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Fuel System Pressure Test

NOTE: Before testing fuel pressure, check all fuel delivery and return lines for leaks.
  1. Ensure battery is fully charged. Turn ignition off. Disconnect negative battery cable. Place container or shop towel under cold start injector. Disconnect cold start injector (if equipped). Slowly loosen cold start injector or No. 3 fuel supply pipe union bolt to relieve fuel pressure.
  2. Remove union bolt and gaskets. Install fuel pressure gauge to cold start injector delivery pipe. See Fig 1 off excess fuel.
    Fig 1: Locating Fuel Pressure Gauge Connection (Cressida)
    G91G18263Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 2: Locating Fuel Pressure Gauge Connection (Land Cruiser)
    G91F18262Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 3: Locating Fuel Pressure Gauge Connection (Supra)
    G91J18258Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Install jumper wire between engine check connector FP and +B pins. Refer to the ENGINE CHECK CONNECTOR LOCATION  table. Also, see Figureect negative battery cable, and turn ignition on, with engine off. Measure fuel pressure. Fuel pressure should be same as unregulated pressure. See FUEL PUMP PERFORMANCE  table.
  4. If fuel pressure is high, replace fuel pressure regulator. If fuel pressure is low, check fuel hoses and connections, fuel pump, fuel filter, and fuel pressure regulator
  5. Remove jumper wire installed in step 3). Start engine. Disconnect vacuum sensing hose from fuel pressure regulator, and plug hose end. Fuel pressure regulator is mounted on fuel rail.
  6. Measure unregulated fuel pressure at idle speed. See the FUEL PUMP PERFORMANCE  table. With engine still idling, reconnect fuel pressure regulator vacuum hose.
  7. Measure regulated pressure at idle. If regulated pressure is not as specified, check vacuum sensing hose to fuel pressure regulator. On models so equipped, check fuel pressure-up system. See & I - SYS/COMP TESTS article in this section.
  8. Stop engine. Note fuel pressure. Leave fuel pressure gauge attached to engine for at least 5 minutes. Residual fuel pressure after 5 minutes should be at least 21 psi (1.5 kg/cm2 ).
  9. If pressure is not as specified, check for leaking injectors, faulty fuel pressure regulator or bad check valve in fuel pump. Relieve fuel system pressure. Remove fuel pressure gauge. Install cold start injector. Run engine and check for fuel leaks.
NOTE: For more information on checking fuel injectors and other fuel sub-systems, see I - SYS/COMP TESTS article in this section.
FUEL PUMP PERFORMANCE

Model/ Application Unregulated (1) psi (kg/cm2 ) Regulated (2) psi (kg/cm2 )
Cressida 38-44 (2.7-3.1) 33-37 (2.3-2.6)
Land Cruiser 37-46 (2.6-3.2) 33-37 (2.3-2.6)
Supra
Non-Turbo 38-44 (2.7-3.1) 30-37 (2.1-2.6)
Turbo 33-40 (2.3-2.8) 23-30 (1.6-2.1)
(1) With pressure regulator vacuum hose disconnected and plugged.
(2) With vacuum hose connected to pressure regulator.
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