1999 Chevrolet Cutaway 7.4 JFACTORY OEM SERVICE PROCEDURE

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
  2. If any fuel level sensor or EVAP system DTCs are present, go to applicable DTC. If no fuel level sensor or EVAP system DTCs are present, go to next step.
  3. Inspect EVAP system for the following conditions:
    • Loose, incorrect, defective or missing fuel filler cap.
    • Improperly routed, kinked or damaged EVAP system chassis purge line from vacuum source in engine compartment.
    • Damaged EVAP purge solenoid valve.
    • Improperly routed, kinked or damaged EVAP system chassis purge line from EVAP purge solenoid valve to EVAP canister.
    • Leaking fuel tank vent valve.

    Repair EVAP system as necessary. After repairs, go to step  21. If EVAP system is okay, go to next step.

  4. Using scan tool, perform EVAP system SERVICE BAY TEST. If test passes (scan tool indicates 0.7-2.5 volts), see DIAGNOSTIC AIDS . If test does not pass, go to next step.
  5. Turn ignition off. Remove EVAP purge line from canister side of EVAP purge solenoid valve. Connect vacuum gauge to canister side of EVAP purge solenoid valve. Start engine and allow it to idle. Using scan tool, command EVAP purge solenoid valve to 50 percent. If vacuum displayed on gauge is 12 in. Hg or greater, go to step  7. If vacuum displayed on gauge is not 12 in. Hg or greater, go to next step.
  6. Turn ignition off. Disconnect vacuum source from EVAP purge solenoid valve. Connect vacuum gauge to EVAP purge solenoid valve vacuum source. Start engine and allow it to idle. If vacuum displayed on gauge is 12 in. Hg or greater, go to step  16. If vacuum displayed on gauge is not 12 in. Hg or greater, go to step  15.
  7. Turn ignition off. Remove vacuum gauge and reconnect EVAP purge line. Connect EVAP Pressure/Purge Diagnostic Station (J-41413) to EVAP system service port located on left side of intake manifold, near EVAP purge solenoid valve. Using scan tool, command EVAP vent valve on (closed). Continuously attempt to pressurize EVAP system by leaving EVAP pressure/purge diagnostic station control knob in PRESSURIZE position. Using Ultrasonic Leak Detector (J-41416), attempt to locate EVAP system leak. Repair as necessary. After repairs, go to step  21. If no leaks are found, go to next step.
  8. Check EVAP system for restrictions. Repair as necessary. After repairs, go to step  21. If no problem is found, go to next step.
  9. With EVAP system pressurized, compare EVAP pressure/purge diagnostic station pressure gauge reading to fuel tank pressure sensor reading on scan tool. Also compare readings with system depressurized. If scan tool value indicates actual EVAP system pressure, go to next step. If scan tool does not indicate actual EVAP system pressure, go to step  19.
  10. Turn ignition off. Remove EVAP purge line from canister side of EVAP purge solenoid valve and plug hose end. Disconnect chassis EVAP purge pipe (aluminum/plastic coating) at EVAP canister nylon purge pipe. Connect hand-held vacuum pump to chassis EVAP purge line. Attempt to apply 5 in. Hg vacuum. If vacuum can be obtained and held, go to next step. If vacuum can not be obtained or held, go to step  20.
  11. Disconnect vapor and EVAP purge lines from EVAP canister. Plug canister fitting for vapor line. Connect hand-held vacuum pump to EVAP purge fitting on EVAP canister. Turn ignition on, with engine off. Using scan tool, command vent valve on (closed). Attempt to apply 5 in. Hg vacuum to EVAP canister. If vacuum can be obtained and held, go to step  14. If vacuum can not be obtained or held, go to next step.
  12. Leave system connected as in previous step. Disconnect vent line at EVAP vent valve. Plug vent line at EVAP vent valve. Using hand-held vacuum pump, attempt to apply 5 in. Hg vacuum to EVAP canister. If vacuum can be obtained and held, go to step  17. If vacuum can not be obtained or held, go to next step.
  13. Check line from EVAP canister to vent valve for any defects. Repair as necessary. After repairs, go to step  21. If no problems are found, go to step  18.
  14. Remove fuel tanks. Remove tank-to-tank pipe from fuel tank vent valve quick connector and EVAP canister. Reassemble removed fuel tanks and EVAP system components on bench. Plug fuel tank vent valve pipe. Plug all remaining openings necessary for leak testing. Apply soap solution to fuel tanks and all connections. Pressurize fuel tank assembly at fuel tank fill hose to 1.5 psi (0.11 kg/cm2 ). Air bubbles will indicate leak. Repair as necessary. After repairs, go to step  21.
  15. Repair vacuum source to EVAP purge solenoid valve. After repairs, go to step  21.
  16. Replace EVAP purge solenoid valve. After repairs, go to step  21.
  17. Replace EVAP vent valve. After repairs, go to step  21.
  18. Replace EVAP vapor canister. After repairs, go to step  21.
  19. Replace fuel tank pressure sensor. After repairs, go to step  21.
  20. Replace chassis EVAP pipe as necessary. After repairs, go to next step.
  21. Using scan tool, perform EVAP system SERVICE BAY TEST. If test passes, go to next step. If test does not pass, go to step  2.
  22. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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