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Home >> Isuzu >> 1999 >> Trooper Part Time >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Trouble Code Identification >> DTC P1441: EVAP System Flow During Non-Purge (3.2L) >> Diagnostic Aids
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Diagnostic Aids

An intermittent may be caused by a cracked or punctured EVAP canister, damaged or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Monitor FUEL TANK VACUUM display while moving EVAP connections and related harnesses. Change in scan tool display will indicate area of fault. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

  1. Perform On-Board Diagnostic (OBD) System Check. See BASIC DIAGNOSTIC PROCEDURES article. After performing OBD system check, go to next step.
  2. Remove fuel cap. Using scan tool, observe FUEL TANK VACUUM. If pressure is zero in. H2 O, go to next step. If pressure is more than zero in. H2 O, see FUEL TANK PRESSURE SENSOR in SYSTEM & COMPONENT TESTING article.
  3. Zero pressure and vacuum gauges on EVAP Pressure/Purge Cart (J41413). Reinstall fuel cap. Read and record FAIL RECORDS data for DTC P1441. Clear DTCs. Using scan tool, command EVAP vent solenoid ON (closed). Connect EVAP pressure/purge cart to EVAP service port. Using EVAP pressure/purge cart, attempt to pressurize EVAP system to 5 in. H2 O. If specified pressure is not achieved, to step  5. If specified pressure is achieved, go to next step.
  4. Maintain EVAP system pressure at 5 in. H2 O. Using scan tool, read FUEL TANK VACUUM. If scan tool does not display -5 in. H2 O, see FUEL TANK PRESSURE SENSOR in SYSTEM & COMPONENT TESTING article. If scan tool displays -5 in. H2 O, go to next step.
  5. Disconnect vacuum source line at engine for EVAP purge solenoid. Connect a vacuum pump to EVAP canister purge valve vacuum source fitting. Apply 15 in. Hg vacuum. If vacuum does not hold, go to step  7. If vacuum holds, go to next step.
  6. Check EVAP canister purge valve vacuum hoses for correct routing. If vacuum hoses are routed incorrectly, repair as necessary and go to step  8. If vacuum hoses are routed correctly, check for an intermittent problem. See DIAGNOSTIC AIDS .
  7. Replace EVAP canister purge valve. Retest system.
  8. Start engine. Remove fuel cap. Using scan tool, command EVAP vent solenoid ON (closed) and EVAP purge solenoid OFF (0 percent). Reinstall fuel cap. Monitor scan tool FUEL TANK VACUUM display while holding engine speed at 2500 RPM. If pressure is zero in. H2 O, repair is complete. If pressure is not zero in. H2 O, return to last step completed and continue repair.
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