Mitsubishi 380. Manual - part 642

ON-VEHICLE SERVICE

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-660

ON-VEHICLE SERVICE

COMPONENT LOCATION 

• Refer to component locations GROUP

70

THROTTLE BODY (THROTTLE VALVE AREA) 
CLEANING

M1131001000503

WARNING

If the  air intake duct is removed from the throttle 
body take great care to keep fingers away from the 
throttle plate. The drive motor has very high torque 
and is capable of random movement at any time. Do 
not under any circumstance activate the throttle plate 
by hand.
When removing the throttle body from the intake 
manifold disconnect the wiring first.During replace-
ment connect the wiring last.
Do not activate the throttle body using a DC supply to 
test the motor, as permanent damage to the throttle 
body will result.

1. Remove the throttle body.

CAUTION

• Do not spray the cleaning solvent directly to the throttle 

valve.

• Make sure the cleaning solvent does not enter the 

motor and the sensor through the shaft.

2. Spray cleaning solvent on a clean cloth.

3. Wipe off the dirt around the throttle valve with the cloth 

sprayed with cleaning solvent.

4. Attach the throttle body.

ON-VEHICLE SERVICE

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-661

FUEL PRESSURE TEST

M1131001900584

Required Special Tools:

• Diagnostic tool(MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

• MB991637: Fuel Pressure Gauge Set
•

TBA: Adaptor Hose

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

spray. (Refer to 

P.13A-663

.)

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. Disconnect the fuel high pressure hose at the fuel pipe side 

by unclipping and rotating up the stopper then releasing the 
quick release fitting. Remove the high pressure hose from 
vehicle.

<When using the fuel pressure gauge>

1. Use a suitable 1/4" BSP adaptor between fuel hose and 

Gauge. Attach the gauge and fitting to the adaptor hose.

2. Install the assembled fuel pressure measurement tools to 

the vehicle between the fuel rail and fuel pipe. For correct 
hose fittment Refer to Fuel Hose Installation 

P.13A-673

03DB145A

FUEL 

HIGH-PRESSURE 

HOSE 

03DB254A

FUEL

HIGH-PRESSURE

HOSE

FUEL PIPE

STOPPER

03DB255A

FUEL

HIGH-PRESSURE

ADAPTOR HOSE

FUEL PRESSURE 

GAUGE

O-RING OR GASKET

1/4” BSP ADAPTOR

FUEL 

RAIL 

ON-VEHICLE SERVICE

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-662

<When using special tool MB991637 (fuel pressure gauge 

set)>

1. Use a suitable 1/4" BSP adaptor between fuel hose and 

special tool MB991637. Attach the special tool and fitting to 
the adaptor hose.

2. Install the assembled fuel pressure measurement tools to 

the vehicle between the fuel rail and fuel pipe. For correct 
hose fittment Refer to Fuel Hose Installation 

P.13A-673

4. Turn the Ignition to "ON" listen for fuel pump actuation ( 

Approx. 2 seconds). Check that there is no fuel leaking from 
any section when the fuel pump is operating.

NOTE: As the fuel pump is an in-tank type, the fuel pump 
sound is hard to hear. Remove the fuel tank filler tube cap 
and check from the tank inlet.

5. Start the engine and run at idle.

6. Measure fuel pressure while the engine is running at idle.

Standard value: Approximately 324 kPa (95.7 in.Hg) at 
curb idle

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

after the engine has been revved several times.

8. If any of fuel pressure measured in steps 8 to 9 is out of 

specification, troubleshoot and repair according to the table 
below.

9. 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 supply line closed to confirm leak-down 

occurs from defective fuel pump check valve.

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

squeezed closed, injector(s) are leaking.

03DB256A

FUEL

HIGH-PRESSURE

ADAPTOR HOSE

O-RING OR GASKET

1/4” BSP ADAPTOR

FUEL 

RAIL 

MB991637

SYMPTOM

PROBABLE CAUSE

REMEDY

• Fuel pressure too low

• Fuel pressure drops after racing

Clogged fuel filter

Replace fuel filter

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

Replace fuel pump

Low fuel pump delivery pressure

Replace fuel pump

Fuel pressure too high

Binding valve in fuel pressure 
regulator

Replace fuel pump

ON-VEHICLE SERVICE

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-663

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

P.13A-663

.)

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.

11.Remove the fuel pressure gauge, and special tools from the 

fuel rail.

12.Insert fuel hose quick connector onto fuel rail pipe, taking 

care not to damage or dislodge O-ring. Push connector onto 
pipe firmly and depress clip to attach. Check that connector 
does not dislodge when pulled firmly. 

13.Check for fuel leaks.

(1) Turnthe ignition to "ON" to operate the fuel pump.
(2) Check the fuel line for leaks and repair as needed.

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

M1131000900622

WARNING

When removing the fuel pipe, etc., release fuel pres-
sure to prevent fuel spray.

1. Remove the rear seat cushion assembly (Refer to GROUP 

52A, Rear Seat 

P.52A-55

).

2. Remove the hole cover (LHS).

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

03DB150A

HOLE COVER