Isuzu 2008MY N Series Workshop Manual page 96

Step
1. Turn OFF the ignition.
2. Remove the rubber fuel hose from the fuel
filter housing (fuel supply pump side). Use a
pan to catch the fuel from the removed fuel
line.
Important: The fuel pressure/ vacuum gauge
connector and the adapter hose must be
cleaned before connecting to the fuel line.
Otherwise, foreign material internal to the
tools line may damage the fuel supply pump.
3. Connect the gauge adapter (5-8840-2844-0/
EN-47667) with fuel pressure/ vacuum gauge
assembly (5-8840-2844-0/ J-44638) in series
with the filter housing and the disconnected
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fuel hose. Ensure the service tool and fuel line
connections are tight.
4. Bleed the fuel system by priming the priming
pump until it becomes firm, then crank over
the engine for a maximum of 5 seconds.
Repeat as necessary until the engine starts.
5. Let the engine run at idle for at least 1 minute.
6. Monitor the fuel pressure/ vacuum gauge
while holding the engine speed higher than
2500 RPM for a minimum of 1 minute.
Does the fuel pressure/ vacuum gauge ever
indicate a larger vacuum than the specified
amount during the test?
1. Fully clamp off a fuel hose as close to the fuel
tank as possible (this will draw vacuum on the
fuel system). You can also disconnect a fuel
line and plug it.
2. Start the engine and turn the idle up control
knob to the highest position. (Full clockwise
direction. The idle speed is increased up to
1600 RPM.)
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3. Monitor the fuel pressure/ vacuum gauge.
Notice: Release the clamp or open the plug
when the gauge is likely to be more than 8
inHg during the test.
Can a vacuum of at least the specified amount
be pulled on the fuel system?
1. Inspect the fuel lines between the fuel supply
pump and fuel tank for being crushed or
kinked.
2. Inspect for a plugged fuel tank vent hose.
3. Inspect inside the fuel tank (if possible) for any
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foreign material that may be getting drawn into
the fuel line pickup causing a blocked
condition.
4. Repair or replace as necessary.
Did you find and correct the condition?
Action
Engine Control System (4HK1)
Value(s) Yes
5 inHg
Go to Step 10
8 inHg
Go to Step 12
—
Go to Step 19
1A-93
No
Go to Step 9
Go to Step 11
Go to Step 14