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Home >> Mitsubishi >> 1997 >> Eclipse Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing - Non-Turbo >> Fuel System >> Fuel Pressure >> Pressure Testing
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Pressure Testing

  1. Relieve fuel pressure. See RELIEVING FUEL PRESSURE  . On models with fuel rail service valve, connect fuel pressure gauge to fuel rail. On models without fuel rail service valve, disconnect high pressure fuel hose at fuel delivery pipe. Remove throttle body bracket (if necessary). Connect fuel pressure gauge with adapter between fuel delivery pipe and high pressure hose. See Fig 1 .
    Fig 1: Installing Fuel Pressure Tester (Typical)
    G95H31028Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  2. Use scan tool to operate fuel pump.
  3. Start engine and allow it to idle. Measure fuel pressure with vacuum hose connected to fuel pressure regulator. Record fuel pressure reading. See REGULATED FUEL PRESSURE  table. Disconnect and plug vacuum hose from fuel pressure regulator. Record fuel pressure reading.
  4. Check for fuel pressure in fuel return hose by gently pinching hose while increasing engine speed. If fuel volume is low, fuel pressure in return hose will not be felt. Increase engine speed to 2500-3000 RPM, 2-3 times. Return engine to idle. Fuel pressure should not drop when engine is returned to idle.
  5. Turn ignition off. Ensure fuel pressure reading does not decrease within 2 minutes. If a decrease is noted, monitor speed of decrease.
  6. If fuel pressure is lower than specification, fuel pressure drops at idle after increasing engine speed to 2500-3000 RPM, or no fuel pressure in fuel return hose can be felt, check for clogged fuel filter, or faulty fuel pressure regulator or fuel pump.
  7. If fuel pressure is greater than specification, check for a faulty fuel pressure regulator or plugged fuel return line. If fuel pressure does not change when vacuum hose to regulator is connected or disconnected, check for a leaking or clogged vacuum hose to fuel pressure regulator or faulty fuel pressure regulator.
  8. If fuel pressure decreases suddenly after engine is stopped, check valve in fuel pump is not seated. Replace fuel pump. If fuel pressure drops slowly, fuel injector is leaking or fuel pressure regulator valve seat is leaking. Check for faulty fuel injector or fuel pressure regulator. Repair as necessary.
  9. When fuel pressure test is complete, repeat fuel pressure release procedure before disconnecting fuel pressure gauge. Install NEW "O" ring at end of high pressure hose. Check for fuel leaks.
    REGULATED FUEL PRESSURE

    Application At Idle w/Vacuum psi (kg/cm2 ) At Idle w/o Vacuum psi (kg/cm2 )
    2.0L Non-Turbo (1) 47-50 (3.3-3.5)
    (1) Information is not available from manufacturer.
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