1991 MITSUBISHI 3000GT Service Manual

FUEL SYSTEM * On-vehicle Inspection of MPI Components
13-39
- N&Turbo, Turbo> i/
EGR control solenoid valve
A / / / 7FUlOll
/ Ylilr--/ / / / 7FU1007
7FUlOlOTSB Revision

13-40FUEL SYSTEM -On-vehicle Inspection of MPI Components
COMPONENTS INSPECTION PROCEDUREM13YBAC
USING MULTI-USE TESTER
(1) Check by the service data and actuator test function. If any ij
abnormality is found, check the body harness, components,
etc. and repair as necessary.
(2) After repair, check again with the multi-use tester to makesure that the input and output signals are now normal.
(3) Erase the self-diagnosis trouble code in memory.
(4) Disconnect the multi-use tester.
(5) Start the engine and perform running test, etc. to make
sure that the troubles have been corrected.
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FUEL SYSTEM - On-vehicle Inspection of MPI Components13-41
POWER SUPPLY AND IGNITION SWITCH-IG
Engine control
unit
16FO29:
Q-i=++=
iA MPI control relay
ml3Yuu
lcmition switch (IG)
@ Harness sideccmnector
62
I
Engine control unit
Engine control unit connector7FUO950
OPERATIONl
While the ignition switch is on, battery power is supplied to the engine control unit, the injector, the airflow sensor, etc.
lWhen the ignition switch is turned on, the battery voltage is applied from the ignition switch to the engine
control unit, which then turns ON the power transistor to energize the control relay coil. This turns ON thecontrol relay switch and the power is supplied from the battery to the engine control unit through the
control relay switch.
INSPECTION
Using Multi-use Tester
IFunctionItem No.Data displayICheck conditionIStandard valueI
Data reading16Engine control unit
power voltageIgnition switch: ONsv
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IS-42FUEL SYSTEM - On-vehicle Inspection of MPI Components
HARNESS INSPECTION
Measure the ignition switch terminalinput voltage.l
Engine control unit connector:
Disconnectedl Ignition switch: ON
01
orOlLO427Voltage
(V)svRepair the
harness.
(Ignitionswitch -@I
Measure the power supply voltage ofthe control relay.l Connector: Disconnected
Voltage
(V)sv
Repair the
harness.
(Battery -
@IIN
ontrolrelay connector: Discon-
Engine controlunit harnessCheck for an open-circuit, or a short-
side connectorcircuit to ground between the enginecontrol unit and the control relay.l
Control relay connector: Discon-l
Engine control unit connector:
Disconnected
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FUEL SYSTEM - On-vehicle Inspection of MPI Components13-43OlLO521
01 LO220
011022:
CONTROL RELAY INSPECTION
Caution
When applying battery voltage directly, make sure that it is
applied to correct terminal. Otherwise, the relay could be
damaged.
(1) Remove the control relay.
(2) Using jumper wires, connect terminal @ of control relay tobattery
0 terminal and terminal @ of control relay to
battery
0 terminal.
(3) Connecting and disconnecting the jumper wire to battery 0
terminal, measure the voltage across terminals @ and @ ofthe control relay.
(4) Using jumper wires, connect terminal @ of control relay tobattery
0 terminal and terminal @ of control relay to
battery
0 terminal.
(5)Connecting and disconnecting the jumper wire to battery 0
terminal, check the continuity across terminals @ and @ ofthe control relay.
(6) Using jumper wires, connect terminal @ of control relay tobattery
0 terminal and terminal @ of control relay to
battery
0 terminal.
(7) Connecting and disconnecting the jumper wire to battery 0
terminal, measure the voltage at terminal @ of the control
relay.(8) Replace the control relay if any defect is evident.
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13-44FUEL SYSTEM - On-vehicle Inspection of MPI Components
ENGINE CONTROL UNIT POWER GROUNDMlBYD~
wEngine controld/ unii16FO292
Engine control unit
L-7-l d
1326
Yx
01A01@1
Engine control unit connector
7FUO653
OPERATIONGrounds the engine control unit
TROUBLESHOOTING HINTSIf the ground wire of the engine control unit is not connected securely to ground, the unit will not operate
correctly.
HARNESS INSPECTION
unit harness
side connector
Check for continuity of the ground
circuit.l
Engine control unit connector:DisconnectedTSB Revision

FUEL SYSTEM -On-vehicle Inspection of MPI Components13-45
FUEL PUMP
@ Equipment side
connector
@ Harness side
connector
lqnition switch (IG,i
LL--- /A&
\“// //@JFuel pump connector
Engine control unit connectorEquipment
connectorside
@ Harness side
connector
7FUO653
7FUO952
M13YEAA2
OPERATIONl Drives the fuel pump during cranking and engine operation.
lWhen the ignition switch is set to START, current flows from the ignition switch through the control relay
coil to ground. This turns on the control relay switch and drive power is supplied from the battery throughthe control relay switch to the fuel pump.
lWhile the engine is running, the engine control unit keeps the power transistor on and energizes the
icontrol relay coil so that drive power is supplied to the fuel pump.
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13-46FUEL SYSTEM - On-vehicle Inspection of MPI Components
INSPECTIONUsing Multi-use Tester
FunctionItem No.DriveCheck condition
Check contentNormal statedActuator test 07
Fuel pump isl Engine cranking
Hold return hose withPulsation is felt
driven to cir-l Forced drive of fuelculate fuelfingers to feel pulsation
pump
Check is made forindicating fuel flow
above two conditions
Listen to pump operating
sound near fuel tankOperating sound isheard
HARNESS INSPECTION
check terminal
7FUO954
@ Harness side
connector7FUO955
Check the fuel pump.l
Apply battery voltage to thechecking terminal and operate the
w-w
Check for continuity of the ground
circuit.l
Fuel pump connector: Discon-
nected
Repair the
harness.
@FJ-Ground)
Check for continuity between the fuelpump and the checking terminal.l
Fuel pump connector: Discon-
nectedcl4
Repair the
harness.
@vJ-@g)
1 TSB Revision