once without running the engine to prevent flooding.
(This includes any retest on faulty injectors).
The
fuel pressure test in Section "A" Chart A-7, should be completed prior to this test.
Step 1. If engine is at operating temperature, allow a 10 minute "cool down" period then connect fuel pressure
gauge and injector tester.
1. Ignition "OFF".
2. Connect fuel pressure gauge and injector tester.
3. Ignition "ON".
4. Bleed off air gauge. Repeat until all air is bled from gauge.
Step 2. Run test:
Step 3.
1. Ignition "OFF" for 1 0 seconds.
2. Ignition "ON". Record gauge pressure. (Pressure must hold steady, if not see the Fuel System
diagnosis, Chart A-7, in Section "A").
3. Turn injector on, by depressing button on injector tester, and note pressure at the instant the gauge
needle stops.
1. Repeat step 2 on all injectors and record pressure drop on each. Retest injectors that appear faulty
(Any injectors that have a 10 kPa (1.5 psi) difference, either more or less, in pressure from the
average).
If no problem is found, review "symptoms" Section "8".
Injector connector
Tester J34730-3
Fig. 6E2-83
Gauge J34730-1
BATTERY
EXAMPLE
CYLINDER 1 2
3 4
5 6 7 8
1ST
READING 293 kPa 293 kPa 293 kPa 293 kPa 293 kPa 293 kPa 293 kPa 293 kPa
(43 psi) (43 psi) (43 psi) (43 psi) (43 psi) (43 psi) (43 psi) (43 psi)
2ND
READING 131 kPa 131 kPa 131 kPa 115 kPa 131 kPa 145 kPa 131 kPa 131 kPa
(19 psi) (19 psi) (19 psi) (17 psi) (19 psi) (21 psi) (19 psi) (19
psi)
AMOUNT
OF DROP 162 kPa 162 kPa 162 kPa 178 kPa 162 kPa 148 kPa 162 kPa 162 kPa
(24 psi) (24 psi)
(24 psi) (26
psi) (24 psi) (21 psi) (24 psi) (24 psi)
OK OK OK FAULTY, RICH OK FAULTY, LEAN OK OK
(TOO MUCH (TOO LITTLE
FUEL DROP) FUEL DROP)