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Fuel Pressure

  1. Ensure a sufficient amount of fuel is in fuel tank and battery is charged. Turn ignition off. Connect a jumper wire between terminals +B and FP of DLC. See Fig 1. Turn ignition on. In engine compartment, grasp fuel hose leading from fuel filter.
  2. Fuel pressure should be felt in hose and fuel return noise should be heard. Turn ignition off. If fuel pressure is evident, go to next step. If fuel pressure is not evident, check fusible links, fuses, MPI or SMPI main relay, fuel pump ECU (except ES300), fuel pump, PCM and wiring connections.
  3. Disconnect negative battery cable. Wait at least 90 seconds for air bag back-up power supply to be depleted. Connect fuel pressure gauge to fuel line fitting (banjo bolt) at:
    • Cold start injector (ES300)
    • Rear end of fuel delivery pipe (GS300 and SC300)
    • Rear end of left fuel delivery pipe (LS400 and SC400).
  4. Ensure ignition is off. Reconnect negative battery cable. Connect a jumper wire between terminals +B and FP of DLC. See Fig 1. Turn ignition on, with engine off. Check fuel pressure.
  5. If fuel pressure is 38-44 psi (2.7-3.1 kg/cm2 ), go to next step. If fuel pressure exceeds specification, replace fuel pressure regulator. If fuel pressure is less than specification, check fuel hose and connections, fuel pump, fuel filter, fuel pressure regulator and injectors. See SYSTEM & COMPONENT TESTING article.
  6. Disconnect jumper wire from DLC. Start engine. Disconnect and plug vacuum hose at fuel pressure regulator. With engine idling, check fuel pressure. See FUEL PRESSURE SPECIFICATIONS  table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, check vacuum hose and fuel pressure regulator.
  7. Reconnect vacuum hose to fuel pressure regulator. With engine idling, check fuel pressure. See FUEL PRESSURE SPECIFICATIONS  table. If fuel pressure is not within specification, check vacuum hose and fuel pressure regulator.
  8. If fuel pressure is within specification, turn engine off, noting fuel pressure. If fuel pressure remains greater than 21 psi (1.5 kg/cm2 ) for at least 5 minutes after engine is turned off, fuel pressure is okay. If fuel pressure decreases to less than 21 psi (1.5 kg/cm2 ) within 5 minutes, check fuel pump, fuel pressure regulator and fuel injectors. See the SYSTEM/COMPONENT TESTS article.
FUEL PRESSURE SPECIFICATIONS

Model/ Application At Idle W/Vacuum psi (kg/cm2 ) At Idle W/O Vacuum psi (kg/cm2 )
Except ES300 28-34 (2.0-2.4) 38-44 (2.7-3.1)
ES300 33-37 (2.3-2.6) 38-44 (2.7-3.1)
Fig 1: Identifying Data Link Connector (DLC) Terminals
G93J78187Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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