1992 Lexus ES 300 fuel pressure testing

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Jumper Installation

CHECK FUEL PUMP OPERATION

Using a suitable jumper wire, connect terminals +B and FP of the data link connector 1.
Turn the ignition switch ON.
NOTICE: Do not start the engine.

Checking Fuel Pump Operation

Check that there is pressure in the hose from the fuel filter.

HINT: At this time, you will hear fuel return noise.

CHECK FUEL PRESSURE
Check that the battery voltage is above 12 volts.
Disconnect the cable from the negative (-) terminal of the battery.

CAUTION: With Airbag work must be started after approx. 30 seconds or longer from the time the ignition switch is turned to the LOCK position and the negative (-) terminal cable is disconnected from the battery.

Cold Start Valve Line
Disconnect the cold start injector connector.
Put a suitable container or shop towel under the cold start injector pipe (No.2 fuel pipe).
Remove the union bolt and two gaskets, and disconnect the cold start injector pipe from the cold start injector.
HINT: Slowly loosen the union bolt.

Connecting Pressure Gauge

Install pressure gauge to the cold start injector with three new gaskets and the union bolt.
Torque: 15 Nm (150 kgf.cm. 11 ft.lbs)

Wipe off any splattered gasoline.
Remove jumper wire.
Turn the ignition switch OFF.
If there is no pressure. check the following parts:
Fusible link
Fuses (AM2 30A, EFI 15A, IGN 7.5A)
SFI main relay
Fuel pump
ECM
Wiring connections
Using a suitable jumper wire, connect terminals +B and FP of the data link connector 1.
Reconnect the battery negative (-) cable.
Turn the ignition switch ON.
Measure the fuel pressure.
Fuel pressure: 265-304 kPa (2.7-3.1 kgf/cm2, 38-44 psi)

If pressure is high, replace the fuel pressure regulator.
If pressure is low, check the following parts:
Fuel hoses and connection
Fuel pump
Fuel filter
Fuel pressure regulator
Injector
Remove jumper wire.
Start the engine.

Fuel Pressure Test - No Vacuum To Regulator

Disconnect the vacuum sensing hose from the fuel pressure regulator, and plug the hose end.
Measure the fuel pressure at idle.
Fuel pressure: 265-304 kPa (2.7-3.1 kgf/cm2, 38-44 psi)

Fuel Pressure Test - Vacuum To Regulator

Reconnect the vacuum sensing hose to the fuel pressure regulator.
Measure the fuel pressure at idle.
Fuel pressure: 226-265 kPa (2.3-2.6 kgf/cm2. 33-37 psi)

If pressure is not as specified, check the vacuum sensing hose and fuel pressure regulator.
Stop the engine. Check that the fuel pressure remains 147 kPa (1.5 kgf/cm2, 21 psi) or more for 5 minutes after the engine is turned off.
If pressure is not as specified, check the fuel pump, pressure regulator and/or injector.
After checking fuel pressure, disconnect the battery negative (-) cable and carefully remove the pressure gauge to prevent gasoline from splashing.
Connect the cold start injector pipe (No.2 fuel pipe) with two new gaskets and the union bolt.
Torque: 15 N-m (150 kgf.cm, 11 ft.lbs)

Reconnect the cold start injector connector.
Reconnect the cable to the negative (-) terminal of the battery.
Check for fuel leakage.