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Mitsubishi Eclipse. Manual - part 641

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-1107

<When using the special tool MB991637 (fuel pressure

gauge set)>

1. Remove the union joint and bolt from special tool

MD998709 (adaptor hose) and instead attach special tool
MD998742 (hose adaptor) to the adaptor 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 the 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 (79.7 in.Hg) at
curb idle

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

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

Standard value: 330

− 350 kPa (97.5 − 103 in.Hg) 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.

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

specification, troubleshoot and repair according to the table
below.

AKX01458

MB991637

O-RING OR GASKET

MD998709

MD998742

HIGH-
PRESSURE
FUEL HOSE

FUEL
RAIL

AK300810

MB991911

16-PIN

MB991827

MB991824

AK000119

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-1108

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.13B-1109

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)

18.Check for fuel leaks.

(1) Use scan tool MB991958 to operate the fuel pump.
(2) Check the fuel line for leaks and repair as needed.

19.Disconnect scan tool MB991958.

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

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-1109

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

M1131000900343

Refer to GROUP 13A, On-vehicle Service

− Fuel Pump Relay

Disconnection (How to Reduce Pressurized Fuel Lines)

P.13A-932

FUEL PUMP OPERATION CHECK

M1131002000379

Refer to GROUP 13A, On-vehicle Service

− Fuel Pump Opera-

tion Check

P.13A-932

MULTIPORT FUEL INJECTION (MFI) RELAY
CONTINUITY CHECK

M1131050000301

Refer to On-vehicle Service

− Multiport Fuel Injection (MFI)

Relay Continuity Check

P.13A-934

FUEL PUMP RELAY CONTINUITY CHECK

M1131033000308

Refer to On-vehicle Service

− Fuel Pump Relay Continuity

Check

P.13A-934

INTAKE AIR TEMPERATURE SENSOR CHECK

M1131002800483

Refer to On-vehicle Service

− Intake Air Temperature Sensor

Check

P.13A-935

ENGINE COOLANT TEMPERATURE SENSOR
CHECK

M1131003100465

Refer to On-vehicle Service

− Engine Coolant Temperature

Sensor Check

P.13A-935

THROTTLE POSITION SENSOR CHECK

M1131003200514

Required Special Tool:

• MB991348: Test Harness Set

Checking the Terminal Resistance
1. Disconnect the throttle position sensor connector.
2. Measure the resistance between throttle position sensor

side connector terminals No. 1 and No. 4.

Standard value: 3.5

− 6.5 kΩ

3. Measure the resistance between throttle position sensor

side connector terminals No. 1 and terminal No. 3.

Normal condition:

4. If the resistance is outside the standard value, or if it doesn't

change smoothly, replace the throttle position sensor.

Throttle valve slowly open
until fully open from the idle
position

Changes smoothly in
proportion to the opening
angle of the throttle valve

AKX01413

THROTTLE POSITION
SENSOR SIDE CONNECTOR

1 2 3 4

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-1110

NOTE: After replacement, the throttle position sensor should
be adjusted. (Refer to

P.13B-1103

Check using oscilloscope
1. Disconnect the throttle position sensor connector and

connect the test harness special tool (MB991348) in
between. (All terminals should be connected.)

2. Connect the oscilloscope probe to the throttle position

sensor side connector terminal No. 3.

3. Turn the ignition switch to the "ON" position.

4. Slowly move the throttle lever from the idle position to the

full-throttle position and check then if the waveform is free
from any noise.

5. If any noise is recognized, replace the throttle position

sensor.
NOTE: After replacement, the throttle position sensor should
be adjusted. (Refer to

P.13B-1103

HEATED OXYGEN SENSOR CHECK

M1131005000635

Required Special Tools:

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

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

• MD998464: Test Harness

• MB991316: Test Harness

• MB991658: Test Harness Set

<Right bank and left bank heated oxygen sensor (front)>
1. Use scan tool MB991958, observe HO

S reading. If values

are unsatisfactory, or if the scan tool is not available, use the
following procedure:

(1) Disconnect the heated oxygen sensor connector and

connect special tool MD998464 to the connector on the
heated oxygen sensor side.

AK102987AB

1 2 3 4

THROTTLE POSITION
SENSOR CONNECTOR

OSCILLOSCOPE

MB991348

AKX01462AB

NORMAL WAVEFORM

THROTTLE LEVER
FULL-THROTTLE
POSITION

THROTTLE
LEVER
IDLE
POSITION

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