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Code 42: Fuel Pump

NOTE: For component terminal identification, see TERMINAL IDENTIFICATION  . For wiring diagrams, see WIRING DIAGRAMS article in this section.
  1. Turn ignition switch to ON position. Using a scan tester, actuate fuel pump. Crank engine with fuel pump actuated. Operating noise should be heard. Pinch fuel pump return hose and feel for fuel flow pulsations. If operating noise is not heard or fuel flow is not felt, replace fuel pump. If conditions are as specified, go to next step.
  2. Apply 12 volts to fuel pump check terminal. See Fig 1 . If fuel pump operates, go to step 5. If fuel pump does not operate, go to next step.
    Fig 1: Locating Fuel Pump Check Terminal (Eclipse)
    G93J80282Courtesy of MITSUBISHI MOTOR SALES OF AMERICA
  3. Disconnect fuel pump connector, located at front of fuel tank. Using DVOM, check for continuity between chassis ground and specified fuel pump connector terminal. See FUEL PUMP GROUND CIRCUIT ID  table. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
    FUEL PUMP GROUND CIRCUIT ID

    Application Terminal No.
    All Models 1
  4. Ground fuel pump check terminal. With fuel pump connector disconnected, disconnect MPI relay connector. Check for continuity between chassis ground and specified fuel pump connector terminal. See FUEL PUMP DRIVE CIRCUIT ID  table. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
    FUEL PUMP DRIVE CIRCUIT ID

    Application Terminal No.
    All Models 2
  5. Disconnect MPI relay connector. Check voltage between chassis ground and specified MPI relay connector terminal. See MPI RELAY VOLTAGE SUPPLY TERMINAL ID  table. With ignition switch in OFF position, voltage should be zero. With engine cranking, voltage should be 8.0 volts or more. If voltage is not as specified, repair ignition switch or wiring harness as necessary. If voltage is as specified, go to next step.
    MPI RELAY VOLTAGE SUPPLY TERMINAL ID

    Application Terminal No.
    Eclipse
    1.8L 4
    7
    2.0L 3
    9
    All Other Models 7
  6. Turn ignition to OFF position. With MPI connector disconnected, disconnect ECM connector. Ground specified ECM connector terminal and check continuity between chassis ground and specified MPI relay connector terminal. See ECM TO MPI GROUND CIRCUIT ID  table. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
    ECM TO MPI GROUND CIRCUIT ID

    Application ECM Terminal No. MPI Terminal No.
    Eclipse
    1.8L 56 5
    2.0L 56 7
  7. On Eclipse, go to next step. On Galant, with fuel pump connector and MPI relay connector disconnected, ground fuel pump check terminal. Check for continuity between chassis ground and MPI relay connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to step 9.
  8. With ECM connector disconnected and MPI relay connector disconnected, ground fuel pump check terminal. Check resistance between chassis ground and ECM connector terminal No. 109, and between chassis ground and MPI relay connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
  9. With fuel pump connector and MPI relay connector disconnected, ground MPI relay connector terminal No. 1 (terminal No. 2 on Eclipse 2.0L). Check for continuity between chassis ground and fuel pump connector terminal No. 2. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
  10. On all models, with MPI relay connector disconnected, check for continuity between chassis ground and MPI relay connector terminal No. 6. If continuity does not exist, repair wiring harness as necessary. If continuity exists, condition required to set code is not present at this time. Test is complete. Intermittent problem may exist. See TESTS W/O CODES article in this section.
  11. Reconnect ECM connector and MPI relay connector. While cranking engine, check voltage between chassis ground and MPI connector terminal No. 1. Voltage should be 8 volts or more. Race engine. Voltage should be 12 volts or more. If voltage is not as specified, replace MPI relay. Repeat step 11. If voltage is still not as specified, replace ECM. If voltage is as specified, condition required to set code is not present at this time. Test is complete. Intermittent problem may exist. See TESTS W/O CODES article in this section.
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