Mitsubishi Lancer Evolution IX. Manual - part 386

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-19

INSPECTION PROCEDURE FOR 
DIAGNOSIS CODES

Code No. P0090: Fuel Pressure Control Solenoid Valve System

AK501799

65

43
50

42
49

41
48
60 61

64

46 47
58 59
67 68

45

56
66

52

51

44

53

62

54

63

57

55

1

2

3

4

1

2

Engine control relay

To engine-ECU

B-12X

Fuel pressure control solenoid valve

1

2

48

Engine-ECU

Fuel pressure control solenoid valve circuit

W-B

R-Y

Battery

Wire colour code
B: Black  LG: Light green  G: Green  L: Blue  W: White  Y: Yellow  SB: Sky blue  BR: Brown  O: Orange  GR: Gray
R: Red  P: Pink  V: Violet  PU: Purple

C-119

(MU803782)

B-28

(MU802722)

B-Y

6 <A-13> (*1) or 
13 <C-31> (*2)

B-Y

B-Y

AB

NOTE

*1: L.H. drive vehicles
*2: R.H. drive vehicles

2 

1

4

3 

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-20

OPERATION

• Power is supplied from the engine control relay 

(terminal No. 4) to the fuel pressure control sole-
noid valve (terminal No. 1).

• The engine-ECU (terminal No. 48) causes the 

power transistor in the unit to be ON to supply 
power to the fuel pressure control solenoid valve 
(terminal No. 2).

FUNCTION

• In response to a signal from the engine-ECU, the 

fuel pressure control solenoid valve switches the 
pressure to be introduced into the fuel pressure 
regulator between the intake manifold negative 
pressure and atmospheric pressure.

TROUBLE JUDGMENT

Check Condition

• Battery voltage is 10 V or more.

Judgment Criterion

• Surge voltage cannot be detected within 1 sec-

onds from the time when the fuel pressure control 
solenoid valve has changed from ON to OFF.

PROBABLE CAUSES

• Failed fuel pressure control solenoid valve

• Open/short circuit in fuel pressure control sole-

noid valve circuit or loose connector contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-II/III actuator test

• Item No. 09: Fuel pressure control solenoid valve

OK: Operating sound can be heard and the 
valve vibrates.

Q: Is the check result normal?

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points) 

P.00-5

.

NO : 

Go to Step 2 .

STEP 2. Connector check: B-28 fuel pressure 
control solenoid valve connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace the connector.

STEP 3. Perform resistance measurement at B-28 
fuel pressure control solenoid valve connector.

• Disconnect connector, and measure at solenoid 

valve side.

• Resistance between terminal No. 1 and No. 2.

OK: 28 

− 36 Ω (at 20°C)

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Replace the fuel pressure control solenoid 
valve.

AK305002

1

2

AB

Connector : B-28

Harness side 
connector

B-28(B)

AK305002

1

2

AB

Connector : B-28

Harness side 
connector

B-28(B)

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-21

STEP 4. Perform voltage measurement at B-28 
fuel pressure control solenoid valve connector.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: "ON"

• Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Go to Step 5 .

STEP 5. Connector check: B-12X engine control 
relay connector

Q: Is the check result normal?

YES : 

Check and repair harness between B-28 

(terminal No. 1) fuel pressure control 
solenoid valve connector and B-12X 
(terminal No. 4) engine control relay 
connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace the connector.

STEP 6. Perform voltage measurement at C-119 
engine-ECU connector.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: "ON"

• Voltage between terminal No. 48 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 8 .

NO : 

Go to Step 7 .

AK305002

1

2

AB

Connector : B-28

Harness side 
connector

B-28(B)

AK305003

2

1

3

4

AB

Connector : B-12X

B-12X

Harness side 
connector

Relay box’s
triangle marks

AK305002

1

2

AB

Connector : B-28

Harness side 
connector

B-28(B)

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-22

STEP 7. Connector check: C-119 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Check and repair harness between B-28 

(terminal No. 2) fuel pressure control 
solenoid valve connector and C-119 
(terminal No. 48) engine-ECU connector.

• Check output line for open/short 

circuit.

NO : 

Repair or replace the connector.

STEP 8. Connector check: C-119 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Repair or replace the connector.

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305002

1

2

AB

Connector : B-28

Harness side 
connector

B-28(B)

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>