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Code 42: Fuel Pump

NOTE: For component terminal identification, see TERMINAL IDENTIFICATION  . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE 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
    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 fuel pump connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
  4. Ground fuel pump check terminal. With fuel pump connector disconnected, disconnect MFI relay connector. 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.
  5. Disconnect MFI relay connector. Check voltage between chassis ground and MFI relay connector terminal No. 4 (1.8L) or terminal No. 3 (2.0L). 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.
  6. Turn ignition to OFF position. With MFI connector disconnected, disconnect ECM connector. Ground specified ECM connector terminal and check continuity between chassis ground and specified MFI relay connector terminal. See ECM-TO-MFI GROUND CIRCUIT IDENTIFICATION  table. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
    ECM-TO-MFI GROUND CIRCUIT IDENTIFICATION

    Application ECM Terminal No. MFI Terminal No.
    1.8L 56 5
    2.0L 56 7
  7. With ECM connector disconnected and MFI relay connector disconnected, ground fuel pump check terminal. Check resistance between chassis ground and ECM connector terminal No. 109, and between chassis ground and MFI relay connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
  8. With fuel pump connector and MFI relay connector disconnected, ground MFI relay connector terminal No. 1 (1.8L) or terminal No. 2 (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.
  9. With MFI relay connector disconnected, check for continuity between chassis ground and MFI 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 the ENGINE PERFORMANCE Section.
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