Isuzu 2000 Trooper Workshop Manual page 985

6E–116
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
2 1. Turn the ignition "OFF."
2. Turn the air conditioning system "OFF."
3. Relieve fuel system pressure and install the fuel
pressure gauge.
4. Turn the ignition "ON."
NOTE: The fuel pump will run for approximately 2
seconds. Use the Tech 2 to command the fuel pump
"ON".
(Refer to the Miscellaneous Test.)
5. Observe the fuel pressure indicated by the fuel
pressure gauge with the fuel pump running.
Is the fuel pressure within the specified limits?
3 NOTE: The fuel pressure will drop when the fuel pump
stops running, then it should stabilize and remain
constant.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant?
4 1. When the
temperature, turn the ignition "ON" to build fuel
pressure and observe the measurement on the
gauge.
2. Start the engine and observe the fuel pressure
gauge.
Did the reading drop by the amount specified after the
engine was started?
5 Is fuel pressure dropping off during acceleration,
cruise, or hard cornering?
6 Visually and physically inspect the following items for a
restriction:
D
The in-pipe fuel filter.
D
The fuel feed line.
Was a restriction found?
7 Remove the fuel tank and visually and physically
inspect the following items:
D
The fuel pump strainer for a restriction.
D
The fuel line for a leak.
D
Verify that the correct fuel pump is in the vehicle.
Was a problem found in any of these areas?
8 Replace the fuel pump.
Is the action complete?
9 1. Disconnect the vacuum hose from the fuel pressure
regulator.
2. With the engine idling, apply 12-14 inches of
vacuum to the fuel pressure regulator.
Does the fuel pressure indicated by the fuel pressure
gauge drop by the amount specified?
Fuel System Diagnosis
Action
vehicle is at normal
Value(s)
—
290-376 kPa
(42-55 psi)
—
operation
21-105 kPa
(3-15 psi)
—
—
—
—
21-105 kPa
(3-15 psi)
Yes No
Go to OBD
System
Check
Go to Step 2
Go to Step 3 Go to Step 17
Go to Step 4 Go to Step 12
Go to Step 5 Go to Step 9
Check for
Go to Step 6
improper fuel
Go to Step 7
Verify repair
Verify repair Go to Step 8
Verify repair —
Go to Step 10 Go to Step 11