Isuzu 2000 Trooper Workshop Manual page 1284

DTC P1171 – Fuel System Lean During Acceleration
Step
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
2 Are any component-related DTCs set?
3 1. Check the vehicle's fuel tank for an adequate
amount of fuel.
2. Add fuel to the vehicle's fuel tank if the tank is almost
empty.
Was fuel added to the vehicle's fuel tank?
4 1. Place the transmission in park.
2. Using a Tech 2, observe HO2S 1 voltage while
running warm engine 75°C-95°C (167°F-203°F) at
1200 RPM.
3. HO2S 1 voltage should vary within the specified
range.
4. Quickly open the throttle halfway for a few seconds.
Did the voltage suddenly rise toward the high end of the
specified range?
5 1. Disconnect the fuel pump relay and crank the
engine to relieve the fuel pressure.
2. Install the fuel pressure gauge.
3. Start the engine and idle at normal operating
temperature.
4. Disconnect the vacuum line going to the fuel
pressure regulator.
With the engine running, is the fuel pressure within the
specified range?
6 Check for restricted fuel lines or restricted in-line filter.
Was a problem found?
7 1. Ignition "OFF."
2. Remove the fuel pump relay and replace it with a
fused jumper which will connect the relay's battery
terminal to the terminal leading to the fuel pump
fuse.
3. While the fuel pump is operating, use pliers to slowly
close the return line (do not exceed the first
specified value).
Using the pliers to restrict the return line, can the fuel
pressure be manipulated to exceed the second
specified value?
8 Check for:
D
Faulty fuel pump
D
Restricted fuel pump strainer (sock)
D
Incorrect fuel pump
D
Incorrect fuel being used
D
Hot fuel
Is the action complete?
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Action Value(s) Yes
— Go to Step 2
Go to
component
— DTC charts
Go to Step 4
—
Go to Fuel
System
Electrical Test
100-900 mV
Go to OBD
280-325 kPa System
(41-46 psi) Check
— Verify repair
414 kPa
(60 psi)
Go to
325 kPa Diagnostic
Aids
(46 psi)
— Verify repair
6E–415
No
Go to OBD
System
Check
Go to Step 3
Go to Step 5
Go to Step 5
Go to Step 6
Go to Step 7
Go to Step 8
—