Mitsubishi Colt Ralliart. Manual - part 84

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-290

OPERATION

• The battery voltage is applied to the fuel pump 

relay (1) (terminal No. 1) form the ignition switch 
and is earthed to the vehicle body from the fuel 
pump relay (1) (terminal No. 2).

• The battery voltage is applied to the fuel pump 

relay (1) (terminal No. 3) and to the fuel pump 
relay (2) (terminal No. 3) from the fuel pump relay 
(1) (terminal No. 4).

• The battery voltage is applied to the fuel pump 

relay (2) (terminal No. 1) from the ignition switch. 
The engine-ECU <M/T> or engine-CVT-ECU 
<CVT> (terminal No. 110) makes the power tran-
sistor in the unit be in ON position and makes 
currents go on the fuel pump relay (2) coil, and 
that makes the relay be in ON position.

• When the fuel pump relay (2) is in ON position, 

the battery voltage is supplied to the fuel pump 
(low pressure) from the fuel pump relay (2) (ter-
minal No. 4).

FUNCTION

• When the ignition switch ON signal is input to the 

engine-ECU <M/T> or engine-CVT-ECU <CVT>, 
the engine-ECU <M/T> or engine-CVT-ECU 
<CVT> places the fuel pump relay (2) in the ON 
position. Accordingly, the battery voltage is sup-
plied to the fuel pump.

PROBABLE CAUSES

• Failed fuel pump relay 

• Failed fuel pump

• Open/short/damaged circuit in fuel pump drive 

circuit or loose connector contact

• Failed engine-ECU <M/T> or engine-CVT-ECU 

<CVT>

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-117 fuel pump relay 
(1) connector and B-103 fuel pump relay (2) 
connector

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Repair or replace the connector.

STEP 2. Check fuel pump relay.

• Fuel pump relay, continuity check (Refer to 

P.13A-360

).

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Replace fuel pump relay.

AK402061

3

2

1

4

AC

B-103, B-117
J/B side 
connector

Connector: B-103, B-117
J/B (front side)

B-117

B-103

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-291

STEP 3. Perform resistance measurement at 
B-117 fuel pump relay (1) connector.

• Remove relay, and measure at junction block 

side.

• Resistance between terminal No. 2 and earth.

OK: Continuity (2 

Ω or less)

Q: Is the check result normal? 

YES : 

Go to Step 4 .

NO : 

Check intermediate connector B-130, and 

repair if necessary. If intermediate 
connector is normal, check and repair 
harness between B-117 (terminal No. 2) fuel 
pump relay (1) connector and body earth.

• Check earthing line for open circuit 

and damage.

STEP 4. Perform voltage measurement at B-117 
fuel pump relay (1) connector.

• Remove relay, and measure at junction block 

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 .

AK402062

3

2

1

4

AC

B-117
J/B side
connector

Connector: B-117
J/B (front side)

B-117

AK402062

3

2

1

4

AC

B-117
J/B side
connector

Connector: B-117
J/B (front side)

B-117

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-292

STEP 5. Connector check: B-141 ignition switch 
connector

Q: Is the check result normal? 

YES : 

Check intermediate connector B-129, and 

repair if necessary. If intermediate 
connector is normal, check and repair 
harness between B-117 (terminal No. 1) fuel 
pump relay (1) connector and B-141 
(terminal No. 2) ignition switch connector.

• Check power supply line for open 

circuit and damage.

NO : 

Repair or replace the connector.

STEP 6. Perform voltage measurement at B-117 
fuel pump relay (1) connector.

• Remove relay, and measure at junction block 

side.

• Voltage between terminal No. 3 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Check intermediate connectors B-108, and 

repair if necessary. If intermediate 
connectors are normal, check and repair 
harness between B-117 (terminal No. 3) fuel 
pump relay (1) connector and battery.

• Check power supply line for 

open/short circuit.

AK402054

B-141

AC

Connector: B-141

1

2

3

4

5

6

B-141 Harness
side connector

AK402062

3

2

1

4

AC

B-117
J/B side
connector

Connector: B-117
J/B (front side)

B-117

AK402062

3

2

1

4

AC

B-117
J/B side
connector

Connector: B-117
J/B (front side)

B-117

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-293

STEP 7. Perform resistance measurement at 
B-103 fuel pump relay (2) connector.

• Remove relay, and measure at junction block 

side.

• Ignition switch: ST

• Resistance between terminal No. 2 and earth.

OK: Continuity

Q: Is the check result normal? 

YES : 

Go to Step 11 .

NO : 

Go to Step 8 .

STEP 8. Connector check: A-08 engine-ECU 
connector or engine-CVT-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Repair or replace the connector.

AK402063

3

2

1

4

AC

B-103
J/B side
connector

Connector: B-103
J/B (front side)

B-103

AK402725

77

78

79

80

81

82

83

84

92

93

94

95

96

97

98

99

85

86

87

88

89

90

91

100

101

102

103

104

105

106

115

116

117

118

119

120

121

107

108

109

110

111

112

113

114

130

131

132

133

134

135

136

122

123

124

125

126

127

128

129

72 71

74 73

76 75

R

AG

A-08

Connector: 

A-08

Harness side connector

Battery

Engine-ECU <M/T> or
engine-CVT-ECU <CVT>

Main

Index

Group

TOC