fuel cap ISUZU TF SERIES 2004 Repair Manual

6E–214 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1171 FUEL SUPPLY SYSTEM LEAN
DURING POWER ENRICHMENT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The engine control module (ECM) internal circuitry can
identify if the vehicle fuel system is capable of supplying
adequate amounts of fuel during heavy acceleration
(power enrichment). The ECM monitors the voltage of
the ox ygen sensor during power enrichment. When a
power enrichment mode of operation is requested
during “Closed Loop” operation (by heavy acceleration),the ECM will provide more fuel to the engine. Under
these conditions the ECM should detect a “rich”
condition (high ox ygen sensor voltage). If this “rich”
ex haust is not detected at this time, a Diagnostic
Trouble Code P1171 will set. A plugged fuel filter or
restricted fuel line can prevent adequate amounts of fuel
from being supplied during power enrichment mode.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P1171 D Fuel Supply System Lean During
Po wer Enrichment 1. No DTC re lating to MAP senso r, TPS,
EVAP purge, ECT sensor, CKP sensor,
VSS, injecto r contro l circuit and ignitio n
co ntro l circuit.
2. Engine coolant temperature is more than
60 de g. C.
3. Ma ss a ir flo w is below 13.5m/s.
4. O
2 sensor bank 1 output voltage is below
350mV in power enrichment mode. No fail-safe function.

6E–258 ENGINE DRIVEABILITY AND EMISSIONS
EXCESSIVE EXHAUST EMISSIONS OR ODORS SYMPTOM
DEFINITIONS: Vehicle fails an emission test. There is ex cessive “rotten egg” smell. (Ex cessive odors do not
necessarily indicate ex cessive emissions.)
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?—Go to Step 2Go to OBD
System Check
2 1. 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?—Verify repair Go to Step 3
3 Was a visual/physical check performed?
—Go to Step 4Go to Visual /
physical Check.
4 Does the customer continual accelerate On/Off during
cold condition?—System OK Go to Step 5
5 Is the customer using the incorrect fuel type?
—Replace with
unleaded fuel Go to Step 6
6 Check for vacuum leaks (vacuum lines, intake
manifold, throttle body, etc.)
Were any vacuum leaks found?—Go to Step 17Go to Step 7
7 1. Check fuel cap for proper installation.
2. Secure the fuel cap if necessary.
Was a problem found?—Go to Step 17Go to Step 8
8 Check the fuel pressure. Refer to 6E-108 page “Fuel
System Diagnosis” .
Was a problem found?—Go to Step 17Go to Step 9
9 1. Check for faulty, plugged or incorrectly installed
PCV valve.
2. Verify that the PCV system is not plugged.
Was a problem found? —Go to Step 17Go to Step 10
10 Check the injector connectors, if any of the injectors
are connected to an incorrect cylinder, correct as
necessary.
Was a problem found?—Go to Step 17Go to Step 11
11 Perform the
Injector Coil/Balance Test
(Refer to 6E-
98 page).
Was a problem found.—Go to Step 17Go to Step 12
12 Check for a problem with the engine cooling system.
Was a problem found?—Go to Step 17Go to Step 13
13 Check EVAP canister for fuel loading. Refer to
Evaporative Emission Control System.
Was a problem found?—Go to Step 17Go to Step 14
14 Check the EVAP purge solenoid valve operation.
Is the valve operated normally?—Go to Step 17Veri fy repai r &
Go to Step 15
15 Check the ex haust system for a possible restriction:
Damaged or collapsed pipes
Internal catalytic converter failure
Was a problem found?—Verify repair &
Go to Step 16Go to Step 17

6E–270 ENGINE DRIVEABILITY AND EMISSIONS
FUEL PRESSURE RELIEF
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 fuel 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
fitting with a short towel before disconnecting the
fittings. The towel will absorb any fuel that may leak
out. When the disconnect is completed, place the
towel in an approved container.
1. Remove the fuel filler cap.
2. Remove the fuel pump relay from the underhood
relay box .
3. Start the engine and allow it to stall.
4. Crank the engine for about 30 seconds.
5. Disconnect the negative battery cable.
FUEL RAIL ASSEMBLY
Removal Procedure
NOTE:
Use care when removing the fuel rail assembly in
order to prevent damage to the injector al connector
terminal and the injector spray tips.
Fitting should be capped and holes plugged during
servicing to prevent dirt and other contaminants from
entering open lines and passage.
Important: An eight-digit identification number is
stamped on side of the fuel injector. Refer to this
number when you service the fuel rail or when a
replacement part is required.
1. Disconnect 4 injector connectors.
2. Lift side-clip up on the fuel rail.
3. Disconnect fuel pressure regulator hose.
4. Disconnect wiring harness from the bands on the
fuel rail.
5. Remove the intake pipe.
6. Loosen flare nut.
A. Lift up the injectors carefully to separate them
from intake manifold.
B. Lift up the fuel rail with injectors as assembly.
Do not separate the fuel injectors from fuel rail.
C. If an injector become separated from fuel rail,
injector backup O-ring and injector retainer clip
must be replaced.
D. Drain residual fuel from fuel rail into an
approved container.
7. If removal of fuel pressure regulator is necessary,
Refer to Fuel Pressure Regulator Removal
Procedure.