Isuzu 1999 RODEO Workshop Manual page 1638

f DTC P1171 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
Diagnostic Aids
f A restricted fuel filter or fuel line, restricted in-tank filter,
or a defective fuel pomp may supply adequate
amounts of fuel at idle, but may not be able to supply
enough fuel during heavy acceleration.
f Water or alcohol in the fuel may cause low HO2S
voltage during acceleration.
f Check for faulty or plugged fuel injector(s).
f Check for low fuel.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
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?
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS
Action
4. When the engine is idling or at steady cruise, the
HO2S voltage should vary from between
approximately 100 mV to 900 mV. It is possible to
measure a satisfactory fuel pressure at idle even
though the pressure may drop at high flow
requirements. It may be necessary to watch fuel
pressure at high engine load.
5. Wrap a shop towel around the fuel pressure
connector to absorb any small amount of fuel
leakage that may occur when installing gauge.
Ignition "ON," pump pressure should be
280-320kPa.
7. Add Caution: Use correct pliers so damage to fuel
lines will not occur.
Value(s)
Go to Step 2
—
component
— DTC charts
— Go to Step 4
Go to Fuel
Diagnosis
100-900 mV
Go to OBD
280-325 kPa
(41-46 psi)
— Verify repair
6E2–395
Yes No
Go to OBD
System
Check
Go to
Go to Step 3
Go to Step 5
System
Go to Step 5
System
Check
Go to Step 6
Go to Step 7