Page 657 of 1449

MPI -On-vehicle Service13A-125
ON-VEHICLE SERVICE
FUEL PUMP CONNECTOR DISCONNECTION
(HOW TO REDUCE THE FUEL PRESSURE)
When removing the fuel pipe, hose, etc., since fuel pressure
in the fuel pipe line is high, do the following operation so
as to release the fuel pressure in the line and prevent fuel
from running out.
1. Remove the rear seat assembly. (Refer to GROUP 52A.)
2. Remove the protector.
3. Disconnect the fuel pump module connector.
4. After starting the engine and letting it run until it stops
naturally, turn the ignition switch to “LOOK” (OFF) position.
5. Connect the fuel pump module connector.
6. Install the protector and rear seat assembly.
(Refer to GROUP 52A.)
FUEL PUMP OPERATION CHECK
1. Check the operation of the fuel pump by using the MUT-II
to force-drive the fuel pump.
2. If the fuel pump will not operate, check by using the
following procedure, and if it is normal, check the drive
circuit.
(1) Turn the ignition switch to “LOOK” (OFF) position.
(2) Remove the rear seat assembly. (Refer to GROUP
52A.)
(3) Remove the protector.
(4) Disconnect the fuel pump module connector.
(5) When the fuel pump drive connector is attached
directly to the battery, check if the sound of the fuel
pump operation can be heard.
NOTE
As the fuel pump is an in-tank type, the fuel pump
sound is hard to hear, so remove the fuel filler cap
and check from the tank inlet.
(6) Check the fuel pressure by pinching the fuel hose
with the fingertips.
(7) Connect the fuel pump module connector.
(8) Install the protector and rear seat assembly. (Refer
to GROUP 52A.)
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MPI -On-vehicle Service13A-126
THROTTLE BODY (THROTTLE VALVE AREA)
CLEANING
1. Remove the air intake hose from the throttle body.
2. Spray cleaning fluid on a clean cloth.
3. Wipe off the dirt around the throttle valve with the cloth
sprayed with cleaning fluid.
Caution
(1) Do not spray the cleaning fluid directly to the
throttle valve.
(2) Make sure the cleaning fluid does not enter the
motor from the bypass line. Also make sure it
does not enter the sensor through the shaft.
(3) Be careful not to rub off the molybden applied
around the throttle valve shaft.
4. Attach the air intake hose.
5. Adjust the basic idle speed. (Refer to P.13A-127.)
THROTTLE POSITION SENSOR ADJUSTMENT
1. Connect the MUT-IIto the diagnosis connector.
When not using the MUT-II, proceed as follows:
(1) Disconnect the throttle position sensor connector, and
connect the special tool (test harness: MB991536)
between the disconnected connector taking care not
to confuse the terminal to be connected.
(2) Connect digital voltmeter between the terminal No.
2 and the terminal No. 4 of the throttle position sensor
connector.
2. Turn the ignition switch to “ON” position (but do not start
the engine).
3. Check the output voltage of the throttle position sensor.
Standard value: 535 - 735 mV
Throttle valve molybdenum
application section15 mm
15 mm
Equipment side connectorThrottle
position
sensor
Throttle
body
MB991536
Throttle position sensor
Page 659 of 1449

MPI -On-vehicle Service13A-127
4. If not within the standard value, loosen the throttle position
sensor mounting bolts. Then rotate the sensor body to
adjust.
5. Turn the ignition switch to “LOCK” (OFF) position.
6. Remove the MUT-II. If the MUT-IIis not used, remove
the special tool, and then connect the throttle position
sensor connector.
7. If a diagnosis code is displayed, erase the diagnosis code
by using the MUT-IIor disconnect the negative battery
cable from the battery terminal and then leave it for at
least ten seconds. After that, reconnect the battery cable,
and then let the engine run at idle for approximately 10
minutes.
BASIC IDLE SPEED ADJUSTMENT
NOTE
(1) The basic idling speed has been adjusted by the
speed adjusting screw by the manufacturer, and there
should usually be no need for readjustment.
(2) If the adjustment has been changed by mistake, the
idle speed may become too high or the idle speed
may drop too low when loads from components such
as the A/C are placed on the engine. If this occurs,
adjust by the following procedure.
(3) The adjustment, if made, should be made after first
confirming that the spark plugs, the injectors, the idle
speed control servo, the compression pressure, etc.,
are all normal.
1. Before inspection and adjustment, set the vehicle to the
pre-inspection condition.
2. Connect the MUT-IIto the diagnosis connector (16-pin).
NOTE
When the MUT-IIis connected, the diagnosis control
terminal should be earthed.
3. Start the engine and run at idle.
4. Select the item No. 30 of the MUT-IIActuator test.
NOTE
This holds the idle speed control servo at the basic step
to adjust the basic idle speed.
5. Check the basic idle speed.
Standard value: 850±100 r/min
NOTE
(1) The engine speed may be 20 to 100 r/min lower
than indicated above for a new vehicle [driven
approximately 500 km or less], but no adjustment
is necessary.
(2) If the engine stalls or the engine speed is low even
though the vehicle has been driven approximately
500 km or more, it is probable that deposits are
adhered to the throttle valve, so clean it. (Refer to
P.13A-126.)
Page 660 of 1449

MPI -On-vehicle Service13A-128
6. If not within the standard value range, turn the speed
adjusting screw to make the necessary adjustment.
7. Press the MUT-IIclear key, and release the idle speed
control servo from the Actuator test mode.
NOTE
Unless the idle speed control servo is released, the
Actuator test mode will continue 27 minutes.
8. Turn the ignition switch to “LOCK” (OFF) position.
9. Disconnect the MUT-II.
10. Start the engine again and let it run at idle speed for
approximately 10 minutes; check that the idling condition
is normal.
FUEL PRESSURE TEST
1. Release residual pressure from the fuel pipe line to prevent
fuel gush out. (Refer to P.13A-125.)
2. Disconnect the high-pressure fuel hose at the delivery
pipe side.
Caution
Cover the hose connection with rags to prevent splash
of fuel that could be caused by some residual pressure
in the fuel pipe line.
3. Remove the union joint and bolt from the special tool
(adapter hose) and instead attach the special tool (hose
adapter) to the adapter hose.
4. Install the special tool (for measuring the fuel pressure)
that was set up in step 3.
(1) Install the special tool (for measuring the fuel pressure)
between the high-pressure fuel hose and the delivery
pipe.
(2) Install the fuel pressure gauge set (special tool) on
the special tool (for measuring the fuel pressure)
putting the gasket between them.
(3) Connect the lead wire of the fuel pressure gauge
set (special tool) to the power supply (cigarette lighter
socket) and to the MUT-II.
MB991637
Gasket
MD998709
MD998742
High-pressure
fuel hose
Delivery
pipe
Page 661 of 1449

MPI -On-vehicle Service13A-129
(1) Install the fuel pressure gauge on the special tool
(for measuring the fuel pressure) putting a suitable
O-ring or gasket between them.
(2) Install the special tool which was set up in step (1)
between the high-pressure fuel hose and the delivery
pipe.
5. Connect the MUT-IIto the diagnosis connector.
6. Turn the ignition switch to “ON” position. (But do not start
the engine.)
7. Select “Item No. 07” from the MUT-IIActuator test to
drive the fuel pump. Check that there are no fuel leaks
from any parts.
8. Finish the actuator test or turn the ignition switch to “LOCK”
(OFF) position.
9. Start the engine and run at idle.
10. Measure fuel pressure while the engine is running at
idle.
Standard value: Approximately 230 kPa at cerb idle
11. Disconnect the vacuum hose from the fuel pressure
regulator and measure fuel pressure with the hose end
closed by a finger.
Standard value: 289 - 309 kPa at cerb idle
12. Check to see that fuel pressure at idle does not drop
even after the engine has been raced several times.
13. Racing the engine repeatedly, hold the fuel return hose
lightly with fingers to feel that fuel pressure is present
in the return hose.
NOTE
If the fuel flow rate is low, there will be no fuel pressure
in the return hose.Fuel pressure gauge set
O-ring or gasket
MD998709
MD998742
High-pressure
fuel hose
Delivery
pipe
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MPI -On-vehicle Service13A-130
14. If any of fuel pressure measured in steps 10 to 13 is out of
specification, troubleshoot and repair according to the
table below.
SymptomProbable causeRemedy
DFuel pressure too low
DFuelpressuredropsafterracing
Clogged fuel filterReplace fuel filter
DFuelpressuredrops after racing
DNo fuel pressure in fuel return
hose
Fuel leaking to return side due to poor
fuel regulator valve seating or settled
springReplace fuel pressure regulator
Low fuel pump delivery pressureReplace fuel pump
Fuel pressure too highBinding valve in fuel pressure
regulatorReplace fuel pressure regulator
Clogged fuel return hose or pipeClean or replace hose or pipe
Same fuel pressure when vacuum
hose is connected and when
disconnected
Damaged vacuum hose or clogged
nippleReplace vacuum hose or clean nipple
disconnectedFuel pressure control system
malfunctionCheck the fuel pressure control
system
15. Stop the engine and check change of fuel pressure gauge
reading. Normal if the reading does not drop within 2
minutes. If it does, observe the rate of drop and
troubleshoot and repair according to the table below.
SymptomProbable causeRemedy
Fuel pressure drops gradually after
engineisstopped
Leaky injectorReplace injector
engineisstopped
Leaky fuel regulator valve seatReplace fuel pressure regulator
Fuel pressure drops sharply
immediately after engine is stoppedCheck valve in fuel pump is held openReplace fuel pump
16. Release residual pressure from the fuel pipe line.
(Refer to P.13A-125.)
17. Remove the fuel pressure gauge and special tool from
the delivery pipe.
Caution
Cover the hose connection with rags to prevent splash
of fuel that could be caused by some residual pressure
in the fuel pipe line.
18. Replace the O-ring at the end of the fuel high pressure
hose with a new one. Furthermore, apply engine oil to
the new O-ring before replacement.
19. Fit the fuel high pressure hose over the delivery pipe
and tighten the bolt to specified torque.
Tightening torque: 5.0±1.0 N·m
20. Check for any fuel leaks by following the procedure in
step 7.
21. Disconnect the MUT-II.
Page 663 of 1449
MPI -On-vehicle Service13A-131
COMPONENT LOCATION
NameSymbolNameSymbol
A/C relayJFuel pump relay 1, 2Q
A/C switchTFuel pump relay 3H
Air flow sensor (integrated intake air tempera-
ture sensor and barometric pressure sensor)OFuel pump resistorH
Camshaft position sensorNIdle speed control servo (stepper motor)G
Crank angle sensorKIgnition coil (integrated power transister)M
Detonation sensorEInjectorC
Diagnosis connectorSOxygen sensor (front)L
EGR control solenoid valveDOxygen sensor (rear)X
Engine control relayIPower steering fluid pressure switchA
Engine coolant temperature sensorNResistor (for injector)H
Engine warning lamp (check engine lamp)RSecondary air control solenoid valveD
Engine-ECUUThrottle position sensorG
Fan motor relayJVehicle speed sensorF
Fuel pressure control solenoid valveBWaste gate solenoid valveP
ABCDEFGHIJK
LMNOP
QRSTU
Page 664 of 1449

MPI -On-vehicle Service13A-132
ENGINE CONTROL RELAY CONTINUITY CHECK
Tester
connection
terminalBattery voltageNormal state
2-3Not energizedContinuity
1-4Not energizedNo continuity
Energized [Connect terminal No. 2
to battery (+) terminal, and connect
terminal No. 3 to battery ( - )
terminal.]Continuity
FUEL PUMP RELAY 1, 2 CONTINUITY CHECK
Tester
connection
terminalBattery voltageNormal state
1-4Not energizedContinuity
2-3Not energizedNo continuity
Energized [Connect terminal No. 1
to battery (+) terminal, and connect
terminal No. 4 to battery ( - )
terminal.]Continuity
FUEL PUMP RELAY 3 CONTINUITY CHECK
Tester
connection
terminalBattery voltageNormal state
3-4Not energizedContinuity
1-2Not energizedContinuity
Energized [Connect terminal No. 2
to battery (+) terminal, and connect
terminal No. 1 to battery ( - )
terminal.]No continuity
FUEL PUMP RESISTOR CHECK
1. Disconnect the fuel pump resistor connector.
2. Measure the resistance between the terminals.
Standard value: 0.45 - 0.65Ω
3. If the value is deviated from the standard value, replace
the fuel pump resistor.
INTAKE AIR TEMPERATURE SENSOR CHECK
1. Disconnect the air flow sensor connector.
2. Measure resistance between terminal No. 5 and terminal
No. 6.
Standard value:
13 - 17 kΩ(at - 20_C)
5.7 - 6.7 kΩ(at 0_C)
2.3 - 3.0 kΩ(at 20_C)
1.0 - 1.5 kΩ(at 40_C)
0.56 - 0.76 kΩ(at 60_C)
0.30 - 0.42 kΩ(at 80_C)
Equipment
side connectorEngine control
relay
1
32
4
Equipment
side connector Fuel pump
relay 1
Fuel pump
relay 21
32
4
Equipment
side connector
Fuel pump
relay 3 1
32
4
Equipment
side connector
Fuel pump
resistor 12
Air flow sensor
Equipment side connector
123456 7