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HOMESERVICE MANUALSCHEVROLET1998SUBURBAN K2500, 7.4 J, PART TIMEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 2 (ENGINE CONTROLS - TESTS W/CODES - 5.7L)DIAGNOSTIC TROUBLE CODESDTC P0440 - EVAP SYSTEMDIAGNOSTIC PROCEDURES
1998 Chevrolet Suburban K2500, 7.4 J, Part Time

Diagnostic Procedures

1998 Chevrolet Suburban K2500, 7.4 J, Part TimeSECTION Diagnostic Procedures
WARNING: This page is about a different variant/trim than selected.
  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . Retrieve and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
  2. Check if DTCs P0446, P0452 or P0453 is set. If any of these DTCs are set, diagnose affected DTC(s). If no other DTCs are set, go to next step.
  3. Turn ignition off. Remove fuel cap. Turn ignition on. Using scan tool, read FUEL TANK VACUUM. If scan tool displays zero in. H2O, go to next step. If scan tool does not display zero in. H2O, repair faulty fuel tank sensor circuit.
  4. Zero pressure and vacuum gauges on EVAP Pressure/Purge Diagnostic Station (J 41413). Reinstall fuel cap. Read and Record FAIL RECORDS data for DTC P0440. Clear DTCs. Using scan tool, command EVAP vent solenoid ON (closed). Connect EVAP pressure/purge diagnostic station to EVAP service port. Using diagnostic station, attempt to pressurize EVAP system to 5 in. H2O. If specified pressure is achieved, go to next step. If specified pressure is not achieved, go to step 6).
  5. Maintain EVAP system pressure at 5 in. H2O. Using scan tool, read FUEL TANK VACUUM. If scan tool displays 5 in. H2O, go to step 9). If scan tool does not display 5 in. H2O, go to step 8).
  6. Disconnect fuel tank vapor and EVAP purge lines from EVAP canister. Plug fuel tank vapor line fitting at EVAP canister. Connect a hand-held vacuum pump to EVAP purge line fitting at EVAP canister. Ensure EVAP vent solenoid is still commanded ON (closed). Attempt to apply 5 in. Hg to EVAP canister. If vacuum is maintained as specified, go to step 12). If vacuum cannot be maintained as specified, go to next step.
  7. Leave system connected as in previous step. Disconnect and plug vent valve hose. Using a hand-held vacuum pump, apply 5 in. Hg. If vacuum can be obtained and held, go to step 17). If vacuum cannot be obtained or held, go to step 11).
  8. Disconnect fuel tank vapor line from canister. Attempt to pressurize EVAP system using EVAP Pressure/Purge Diagnostic Station (J 41413). Start engine. Monitor pressure on diagnostic station gauge. If 5 in. H2O can be obtained and held, go to step 18). If 5 in. H2O cannot be obtained or held, go to step 15).
  9. Disconnect purge line from canister. Connect vacuum gauge to service port of diagnostic station. Start engine. Command EVAP solenoid valve to 100 percent. If vacuum reading is 12 in. Hg or greater, see DIAGNOSTIC AIDS. If vacuum reading is not 12 in. Hg, go to next step.
  10. Disconnect purge line from purge solenoid valve. Start engine. Using scan tool, command EVAP purge solenoid purge solenoid ON (100 percent). If vacuum reading is 12 in. Hg or greater, go to step 14). If vacuum reading is not 12 in. Hg or greater, go to step 16).
  11. Check if vent hose is disconnected or damaged. Check EVAP canister for damage. Repair as necessary. After repairs, go to step 19). If no problem is found, go to step 18).
  12. Check for missing or faulty fuel filler cap. Check for disconnected, leaking or damaged fuel tank vapor line or EVAP purge line. Repair as necessary. After repairs, go to step 19). If no problem is found, go to next step.
  13. Using scan tool, command EVAP vent solenoid ON (closed). With EVAP pressure/purge diagnostic station connected to EVAP service port, continuously attempt to pressurize EVAP system to 15 in. H2O by leaving diagnostic station control knob in PRESSURIZE position. Using Ultrasonic Leak Detector (J 41413), locate and repair EVAP system leak. It may be necessary to lower fuel tank to check connections at top of tank. Repair leak as necessary. After repairs, go to step 19).
  14. Repair restriction in EVAP purge line. After repairs, go to step 19).
  15. Repair restriction in fuel tank vapor line. After repairs, go to step 19).
  16. Replace EVAP purge solenoid valve. After replacing solenoid valve, go to step 19).
  17. Replace EVAP vent valve. After replacing vent valve, go to step 19).
  18. Replace EVAP canister. After replacing canister, go to next step.
  19. Turn ignition on, engine off. Using scan tool, command EVAP vent solenoid ON (closed). Using diagnostic station, pressurize EVAP system to 15 in. H2O. Monitor EVAP diagnostic station pressure gauge. Turn diagnostic station rotary switch to HOLD position. If pressure decreases to less than 10 in. H2O within 2 minutes, system is okay. If pressure does not decrease to less than 10 in. H2O within 2 minutes, go to next step.
  20. Using scan tool, select DTC, CLEAR INFO function. Perform SERVICE BAY TEST for EVAP system. After performing test, go to next step.
  21. Using scan tool, select Read and Record INFO, REVIEW INFO function. Check if any undiagnosed DTCs are displayed. Diagnose affected DTCs. If no additional DTCs are displayed, system is okay.
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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.