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Home >> Isuzu >> 1997 >> Oasis LS >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Basic Testing >> Fuel System >> Fuel Pressure >> Pressure Testing
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Pressure Testing

  1. Disconnect negative battery terminal. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE  . Remove 12-mm sealing nut and washer(s) and connect Fuel Pressure Gauge (07406-0040001 ). Reconnect negative battery terminal. Disconnect vacuum hose from fuel pressure regulator and pinch closed. Start engine, and read fuel pressure. If engine will not start, turn ignition on, wait for 2 seconds, turn ignition off, then on again and read fuel pressure.
  2. With engine idling, reconnect vacuum hose to fuel pressure regulator and note fuel pressure. Both gauge readings should be within specification. See REGULATED FUEL PRESSURE  . If fuel pressure is higher than specified, check for pinched or clogged fuel return hose or defective fuel pressure regulator. If fuel pressure is lower than specified, check for clogged fuel filter, defective fuel pressure regulator or fuel line leakage.
  3. Relieve fuel pressure and remove gauge. Reinstall 12-mm sealing nut using new washer(s). Tighten 12-mm sealing nut to 16 ft. lbs. (22 N.m). Start engine and check for leaks.
    REGULATED FUEL PRESSURE AT IDLE

    Application psi (kg/cm2 )
    Vacuum Hose Disconnected & Pinched 38-46 (2.7-3.2)
    Vacuum Hose Connected 30-37 (2.1-2.6)
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