Checking Evaporative Emission System
NOTE:
For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-1
under VERIFICATION TESTS to ensure system is functioning properly.
- Start engine and allow it to reach normal operating temperature. Engine must be in closed loop to perform this test. Using scan tool, select SYSTEM TESTS, then PURGE VAPORS TEST. Monitor short term adaptive value on scan tool and press "3" to flow. Short term adaptive value should change. If value changes, no problem is indicated at this time. Test is complete. If short term adaptive value does not change, go to next step.
- Turn ignition off. Inspect vacuum line from purge solenoid to EVAP canister and to fuel tank. On Cherokee, EVAP purge solenoid is mounted on a bracket at right rear of engine compartment. See Fig 1 . EVAP canister is located underneath left side of vehicle near front of rear axle. On Grand Cherokee, purge solenoid and EVAP canister are located in engine compartment, left of brake booster. See Fig 2 . On Wrangler, EVAP purge solenoid and EVAP canister are located on left side of engine compartment. See Fig 3 . On all models, replace vacuum line as necessary. If vacuum line is okay, go to next step.
- At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Turn ignition on. Using scan tool, actuate EVAP purge solenoid. Wiggle EVAP purge solenoid wiring harness and listen for EVAP purge solenoid to quit actuating. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or EVAP purge solenoid quits actuating, repair wiring where wiggling caused EVAP purge solenoid to quit actuating. If EVAP purge solenoid does not stop actuating and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.
- Inspect line from rollover valve to EVAP canister. Rollover valve is mounted in top of fuel tank, next to fuel pump module. If any fuel is in rollover valve line, replace rollover valve. Rollover valve is not serviced separately. If rollover valve is defective, fuel tank must be replaced. See FUEL TANK under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. If no fuel is in rollover valve hose, go to next step.
- Remove EVAP purge solenoid. Tap EVAP purge solenoid ports against a clean, solid surface. If foreign material falls out of ports, replace EVAP purge solenoid. If no foreign material falls out of ports, no problem is indicated at this time. Test is complete.