Isuzu Trooper (1998-2002 year). Manual - part 436

 

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Isuzu Trooper (1998-2002 year). Manual - part 436

 

 

6E–114

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Fuel System Diagnosis

  (Cont'd)

Step

No

Yes

Value(s)

Action

8

Replace the fuel pump.

Is the action complete?

—

Verify repair

—

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?

21-105 kPa

(3-15 psi)

Go to 

Step 10

Go to 

Step 11

10

Locate and repair the loss of vacuum to the fuel
pressure regulator.

Is the action complete?

—

Verify repair

—

11

Replace the fuel pressure regulator.

Is the action complete?

—

Verify repair

—

12

1. Run the fuel pump with the Tech 2.
2. After pressure has built up, turn off the pump and

clamp the supply hose shut with suitable locking
pliers which will not damage the hose.

Does the fuel pressure indicated by the fuel pressure
gauge remain constant?

—

Go to 

Step 13

Go to 

Step 15

13

Visually inspect the fuel supply line and repair any
leaks.

Was a problem found?

—

Verify repair

Go to 

Step 14

14

Remove the fuel tank and inspect for leaky hose or
in-tank fuel line.

Was a problem found?

—

Verify repair

Go to 

Step 8

15

1. If the pliers are still clamped to the fuel supply hose,

remove the locking pliers.

2. With suitable locking pliers, which will not damage

the hose, clamp the fuel return line to prevent fuel
from returning to the fuel tank.

3. Run the fuel pump with the Tech 2.
4. After pressure has built up, remove power to the

pump.

Does the fuel pressure indicated by the fuel pressure
gauge remain constant?

—

Go to 

Step 11

Go to 

Step 16

16

Locate and replace any leaking fuel injector(s).

Is the action complete?

—

Verify repair

—

17

Is the fuel pressure indicated by the fuel pressure
gauge above the specified limit?

376 kPa

(55 psi)

Go to 

Step 18

Go to 

Step 21

6E–115

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Fuel System Diagnosis

  (Cont'd)

Step

No

Yes

Value(s)

Action

18

1. Relieve the fuel pressure.  Refer to the 

Fuel

Pressure Relief.

2. Disconnect the fuel return line from the fuel rail.
3. Attach a length of flexible hose to the fuel rail return

outlet passage.

4. Place the open end of the flexible hose into an

approved gasoline container.

5. Run the fuel pump with the Tech 2.
6. Observe the fuel pressure indicated by the fuel

pressure gauge with the fuel pump running.

Is the fuel pressure within the specified limits?

290-376 kPa

(42-55 psi)

Go to 

Step 19

Go to 

Step 20

19

Locate and correct the restriction in the fuel return line.

Is the action complete?

—

Verify repair

—

20

Visually and physically inspect the fuel rail outlet
passages for a restriction.

Was a restriction found?

—

Verify repair

Go to 

Step 11

21

Is the fuel pressure indicated by the fuel pressure
gauge above the specified value?

0 kPa (0 psi)

Go to 

Step 22

Go to 

Step 23

22

1. Command the fuel pump “ON” with the Tech 2.
2. Using suitable pliers which will not damage the fuel

hose, gradually apply pressure with the pliers to
pinch the flexible fuel return hose closed.

CAUTION: Do not let the fuel pressure exceed
the second specified value.

Does the fuel pressure indicated by the fuel pressure
gauge rise above the first specified value?

376 kPa

(55 psi)

414 kPa

(60 psi)

Go to 

Step 11

Go to 

Step 7

23

1. Command the fuel pump “ON” with the Tech 2.
2. Remove the fuel filler cap and listen for the sound of

the fuel pump running.

3. Turn the pump off.

Was the fuel pump running?

—

Go to 

Step 7

Go to 

Fuel

System

Electrical Test

Chart

6E–116

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Exhaust Gas Recirculation (EGR) System Check

D06R200075

Circuit Description

A properly operation exhaust gas recirculation (EGR)
system will directly affect the air/fuel requirements of the
engine.  Since the exhaust gas introduced into the air/fuel
mixture is an inert gas (contains very little or no oxygen),
less fuel is required to maintain a correct air/fuel ratio.
Introducing exhaust gas into the combustion chamber
lowers combustion temperatures and reduces the
formation of oxides of nitrogen (NOx) in the exhaust gas.
Lower combustion temperatures also prevent detonation.
If the EGR pintle were to stay closed, the inert exhaust
gas would be replaced with air and the air/fuel mixture
would be leaner.  The powertrain control module (PCM)
would compensate for the lean condition by adding fuel,
resulting in higher long term fuel trim values.

Diagnostic Aids

The EGR valve chart is a check of the EGR system.  An
EGR pintle constantly in the closed position could cause
detonation and high emissions of NOx.  It could also result
in high long term fuel trim values in the open throttle cell,
but not in the closed throttle cell.  An EGR pintle
constantly in the open position would cause a rough idle.
Also, an EGR mounted incorrectly (rotated 180

°

) could

cause rough idle.  Check for the following items:

D

EGR passages – Check for restricted or blocked EGR
passages.

D

Manifold absolute pressure sensor – A manifold
absolute pressure sensor may shift in calibration
enough to affect fuel delivery.  Refer to 

Manifold

Absolute Pressure Output Check.

6E–117

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Exhaust Gas Recirculation (EGR) System Check

 

Step

Action

Value(s)

Yes

No

1

Check the EGR valve for looseness.

Is the EGR valve Loose?

—

Go to 

Step 2

Go to 

Step 3

2

Tighten the EGR valve.

Is the action complete?

—

Verify repair

—

3

1. Place the transmission selector in Park or Neutral.
2. Start the engine and idle until warm.
3. Using a Tech 2, command EGR “50% ON”.

(Refer to the Miscellaneous Test.)

Does the engine idle rough and lose RPMs?

—

EGR system

working

properly.  No

problem

found.

Go to 

Step 4

4

1. Engine “OFF”.
2. Ignition “ON”.
3. Using a test light to ground, check the EGR harness

between the EGR valve and the ignition feed.

Does the test light illuminate?

—

Go to 

Step 6

Go to 

Step 5

5

Repair the EGR harness ignition feed.

Was the problem corrected?

—

Verify repair

Go to 

Step 6

6

1. Remove the EGR valve.
2. Visually and physically inspect the EGR valve

pintle, valve passages and adapter for excessive
deposits, obstructions or any restrictions.

Does the EGR valve have excessive deposits,
obstructions or any restrictions?

—

Go to 

Step 7

Go to 

Step 8

7

Clean or replace EGR system components as
necessary.

Was the problem corrected?

—

Verify repair

Go to 

Step 8

8

1. Ground the EGR valve metal case to battery (–).
2. Using a Tech 2, command EGR “ON” and observe

the EGR valve pintle for movement.

Does the EGR valve pintle move according to
command?

—

Go to 

Step 9

Go to 

DTC

P1406 chart

9

1. Remove the EGR inlet and outlet pipes from the

intake and exhaust manifolds.

2. Visually and physically inspect manifold EGR ports

and EGR inlet and outlet pipes for blockage or
restriction caused by excessive deposits or other
damage.

Do the manifold EGR ports or inlet and outlet pipes
have excessive deposits, obstructions, or any
restrictions?

—

Go to 

Step 10

EGR system

working

properly.  No

problem

found.

10

Clean or replace EGR system components as
necessary.

Is the action complete?

—

Verify repair

—

 

 

 

 

 

 

 

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