1991 LEXUS SC400 fuel pressure

ELECTRONIC CONTROL SYSTEM
The control system consists of sensors which detect various engine conditions, and a ECU which deter\
-
mines the injection volume (timing) based on the signals from the sens\
ors.
The various sensors detect the air intake volume, engine rpm, oxygen densit\
y in the exhaust gas, coolant
temperature, air intake temperature and atmospheric pressure etc. and convert the in\
formation into an electrical
signal which is sent to the ECU. Based on these signals, the ECU calculates th\
e optimum ignition timing for the
current conditions and operates the injectors.
The ECU not only controls the fuel injection timing, but also the self diag\
nostic function which records the
occurrence of a malfunction, ignition timing control, idle rpm control, \
EGR control, EVAP control, fuel pressure
control and fuel pump control. FI±9
EFI SYSTEM
± Operation
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PREPARATION
SST (SPECIAL SERVICE TOOLS)
IllustrationPart No.Part NameNote
09268±41045Injection Measuring
Tool Set
(09268±41090)(No. 7 Union)
Injector
(09268±52010)(Injection Measuring
Attachment)
Injector
(09405±09015)(No. 1 Union)
Injector
09268±45012EFI Fuel Pressure
Gauge
09612±24014
Steering Gear
Housing Overhaul
Tool Set
(09617±24011(Steering Rack Wrench)
Fuel pressure pulsation damper
09631±22020
Power Steering
Hose Nut 14 x 17 mm
Wrench SetFuel line flare nut
09816±30010Oil Pressure
Switch Socket
Knock sensor
09842±30070Wire ªFº
EFI Inspection
Injector
09843±18020Diagnosis Check
Wire
09990±01000
Engine Control
Computer Check
Harness ªAº
±
EFI SYSTEM PreparationFI±9
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Preparation
SST (SPECIAL SERVICE TOOLS)
IllustrationPart No.Part NameNote
09268±41045Injection Measuring
Tool Set
(90268±41070)No. 4 Union
Injector
(09268±41080)No. 6 Union
Cold start Injector
(09268±52010)Injection Measuring
Attachment
Injector
09268±45012EFI Fuel Pressure
Gauge
09612±24014
Steering Gear
Housing Overhaul
Tool Set
(09617±24011)Steering Rack Wrench
Fuel pressure pulsation damper
09631±22020
Power Steering
Hose Nut 14 X 17 mm
Wrench SetFuel line flare nut
09816±30010Oil Pressure
Switch SocketKnock sensor
09842±30055Wire ªGº
EFI Inspection
Cold start Injector
09842±30070Wire ªFº
EFI Inspection
Injector
09843±18020Diagnosis Check
Wire
0990±01000
Engine Control
Computer
Check Harness ªAº
FI±10 ± PreparationEFI SYSTEM
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FUEL SYSTEM
1. When disconnecting the high fuel pressure line, a largeamount of gasoline will spill out, so observe the following
procedures:
(a) Remove the luggage compartment trim cover.
(b) Disconnect the fuel pump connector.
(c) Start the engine, After the engine has stopped on itsown, turn off the ignition switch.
(d) Put a container under the connection.
(e) Slowly loosen the connection.
(f) Disconnect the connection.
(g) Plug the connection with a rubber plug.
(h) Reconnect the fuel pump connector.
(i) Reinstall the luggage compartment trim cover.
2. When connecting the flare nut or union bolt on the high pressure pipe union, observe the following procedures:
(Union Bolt Type)
(a) Always use a new gasket.
(b) Tighten the union bolt by hand.
(c) Tighten the union bolt to the specified torque.
Torque: 34 N Vm (350 kgf Vcm, 25 ft Vlbf)
(Flare Nut Type)
(a) Apply a light coat of engine oil to the flare nut and tighten
the flare nut by hand.
(b) Using SST, tighten the flare nut to specified torque.
SST 09631±22020
Torque: 30 N Vm (310 kgf Vcm, 22 ft Vlbf)
HINT: Use a torque wrench with a fulcrum length of 30 cm
(11.81 in.).
3. Observe the following precautions when removing and installing the injectors.
(a) Never reuse the O±ring.
(b) When placing a new O±ring on the injector, take care not
to damage it in any way.
(c) Coat a new O±ring with spindle oil or gasoline before installing±never use engine, gear or brake oil.
FI±14
±
EFI SYSTEM Inspection Precautions
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4. Install the injector to delivery pipe and cylinder head asshown in the illustration.
5. Check that there are no fuel leaks after performing any maintenance on the fuel system.
(a) Using SST, connect terminals +B and FP of the check(ºDIAGNOSISº) connector.
SST 09843±18020
(b) With engine stopped, turn the ignition switch ON.
(c) When the fuel return hose is pinched, the pressure within high pressure line will rise to approx. 392 kPa (4
kgf/cm2, 57 psi). In this state, check to see that there are
no leaks from any part of the fuel system.
NOTICE: Always pinch the hose. Avoid bending as it may
cause the hose to crack.
(d) Turn the ignition switch OFF.
(e) Remove SST from the check connector.
SST 09843±18020
±
EFI SYSTEM Inspection PrecautionsFI±15
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FUEL SYSTEM
1. When disconnecting the high fuel pressure line, a largeamount of gasoline will spill out, so observe the following
procedures:
(a) Put a container under the connection.
(b) Slowly loosen the connection.
(c) Disconnect the connection.
(d) Plug the connection with a rubber plug.
2. When connecting the flare nut or union bolt on the high pressure pipe union, observe the following procedures:
(Union Bolt Type)
(a) Always use a new gasket.
(b) Tighten the union bolt by hand.
(c) Tighten the union bolt to the specified torque.
Torque: 15 N Vm (150 kgf Vcm, 11 ft Vlbf)
(Flare Nut Type)
(a) Apply a light coat of engine oil to the flare nut and tighten
the flare nut by hand.
(b) Using SST, tighten the flare nut to specified torque.
SST 09631±22020
Torque: 30 N Vm (310 kgf Vcm, 22 ft Vlbf)
HINT: Use a torque wrench with a fulcrum length of 30 cm
(11.81 in.).
3. Observe the following precautions when removing and installing the injectors.
(a) Never reuse the O±ring.
(b) When placing a new O±ring on the injector, take care not
to damage it in any way.
(c) Coat a new O±ring with spindle oil or gasoline before installing±never use engine, gear or brake oil.
4. Install the injector to delivery pipe and cylinder head as shown in the illustration. FI±15
EFI SYSTEM
± Inspection Precautions
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5. Check that there are no fuel leaks after performing anymaintenance on the fuel system.
(a) Using SST, connect terminals +B and FP of the check(ºDIAGNOSISº) connector.
SST 09843±18020
(b) With engine stopped, turn the ignition switch ON.
(c) When the fuel return hose is pinched, the pressure within high pressure line will rise to approx. 392 kPa (4
kgf/cm2, 57 psi). In this state, check to see that there are
no leaks from any part of the fuel system.
NOTICE: Always pinch the hose. Avoid bending as it may
cause the hose to crack.
(d) Turn the ignition switch OFF.
(e) Remove the SST from the check connector.
SST 09843±18020
FI±16
EFI SYSTEM
± Inspection Precautions
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FUEL SYSTEM
Fuel Pump
ON±VEHICLE INSPECTION
1. CHECK FUEL PUMP OPERATION(a) Using SST, connect terminals +B and FP of the check
(ºDIAGNOSISº) connector.
SST 09843±18020
(b) Turn the ignition switch ON.
NOTICE: Do not start the engine.
(c) Check that there is pressure in the fuel inlet hose from the fuel filter.
HINT: At this time, you will hear fuel return noise.
(d) Turn the ignition switch OFF.
(e) Remove SST from the check connector.
SST 09843±18020
FI±16
±
EFI SYSTEM Fuel System (Fuel Pump)
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