1998 ISUZU TROOPER fuel pressure

6E±277 ENGINE DRIVEABILITY AND EMISSIONS
Excessive Exhaust Emissions or Odors Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Vehicle fails an emission test. Vehicle has excessive
ªrotten eggº smell. (Excessive odors do not necessarily
indicate excessive emissions.)
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
ÐGo to Step 12Go to Step 3
3Was a thorough visual/physical check performed?
ÐGo to Step 4
Go to
Visual/Physic
al Check
41. Check for vacuum leaks. Check vacuum lines,
intake manifold, throttle body, etc.
2. If a problem is found, repair as necessary.
Were any vacuum leaks located?
ÐGo to Step 12Go to Step 5
51. Check the fuel cap for proper installation.
2. Secure the fuel cap if necessary.
Was the fuel cap installed properly?
ÐGo to Step 6Go to Step 12
61. Check the fuel pressure. Perform the procedure in
Fuel System Pressure Test.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 7
71. Check for a faulty, plugged, or incorrectly installed
crankcase ventilation valve; also check the
crankcase ventilation system for plugging.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 8
81. Check the injector connections.
2. If any of the injectors are connected to an incorrect
cylinder, correct as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 9
91. Perform the ªInjector Coil/Balance Testº in Fuel
Metering System
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 10
101. Refer to Engine Cooling for cooling system
diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 11
111. Remove excessive carbon buildup with a top engine
cleaner. Refer to the instructions on the top engine
cleaner can.
2. Perform the exhaust emission test.
Does the vehicle pass the test?
ÐSystem OKGo to Step 13
12Perform the exhaust emission test.
Does the vehicle pass the test?
ÐSystem OKGo to Step 13

6E±280
ENGINE DRIVEABILITY AND EMISSIONS
Backfire Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Fuel ignites in the intake manifold, or in the exhaust
system, making a loud popping noise.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to
Visual/Physic
al Check
41. Check for proper ignition voltage coil output with
spark tester 5-8840-0383-0. Refer to
Electric
Ignition System
for procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Remove spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Electronic Ignition
System
.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs. Refer to
DTC P0172 to determine the
cause of a rich condition or
Engine Mechanical for an oil
fouling condition.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
61. Visually/physically inspect the ignition coils for
cracks.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Check for an intermittent ignition system
malfunction:

Intermittent CKP 58X signal.

Intermittent ignition feed circuit or sensor
ground circuit to the crankshaft position
sensor.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Check the fuel pressure. Refer to Fuel System
Pressure Test
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9

6E±283 ENGINE DRIVEABILITY AND EMISSIONS
Cuts Out, Misses Symptom

 
StepNo Ye s Value(s) Action
101. Visually/physically inspect for the following
conditions:

Restricted air intake system. Check for a
possible collapsed air intake duct, restricted
air filter element, or foreign objects blocking
the air intake system.

Throttle body. Check for objects blocking the
IAC passage or throttle bore, excessive
deposits in the IAC passage and on the IAC
pintle, and excessive deposits in the throttle
bore and on the throttle plate.

Large vacuum leak. Check for a condition that
causes a large vacuum leak, such as an
incorrectly installed or faulty PCV valve or
brake booster hose disconnected .
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
11Check the injector connections. If any of the injectors
are connected to an incorrect cylinder, correct as
necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Perform the ªInjector Coil/Balance Testº in Fuel
Metering System
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. Check for fuel in the pressure regulator vacuum
hose.
2. If fuel is present, replace the fuel pressure regulator
assembly. Refer to
Fuel Metering System.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 14
141. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electronic Ignition
System
for the procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 15
151. Remove spark plugs. Check for wet plugs, cracks,
wear, improper gap, burned electrodes, or heavy
deposits. Refer to
Electronic Ignition System.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 16
161. Check for a loose ignition coil ground.
Refer to
Electronic Ignition System.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 17

6E±285 ENGINE DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Momentary lack of response as the accelerator is
pushed down. Can occur at any vehicle speed. Usually
most pronounced when first trying to make the vehicle
move, as from a stop sign. May cause the engine to stall
if severe enough.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to
Visual/Physic
al Check
41. Check the fuel control heated oxygen sensors
(HO2S, B1S1 and B2S1). The fuel control heated
oxygen sensors (HO2S) should respond quickly to
different throttle positions. If they don't, check them
for silicon or other contaminants from fuel or use of
improper RTV sealant. The sensors may have a
white powdery coating.
Silicon contamination causes a high but false
HO2S signal voltage (rich exhaust indication).
The PCM will then reduce the amount of fuel
delivered to the engine, causing a severe
driveability problem. For more information, refer
to
Powertrain Control Module (PCM) and Sensors.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Check the fuel pressure. Refer to Fuel System
Pressure Test.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
6Observe the TP angle display on Tech 2 while slowly
increasing throttle pedal.
Does the TP angle display steadily increase from 0% at
closed throttle to 100% at WOT?
ÐGo to Step 7Go to Step 18
7Monitor the long term fuel trim on Tech 2.
Is the long term fuel trim significantly in the negative
range (rich condition)?
ÐGo to Step 8Go to Step 9
81. Check items that can cause the engine to run rich.
Refer to
Diagnostic Aids in DTC P0172 Diagnostic
Support
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10
91. Check items that can cause the engine to run lean.
Refer to
Diagnostic Aids in DTC P0171 Diagnostic
Support
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10

6E±310
ENGINE DRIVEABILITY AND EMISSIONS
Pedal Stroke Adjustment Procedure
1. Loosen the jam nut and rotate the kick-down switch
counterclockwise.
TS24039
2. Fully depress the pedal and hold it by hand. Rotate
the switch clockwise until the switch clicks.
3. Rotate the switch 1/2 turn further and lock it in this
position by tightening the jam nut.
TS24040
4. Step on the accelerator pedal and make sure there is
a clicking sound at the full-stroke position.
Fuel Filter Cap
General Description
The fuel filler cap includes a vacuum valve and a pressure
valve.If high vacuum or high pressure occurs in the fuel tank,
each valve works to adjust the pressure in order to
prevent damage to the tank at the EGR valve.
TS23767
Inspection Procedure
NOTE: Replace the fuel filler cap with the same type of
filler cap that was originally installed on the vehicle.

Check the seal ring in the filler cap for any abnormality
and for seal condition.

Replace the filler cap if any abnormality is found.
Fuel Filter
Removal Procedure
1. Disconnect the negative battery cable.
2. Remove the fuel filler cap.
041RW005

6E±315 ENGINE DRIVEABILITY AND EMISSIONS
Installation Procedure
1. Install the O-ring backup on the fuel injector.
2. Install the new O-ring on the fuel injector.
3. Install the fuel injector on the fuel rail.
055RW009
4. Use new fuel injector retainer clips to retain the fuel
injector to the fuel rail.
5. Coat the end of the fuel injector with engine oil.
6. Install the fuel rail. Refer to
Fuel Rail.
014RW164
7. Install the upper intake manifold. Refer to Common
Chamber in Engine Mechanical.
8. Install the engine cover.
9. Connect the negative battery cable.
Fuel Pressure Regulator
Removal Procedure
CAUTION: To reduce the risk of fire and personal
injury, it is necessary to relieve the fuel system
pressure before servicing the fuel system
components.
CAUTION: After relieving the system pressure, a
small amount of fuel may be released when servicing
fuel lines or connections. Reduce the chance of
personal injury by covering the fuel line fittings with
a shop towel before disconnecting the fittings. The
towels will absorb any fuel that may leak out. When
the disconnect is completed, place the towel in an
approved container.
NOTE: Compressed air must never be used to test or
clean a fuel pressure regulator, as damage to the fuel
pressure regulator may result.
NOTE: To prevent damage to the fuel pressure regulator,
do not immerse the pressure regulator in solvent.
1. Depressurize the fuel system. Refer to
Fuel Pressure
Relief Procedure
.
2. Disconnect the negative battery cable.
3. Remove the fuel pump relay. Refer to
Fuel Pump
Relay
.
4. Remove the pressure regulator hose from the fuel
pressure regulator.
014RW110

6E±316
ENGINE DRIVEABILITY AND EMISSIONS
5. Remove the two bolts from the protector that secures
the common chamber.
014RW109
6. Remove the fuel pressure regulator attaching screw.
F06RW043
7. Remove the fuel pressure regulator from the fuel rail.
Disassembly Procedure
1. Remove the O-ring from the fuel pressure regulator.
2. Loosen the swivel nut.
3. Remove the fuel return line from the fuel pressure
regulator.
4. Remove the O-ring from the fuel return line.

The O-ring may be left inside the fuel pressure
regulator instead of on the fuel return line.
F06RW043
Assembly Procedure
1. Install a new O-ring on the fuel return line.
2. Install the fuel return line on the fuel pressure
regulator.
NOTE: Do not over-tighten the swivel nut on the fuel
pressure regulator. The fuel pressure regulator can be
damaged and fuel may leak if the swivel nut is
over-tightened.
3. Tighten the swivel nut.
4. Install a new O-ring on the fuel pressure regulator.

6E±317 ENGINE DRIVEABILITY AND EMISSIONS
Installation Procedure
1. Install the fuel pressure regulator attaching screw.
Tighten

Tighten the fuel pressure regulator attaching screw
to 3 N´m (26 lb in.).
F06RW043
2. Install the fuel pressure regulator on the fuel rail.
3. Install the two bolts to the protector that secures the
common chamber.
014RW109
4. Install the pressure regulator hose to the fuel
pressure regulator.
014RW110
5. Install the fuel pump relay. Refer to Fuel Pump Relay.
6. Connect the negative battery cable.
7. Crank the engine until it starts. Cranking the engine
may take longer than usual due to trapped air in the
fuel lines.
Fuel Metering System
Fuel Pressure Relief Procedure
CAUTION: To reduce the risk of fire and personal
injury, it is necessary to relieve the fuel system
pressure before servicing the fuel system
components.
CAUTION: After relieving the system pressure, a
small amount of fuel may be released when servicing
fuel lines or connections. Reduce the chance of
personal injury by covering the fuel line fittings with
a shop towel before you disconnect the fittings. The
towels will absorb any fuel that may leak out. When
the disconnect is completed, place the towel in an
approved container.
1. Remove the fuel cap.