Mitsubishi Galant 9G. Manual — part 1220

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-1180

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 324 kPa (95.7 in.Hg) at
curb idle

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

after the engine has been revved several times.

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

specification, troubleshoot and repair according to the table
below.

11.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.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

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 pressure regulator

Low fuel pump delivery pressure

Replace fuel pump

Fuel pressure too high

Binding valve in 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) <3.8L ENGINE>

13B-1181

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

P.13B-1181

.)

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.

13.Remove the fuel pressure gauge, and special tools

MD998709, MD998742 and MB991637 from the fuel rail.

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

with a new one.

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

the bolts to specified torque.

Tightening torque: 5.0

± 1.0 N⋅m (44 ± 8 in-lb)

16.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.

17.Disconnect scan tool MB991958.

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

M1131000900633

Refer to GROUP 13A, On-vehicle Service

− Fuel Pump Relay

Disconnection (How to Reduce Pressurized Fuel Lines)

P.13A-1127

.

FUEL PUMP OPERATION CHECK

M1131002000700

Refer to GROUP 13A, On-vehicle Service

− Fuel Pump Opera-

tion Check

P.13A-1128

.

AKX01460AB

MD998709

FUEL
RAIL

MD998742

HIGH-
PRESSURE
FUEL HOSE

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-1182

MULTIPORT FUEL INJECTION (MFI) RELAY AND
THROTTLE ACTUATOR CONTROL MOTOR
RELAY CONTINUITY CHECK

M1131050000345

Inspect the MFI relay and throttle actuator control motor relay
for continuity in accordance with the chart shown below.

FUEL PUMP RELAY CONTINUITY CHECK

M1131033000342

Inspect the fuel pump relay for continuity in accordance with
the chart shown below.

BATTERY
VOLTAGE

TERMINAL NO.
TO BE
CONNECTED TO
BATTERY

TERMINAL NO.
TO BE
CONDUCTED

Not supplied

−

2

− 3

Supplied

2

− 3

1

− 4

AK100599

1 2
3 4

1 2
3 4

MFI RELAY OR
THROTTLE
ACTUATOR
CONTROL
MOTOR RELAY
SIDE CONNECTOR

MFI RELAY OR THROTTLE
ACTUATOR CONTROL MOTOR
RELAY SIDE CONNECTOR

AC

BATTERY
VOLTAGE

TERMINAL NO.
TO BE
CONNECTED TO
BATTERY

TERMINAL NO.
TO BE
CONDUCTED

Not supplied

−

2

− 3

Supplied

2

− 3

1

− 4

1 2
3

2

3 4

1

4

AK302122

FUEL PUMP RELAY
SIDE CONNECTOR

FUEL PUMP RELAY
SIDE CONNECTOR

AB

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-1183

INTAKE AIR TEMPERATURE SENSOR CHECK

M1131002800557

1. Disconnect the mass airflow sensor connectors.
2. Measure resistance between terminals 1 and 4.

Standard value:

13

− 17 kΩ [at -20°C (-4°F)]

5.3

− 6.7 kΩ [at 0°C (32°F)]

2.3

− 3.0 kΩ [at 20°C (68°F)]

1.0

− 1.5 kΩ [at 40°C (104°F)]

0.56

− 0.76 kΩ [at 60°C (140°F)]

0.30

− 0.45 kΩ [at 80°C (176°F)]

3. If not within specifications, replace the mass airflow sensor.
4. Measure resistance while heating the sensor using a hair

dryer.

Normal condition:

5. If resistance does not decrease as heat increases, replace

the mass airflow sensor.

ENGINE COOLANT TEMPERATURE SENSOR
CHECK

M1131003100528

CAUTION

Be careful not to touch the connector (resin section) with
the tool when removing and installing.
1. Drain engine coolant, then remove the engine coolant

temperature sensor.

2. With the temperature sensing portion of engine coolant

temperature sensor immersed in hot water, check the
resistance.

Standard value:

14

− 17 kΩ [at -20°C (-4°F)]

5.1

− 6.5 kΩ [at 0°C (32°F)]

2.1

− 2.7 kΩ [at 20°C (68°F)]

0.9

− 1.3 kΩ [at 40°C (104°F)]

0.48

− 0.68 kΩ [at 60°C (140°F)]

0.26

− 0.36 kΩ [at 80°C (176°F)]

3. If resistance deviates from the standard value greatly,

replace the sensor.

4. Apply 3M

 AAD part number 8731 or equivalent to threaded

portion.

5. Install the engine coolant temperature sensor and tighten it

to the specified torque.

Tightening torque: 29

± 10 N⋅m (22 ± 7 ft-lb)

TEMPERATURE

RESISTANCE (k

Ω)

Higher

Smaller

1

2

3 4

AK203041

INTAKE AIR TEMPERATURE
SENSOR CONNECTOR

AB

AK203040 AB

INTAKE AIR
TEMPERATURE
SENSOR

MASS AIRFLOW
SENSOR

AKX01622

AKX01623 AB