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EVAP Purge/Seal Leak Test

EVAP Purge/Seal System Smoke Test Procedure

Tip : ONLY use and EVAP certified smoke machine for this test procedure. These will usually output 1psi or less. Use of anything other than that could cause damage to the system or create a safety issue.

Tip : Before beginning ensure that you have a fully functional scan tool.
  1. Verify smoke machine operation: Watch
  2. Hook up to a testing point of the EVAP system: Watch
    Tip : If hooking up to the EVAP side of the purge solenoid, don't forget to verify the purge solenoid is sealed and not the source of the leak. Click here for more info (link to purge page)
  3. Saturate EVAP system with smoke: Watch
    Tip : Remove gas cap to ensure smoke has traveled through entire system. Reinstall gas cap to continue the test.
  4. Force the vent solenoid closed using a full function scan tool or a set of fused jumper wires: Watch
  5. With a scan tool, watch fuel tank pressure sensor to ensure pressure is building in the EVAP system: Watch
  6. If the smoke machine contains a flow meter, watch gauge for flow.: Watch
  7. Using a high intensity flashlight, Inspect system for leaking smoke
    Tip : Small amounts of smoke can be very difficult to see. Some leaks may be found by listening for a hissing noise or smelling for fuel as pressure is forcing fuel vapor from the EVAP system.