1991 MITSUBISHI 3000GT check engine

FUEL SYSTEM - On-vehicle lnwection of MPI ComDonents13-131
iVARIABLE INDUCTION CONTROL SERVO (DC MOTOR) Variable induction control servo
Y(DC motor)(with built-in induction/-control valve oosition sensor)-7Fllfl807Engine control unit
Close
connector
,\ IOpen@ Equipmentside1,,I2DC motorVariable
induction
control
servo
1 FU0646
Engine control unit connector
7FUO653
OPERATION
lAs the DC motor is driven clockwise or counterclockwise by the signal from the engine control unit, the
variable induction valve opens or closes.
lThe DC motor is driven clockwise or counterclockwise as the direction of current flow is changed by the
motor drive
IC in the engine control unit.
INSPECTIONUsing Multi-use tester
Function
Actuator testItem No.Drive content
Check conditionNormal state
11Drive the variable induc-Ignition switch: ONTurn the variable inductiontion control (MC) servovalve shaft (Variable induc-
(Open and close the
vari-tion valve: FULL CLOSEable induction valve)+ FULL OPEN
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13-132
IFUEL SYSTEM
- 0
n-vehicle Inspection of MPI Components
HARNESS INSPECTION
Engine control unitharness side connectorCheck for an open-circuit or a short-circuit to ground, between the enginecontrol unit and the variable inductioncontrol servo connector.l
Variable induction control servoconnector: DisconnectedlEngine control unit connector:Disconnected
t
Repair the
harness.
*A7FUO84
ACTUATOR INSPECTIONRefer to GROUP 15.
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13-134FUEL SYSTEM - On-vehicle InsDection of MPI ComDonents
INSPECTIONUsing Multi-use Tester
FunctionItem No. Data displayCheck condition. Driving conditionStandard valueData reading 45
Stepper
Engine warmed up
Apply fairly sharp
To reach tempo-motor stepbraking at 50 km/h
rarily 70 to
(4th speed) to100 stepsstop vehicle
NOTESelect a place where a rear-end collision is unlikely.
HARNESS INSPECTION
side connector
Engine control umtharness side connecm
6FU1543
Check for an open-circuit or a short-circuit to ground, between the ABScontrol unit and the engine controlunit.l
ABS control unit connector: Dis-connectedlEngine control unit connector:
Disconnected7Repair the
harness.
(@m-ml)
I
I
I
I
IiI
I
~,
I\
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13-136FUEL SYSTEM - On-vehicle Inspection of MPI Components
HARNESS INSPECTION
’ IEngine control
unit harness
&;;;;;g;;gconnector
.j/ \%: c.
T
Check for an open-circuit, or a short-circuit to ground between the transax-’le control unit and the engine controlunit,
lTransaxle control unit connector:
Disconnected
lEngine control unit connector:
Disconnected
c----JOK
Repair the
harness.
C@pJ- 11161)
*6FU1543Engine control
unit harness
control
?ss side
6FU1543
-I3@ Transaxle control
unit harness sideEngine control
unit harness
side connector
6FU1543
Check for an open-circuit, or a short-circuit to ground between the transax-le control unit and the engine control-unit.
lTransaxle control unit connector:
Disconnected
lEngine control unit connector:
DisconnectedRepair the
harness.
@pJ-gj,
Check for an open-circuit, or a short-circuit to ground between the transax-
le control unit and the engine control
unit.
lTransaxle control unit connector:
Disconnected
lEngine control unit connector:
DisconnectedRepair the-+ harness.
@ml -FJ)
1 TSB Revision

FUEL SYSTEM - Orwehicle lnwection of MPI Components.13-137Fuel gauge cover
03FOOO4
j check terminal ----T( 04~oo1,/RELEASE OF RESIDUAL PRESSURE FROM HIGH
PRESSURE FUEL HOSEM13FGAIMake the following operations to release the pressure remain-
ing in fuel pipe line so that fuel will not flow out.
(I) Remove the fuel gauge cover in the luggage compartment.
(2) Disconnect the fuel pump harness connector.
(3) Start the engine and after it stops by itself, turn the ignition
switch to OFF.
(4) Connect the fuel pump harness connector.
(5) Apply the specified sealant to the rear floor pan.
Specified sealant: 3M ATD Part No. 8509 or equivalent
(6) Install the fuel gauge cover.
FUEL PUMP OPERATION CHECK
M13FDAI
(1) Set the ignition switch at OFF.
(2) Check that when the battery voltage is directly applied to
the fuel pump check terminal (black), the operating sound
of the pump can be heard.
NOTESince the fuel pump is installed in the fuel
.tank, its
operating sound cannot be readily heard. Remove the fuel
tank cap and listen to the operating sound through the filter
port.
(3) Hold the high pressure fuel hose between your fingers and
check that the fuel pressure can be felt.
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13438FUEL SYSTEM - On-vehicle Inspection of MPI ComponentsI/
FUEL PRESSURE TESTMlJFNAT(1) Reduce the internal pressure of the fuel pipes and hoses.
(2) Disconnect the fuel high pressure hose at the delivery pipe
side.
dl
Caution
Cover the hose connection with rags to prevent splash
of fuel that could be caused by some residual pressurein the fuel pipe line.
(3) Set a fuel pressure gauge on the special tool, placing an
adequate O-ring or gasket between the gauge end special
tool prevent fuel leaks.
(4) Attach the special tool set in step (3) to the delivery pipe
between high pressure hose.
(5) Connect the 0 battery terminal.
(6) Connect a jumper wire to the terminal for activation of the
fuel pump and to the positive
0 terminal of the battery to
activate the fuel pump. With fuel pressure applied, check to
be sure that there is no fuel leakage from the fuel pressure
gauge and the special tool connection part.
(7) Disconnect the jumper wire (from the terminal for activation
’of the fuel pump) to stop the fuel pump.
(8) Start the engine and let it idle.
d(9) Measure the fuel pressure during idling.
Standard value:
Approx. 270 kPa (38 psi) at curb idle
Approx. 235 kPa (34 psi) at curb idle
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FUEL SYSTEM - On-vehicle Inspection of Mql Components13439(10)Disconnect the vacuum hose from the fuel pressure
regulator, and then measure the fuel pressure while using a
finger to plug the end of the hose.
Standard value:
330
- 350 kPa (47 - 50 psi) at curb idle
295 - 315 kPa (43 - 45 psi) at curb idle(11
)Check to be sure that the fuel pressure during idling does
not decrease even after the engine is raced a few times.
(12)Use a finger to gently press the fuel return hose while
repeatedly racing the engine, and check to be sure that
there is fuel pressure in the return hose also.
NOTEThere will be no fuel pressure in the return hose if there is
insufficient fuel flow.
(13)lf the fuel pressure measured in steps (9) to (12) deviates
from the standard value range, check for the probable
cause by referring to the table below, and. then make the
appropriate repair.
IConditionProbable cause1 RemedyI
l Fuel pressure is too low.l Fuel pressure drops duringracing.l No fuel pressure in fuel returnhose.
Malfunction of the valve seat withinthe fuel pressure regulator, or fuel
leakage to return, side caused byReplace the fuel filter.
Replace the fuel pressure regulator.
Fuel pump low discharge pressure.Replace the fuel pump.
Fuel pressure is too high.
The valve within the fuel pressureregulator is sticking.Replace the fuel pressure regulator.
Clogging of the fuel return hose and/Clean or replace the hose
and/oror the pipe.pipe.
No change of the fuel pressureDamaged vacuum hose or nippleReplace the vacuum hose, or clean
when the vacuum hose is connected clogging.the nipple.
and when not connected.
Malfunction of the fuel pressure controlChecking the fuel pressure controlsystem system
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13-140FUEL SYSTEM - On-vehicle Inspection of MPI Components
(14)Stop the engine and check for a change of the value
indicated by the fuel pressure gauge. The condition is
normal if there is no decrease of the indicated value within~
two minutes.
,If there is a decrease of the indicated value, monitor the
:d ’speed of the decrease, and, referring to the table below,
determine the cause of the problem and make the
appropriate repair.
Condition
After the engine is stopped, thefuel pressure drops gradually.Probable cause
Injector leakage.
Leakage at the fuel pressure
regulator valve seat.Remedy
Replace the injector.
Replace the fuel pressure regulator.
There is a sudden sharp drop of
the fuel pressure immediately
after the engine is stopped.The check valve (within the fuelpump) is not closed.Replace the fuel pump.
(15)Remove all remaining pressure from inside the fuel pipe.(16)Disconnect the fuel pressure gauge and the special tool
from the delivery pipe.
CautionBecause there will be.a slight amount of remaining
pressure in the fuel pipe line, use rags to cover so thatfuel doesn’t splatter.
(17)Replace the O-ring at the end of the fuel high-pressure hose
with a new one.(I 8)After connecting the fuel high-pressure hose to the delivery
pipe, tighten the installation bolt at the specified torque.
dTightening torque: 5.0 Nm (3.6 ftlbs.)
(19)Check to be sure that there is no fuel leakage.@ Apply battery voltage to the terminal for activation of
the fuel pump so as to activate the fuel pump.@ With fuel pressure applied, check for leakage of the fuel
line.
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