Mitsubishi Montero (2004+). Manual - part 377

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-995

4. Check that the accelerator pedal arm touches the full-closed 

stopper.

5. Turn the ignition switch to the ON position. (but do not start 

the engine.)

6. Turn the accelerator pedal position sensor until the output 

from accelerator pedal position sensor (main) satisfies the 
standard value.

Standard value: 0.905 

− 1.165 volts

7. Tighten the accelerator pedal position sensor mounting bolts 

to specified torque.

Tightening torque: 3.5 

± 1.0 N⋅m (31 ± 8 in-lb)

8. Install the accelerator pedal complete.

FUEL PRESSURE TEST

M1131001900573

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

• MB991637: Fuel Pressure Gauge Set

• MD998709: Adaptor Hose

• MD998742: Hose Adaptor

1. Release residual pressure from the fuel line to prevent fuel 

spray. (Refer to 

P.13A-998

.)

WARNING

To prevent a fire, cover the hose connection with 
shop towels to prevent splashing of fuel that could be 
caused by some residual pressure in the fuel pipe 
line.

2. Disconnect the fuel high-pressure hose at the fuel rail side.
3. Assemble the fuel pressure measurement tools as follows.

AK302917

ACCELERATOR 

PEDAL POSITION 

SENSOR

ACCELERATOR 
PEDAL ARM

FULL-CLOSED
STOPPER

AB

3.5 ± 1.0 N·m
31 ± 8 in-lb

AK201312AC

FUEL HIGH-
PRESSURE
HOSE

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-996

<When using the fuel pressure gauge>

1. Remove the union joint and bolt from special tool 

MD998709 (adapter hose) and instead attach special tool 
MD998742 (hose adapter) to the adapter hose.

2. Place a suitable O-ring or gasket on the assembled special 

tools MD998709 and MD998742 and install the fuel pres-
sure gauge.

3. Install the assembled fuel pressure measurement tools 

between the fuel rail and fuel high-pressure hose.

<When using special tool MB991637 (fuel pressure gauge 

set)>

1. Remove the union joint and bolt from special tool 

MD998709 (adapter hose) and instead attach special tool 
MD998742 (hose adapter) to the adapter hose.

2. Install special tool MB991637 (fuel pressure gauge set) into 

assembled special tools MD998709 and MD998742 via a 
gasket.

3. Install the assembled fuel pressure measurement tools 

between the fuel rail and fuel high-pressure hose.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
4. Connect scan tool MB991958 to the data link connector.
5. Use Actuator test 07 to drive the fuel pump. Check that there 

is no fuel leaking from any section when the fuel pump is 
operating.

6. Stop the fuel pump.
7. Start the engine and run at idle.
8. Measure fuel pressure while the engine is running at idle.

Standard value: Approximately 270 kPa (38 psi) at 
curb idle

9. Disconnect the vacuum hose (blue stripe) from the fuel 

pressure regulator and measure the fuel pressure with the 
hose end closed with your finger.

Standard value: 330 

− 350 kPa (47 − 50 psi) at curb idle

10.Check to see that fuel pressure at idle does not drop even 

after the engine has been revved several times.

11.Revving the engine repeatedly, hold the fuel return hose 

lightly with your fingers to feel that fuel pressure is present in 
the return hose.
NOTE: If the fuel flow rate is low, there will be no fuel pres-
sure in the return hose.

AKX01457AH

FUEL PRESSURE 
GAUGE

O-RING OR GASKET

MD998709

MD998742

FUEL 
RAIL 

FUEL
HIGH-PRESSURE
HOSE

AKX01458

MB991637

O-RING OR GASKET

MD998709

MD998742

FUEL
RAIL

AI

FUEL
HIGH-PRESSURE
HOSE

AK302970

AB

MB991911

MB991824

MB991827

AK201313AB

NIPPLE

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-997

12.If any of fuel pressure measured in steps 8 to 11 is out of 

specification, troubleshoot and repair according to the table 
below.

13.Stop the engine and observe fuel pressure gauge reading. It 

is normal if the reading does not drop within two minutes. If it 
does, observe the rate of drop and troubleshoot and repair 
according to the table below. Start, then stop the engine.

(1) Squeeze the fuel return line closed to confirm leak-down 

occurs from defective fuel pressure regulator.

(2) Squeeze the fuel supply line closed to confirm leak-down 

occurs from defective fuel pump check valve.

(3) If pressure continues to drop with both fuel lines 

squeezed closed, injector(s) are leaking.

14.Release residual pressure from the fuel pipe line. (Refer to 

P.13A-998

.)

WARNING

Cover the hose connection with shop towels to pre-
vent splash of fuel that could be caused by some 
residual pressure in the fuel pipe line.

15.Remove the fuel pressure gauge, and special tools 

MD998709, MD998742 and MB991637 from the fuel rail.

16.Replace the O-ring at the end of the fuel high-pressure hose 

with a new one.

17.Fit the fuel high-pressure hose into the fuel rail and tighten 

the bolts to specified torque.

Tightening torque: 4.9 

± 1.0 N⋅m (43 ± 8 in-lb)

SYMPTOM

PROBABLE CAUSE

REMEDY

• Fuel pressure too low

• Fuel pressure drops after racing

• No fuel pressure in fuel return 

hose

Clogged fuel filter

Replace fuel filter

Fuel leaking to return side due to 
poor fuel regulator valve seating or 
settled spring

Replace fuel pressure regulator

Low fuel pump delivery pressure

Replace fuel pump

Fuel pressure too high

Binding valve in fuel pressure 
regulator

Replace fuel pressure regulator

Clogged fuel return hose or pipe

Clean or replace hose or pipe

Same fuel pressure when vacuum 
hose is connected and when 
disconnected

Damaged vacuum hose or 
clogged nipple

Replace vacuum hose or clean 
nipple

Defective fuel pressure regulator

Replace fuel pressure regulator

SYMPTOM

PROBABLE CAUSE

REMEDY

Fuel pressure drops gradually 
after engine is stopped

Leaky injector

Replace injector

Leaky fuel regulator valve seat

Replace fuel pressure regulator

Fuel pressure drops sharply 
immediately after engine is 
stopped

Check valve in fuel pump is held 
open

Replace fuel pump

AKX01460AC

FUEL 
RAIL

FUEL HIGH-
PRESSURE
HOSE

MD998742

MD998709

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-998

18.Check for fuel leaks.

(1) Use scan tool MB991502 to operate the fuel pump.
(2) Check the fuel line for leaks and repair as needed.

19.Disconnect scan tool MB991958.

FUEL PUMP CONNECTOR DISCONNECTION 
(HOW TO REDUCE PRESSURIZED FUEL LINES)

M1131000900677

When removing the fuel pipe, hose, etc., release fuel pressure 
to prevent fuel splay.
1. Turn the ignition switch to the "LOCK" (OFF) position.
2. Fold down the second seat.
3. Remove the service hole cover (upper) and packing.
4. Remove the service hole cover (lower) and packing.
5. Disconnect fuel pump module connector.
6. Start the engine and let it run until it stops naturally. Turn the 

ignition switch to the "LOCK" (OFF) position.

7. Connect the fuel pump module connector.

FUEL PUMP OPERATION CHECK

M1131002000744

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

ACX00218 AM