Mitsubishi Grandis. Manual - part 783

ON-VEHICLE SERVICE

MULTIPORT FUEL INJECTION (MPI)

13A-383

Examples of Abnormal Wave Patterns

•

Example 1

Cause of problem
Sensor interface malfunction. (Motor is not 

operating)

Wave pattern characteristics
Induced electromotive force from the motor 

turning dose not appear.

•

Example 2

Cause of problem
Open circuit in the line between the EGR valve 

and the engine-ECU <M/T> or 
engine-A/T-ECU <A/T>.

Wave pattern characteristics
Current is not supplied to the motor coil on the 

open circuit side. (Voltage dose not drop to 0 
V.)

Furthermore, the induced electromotive force 

waveform at the normal side is slightly 
different from the normal waveform.

ON-VEHICLE SERVICE

THROTTLE BODY (THROTTLE VALVE 
AREA) CLEANING

M1131001000699

1. Remove the air intake hose from the throttle body.
2. Remove the throttle body assembly.

CAUTION

• Do not spray the cleaning fluid directly to the 

throttle valve.

• Make sure the cleaning fluid does not enter 

the motor from the bypass line. Also make 
sure it does not enter the sensor through the 
shaft.

3. Spray cleaning fluid on a clean cloth.
4. Wipe off the dirt around the throttle valve with the 

cloth sprayed with cleaning fluid.

5. Install the throttle body assembly.
6. Attach the air intake hose.

FUEL PRESSURE TEST

M1131001900830

1. Release residual pressure from the fuel pipe line 

to prevent fuel gush out (Refer to 

P.13A-386

).

CAUTION

Cover the hose connection with rags to prevent 
splash of fuel that could be caused by some 
residual pressure in the fuel pipe line.

2. Disconnect the high-pressure fuel hose at the 

delivery pipe side.

AKX01608AE

AKX01609AF

Open
circuit
side

Normal
side

AK300686AC

ON-VEHICLE SERVICE

MULTIPORT FUEL INJECTION (MPI)

13A-384

3. Assemble the fuel pressure measurement tools 

as follows.

<When using the fuel pressure gauge set (special 

tool)>

a. Remove the union joint and bolt from the special 

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

b. Via a gasket, install the special tool fuel pressure 

gauge set (MB991637 or MB991981) into the 
special tool that has already assembled as 
described in (a) above.

<When using the fuel pressure gauge>

a. Remove the union joint and bolt from special tool 

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

b. Via a suitable O-ring or gasket, install the fuel 

pressure gauge to the special tool that has 
already assembled as described in (a) above.

4. Install the assembled fuel pressure measurement 

tools between the fuel rail and high-pressure fuel 
hose.

CAUTION

To prevent damage to the MUT-III, always turn the 
ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting the MUT-III.
5. Connect the MUT-III to the diagnosis connector.
6. Turn the ignition switch to ON position (But do not 

start the engine).

7. Select "Item No. 07" from the MUT-III actuator test 

to drive the fuel pump. Check that there are no 
fuel leaks from any parts.

8. Finish the actuator test or turn the ignition switch 

to "LOCK" (OFF) position.

9. Start the engine and run at idle.
10.Fuel pressure measurement while the engine is 

running at idle.

Standard value: Approximately 248 kPa at 
cerb idle

11.Disconnect the vacuum hose from the fuel 

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

Standard value: 324 

− 334 kPa at cerb idle

12.Check to see that fuel pressure at idle does not 

drop even after the engine has been raced 
several times.

AKX01458 AG

MB 991637

Gasket

MD 998709

MD 998742

High-pressure
fuel hose

Delivery
pipe

AK305430AB

MB 991981

Gasket

MD 998709

MD 998742

High-pressure
fuel hose

Delivery
pipe

AKX01457AF

MD 998742

MD 998709

O-ring or gasket

Fuel pressure 
gauge set

High-pressure
fuel hose

Delivery
pipe

AK300687

Vacuum hose

AC

ON-VEHICLE SERVICE

MULTIPORT FUEL INJECTION (MPI)

13A-385

13.Racing the engine repeatedly, hold the fuel return 

hose lightly with 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 pressure in the return hose.

14.If any of fuel pressure measured in steps 10 to 13 

is out of specification, troubleshoot and repair 
according to the table below.

15.Stop the engine and check change of fuel 

pressure gauge reading. Normal if the reading 
does not drop within 2 minutes. If it does, observe 
the rate of drop and troubleshoot and repair 
according to the table below.

16.Release residual pressure from the fuel pipe line 

(Refer to 

P.13A-386

).

CAUTION

Cover the hose connection with rags to prevent 
splash of fuel that could be caused by some 
residual pressure in the fuel pipe line.
17.Remove the fuel pressure gauge and special tool 

from the delivery pipe.

18.Replace the O-ring at the end of the fuel high 

pressure hose with a new one. Furthermore, 
apply engine oil to the new O-ring before 
replacement.

19.Fit the fuel high pressure hose over the delivery 

pipe and tighten the bolt to specified toque.

Tightening torque: 5 

± 1 N⋅m

20.Check for any fuel leaks by following the 

procedure in step 7.

21.Disconnect the MUT-III.

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

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

ON-VEHICLE SERVICE

MULTIPORT FUEL INJECTION (MPI)

13A-386

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

M1131000900729

WARNING

When removing the fuel pipe, etc., release 
fuel pressure to prevent fuel spray.

1. Remove the instrument panel fuse box lid <L.H. 

drive vehicles> or instrument panel parcel box 
<R.H. drive vehicles> (Refer to GROUP 52A 

− 

Instrument Panel 

P.52A-2

).

2. Remove the fuel pump relay (2) in the the junction 

block.

3. Crank the engine for at least two seconds.
4. If the engine is not started, turn the ignition switch 

to the "LOCK (OFF)" position.

5. If the engine is started, turn the ignition switch to 

the "LOCK (OFF)" position after the engine 
stopped.

6. Install the fuel pump relay (2).
7. Install the instrument panel fuse box lid <L.H. 

drive vehicles> or instrument panel parcel box 
<R.H. drive vehicles> (Refer to GROUP 52A 

− 

Instrument Panel 

P.52A-2

).

FUEL PUMP OPERATION CHECK

M1131002000829

1. Remove the fuel tank cap.

NOTE: As the fuel pump is an in-tank type, the 
fuel pump sound is hard to hear. Then check the 
sound from the tank inlet.

2. Check the operating of the fuel pump by MUT-III 

to force-drive the fuel pump.

3. If the fuel pump will not operate, check by using 

the following procedure. If normal, check the fuel 
pump drive circuit.
(1) Turn the ignition switch to the "LOCK" (OFF) 

position.

(2) Remove the second seat assembly, the rail 

cover outer and the rail cover inner. (Refer to 
GROUP 52A, Second Seat Assembly 
Removal and Installation 

P.52A-26

).

AC310733AB

<L.H. drive vehicles>

Instrument panel fuse box lid

AC310315AB

<R.H. drive vehicles>

Instrument panel parcel box

AC310734

Fuel pump relay (2)

<L.H. drive vehicles>

AC302306 AD

Fuel pump relay (2)

<R.H. drive vehicles>