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Pressure Testing

  1. Disconnect negative battery cable. Relieve fuel pressure. See RELIEVING FUEL PRESSURE  . Connect Fuel Pressure Gauge (07406-0040001 ) at 6-mm bolt. Reconnect negative battery cable. Start engine, and note fuel pressure. If vehicle will not start, check for spark. If spark is present and no fuel pressure is evident, inspect fuel pump main relay.
  2. Remove connector from fuel pump main relay. See Fig 1 . Using a test light, check for power on Black/Yellow wire at fuel pump relay connector. If power is present, connect a jumper wire between Black/Yellow wire (B+) and Yellow wire (Yellow/Green wire on Civic & Civic Del Sol).
    Fig 1: Locating Fuel Injection Main Relay
    G92B26659Courtesy of AMERICAN HONDA MOTOR CO., INC.
  3. If fuel pump runs, go to step 4). If fuel pump fails to run, see SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE Section. If no voltage is present on Black/Yellow wire, check for open in wire between fuel pump main relay connector and fuse No. 2 on fuse box. Go to step 4) after repairing circuit.
  4. Start engine. Disconnect vacuum hose from pressure regulator, and check for manifold vacuum. If vacuum is not present, check for restriction in vacuum port or hose. Plug vacuum hose and inspect fuel pressure gauge reading. Gauge reading should be within specification. See REGULATED FUEL PRESSURE  table. Pressure should drop slightly when vacuum hose is reconnected.
    REGULATED FUEL PRESSURE (1)

    Application At Idle - psi (kg/cm2 )
    Accord, Civic & Civic Del Sol
    Vacuum Hose Disconnected 40-47 (2.8-3.3)
    Vacuum Hose Connected 30-38 (2.1-2.7)
    Prelude
    2.2L Engine (F22A1)
    Vacuum Hose Disconnected 36-43 (2.5-3.0)
    Vacuum Hose Connected 28-35 (2.0-2.5)
    2.2L Engine (H22A1)
    Vacuum Hose Disconnected 33-40 (2.3-2.8)
    Vacuum Hose Connected 25-32 (1.8-2.3)
    2.3L Engine(H23A1)
    Vacuum Hose Disconnected 36-43 (2.5-3.0)
    Vacuum Hose Connected 28-35 (2.0-2.5)
    (1) Measure regulated fuel pressure with vacuum hose connected and disconnected from pressure regulator.
  5. If pressure is higher than specified, inspect for pinched or clogged fuel return line between fuel rail and fuel tank. If no problem is found in fuel line, replace pressure regulator.
  6. If pressure is less than specified, inspect for plugged fuel filter. If filter is not plugged, lightly pinch fuel return line. If pressure does not increase, replace fuel pump. If pressure increases, replace pressure regulator.
    NOTE: If vehicle starts and runs, fuel pump main relay is okay.
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