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Home >> Isuzu >> 1996 >> Hombre S >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Testing >> DTC P1441 - EVAP System Flow During Non-Purge >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command EVAP canister purge valve and EVAP vent solenoids on and off. If purge valve and vent solenoids click, go to next step. If purge valve and/or vent solenoid dose not click, repair wiring or replace purge valve and/or vent solenoid as necessary.
  3. Remove fuel cap. Using scan tool, observe FUEL TANK VACUUM PRESSURE. If pressure is zero in. H2O, go to step 6). If pressure is more than zero in. H2O, go to next step.
  4. If battery has been disconnected, check fuel tank pressure sensor. See SYSTEM/COMPONENT TESTS article. Replace fuel tank pressure sensor or repair related wiring as necessary. If battery has not been disconnected, go to next step.
  5. Reinstall fuel cap. Using scan tool, command EVAP vent solenoid on (closed). Zero EVAP pressure and vacuum gauges on EVAP Pressure/Purge Cart (J-41413). Connect EVAP pressure/purge cart to EVAP service port. Attempt to pressurize EVAP system to 5 in. H2O. Monitor pressure using gauge on EVAP pressure/purge cart. If pressure can be achieved, go to next step. If pressure cannot be achieved, go to step 8).
  6. Maintain EVAP system pressure at 5 in. H2O. Using scan tool, observe FUEL TANK VACUUM PRESSURE. If pressure reading is 4-6 in. H2O, go to next step. If pressure reading is not 4-6 in. H2O, check fuel tank pressure sensor. See the appropriate SYSTEM/COMPONENT TESTS article. Replace fuel tank pressure sensor or repair related wiring as necessary.
  7. Disconnect vacuum hose at EVAP canister purge valve (from throttle body). Connect a vacuum pump to EVAP canister purge valve vacuum source fitting. Apply 15 in. Hg. Using scan tool, command EVAP canister purge valve on. If vacuum is released, go to step 10). If vacuum holds, go to next step.
  8. Check EVAP canister purge valve vacuum hoses for correct routing. If vacuum hoses are routed incorrectly, go to step 11). If vacuum hoses are routed correctly, see DIAGNOSTIC AIDS. If vacuum hoses are routed correctly, go to step 11).
  9. Replace EVAP canister purge valve. After repair is completed, go to step 12).
  10. Correct vacuum hose routing. After repair is completed, go to next step.
  11. Start engine. Remove fuel cap. Using scan tool, command EVAP vent solenoid on (closed) and EVAP canister vent valve off (zero percent). Reinstall fuel cap. While monitoring FUEL TANK VACUUM PRESSURE on scan tool, raise engine speed to 2500 RPM. If pressure is zero in. H2O, system is functioning properly. If pressure is more than zero in. H2O, repeat step 2).
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