Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Test Step 3 - EVAP Leak Detection
A thorough inspection of the EVAP system hoses, tubes, and connections may save time in diagnosis. Look for physical damage or signs of wetness at connections. The strong smell of fuel vapors may aid diagnosis also.
- To continue testing, you will need Miller Tool #8404A evaporative emissions leak detector.
- Remove the AIR supply hose from the service port (if equipped) or from the #8404-ADP adapter.
- Connect the smoke supply tip (black hose) to the service port (if equipped) or to the #8404-ADP adapter.
- Set the smoke/air control switch to SMOKE.
The flow meter indicator ball will not move in the smoke mode.
- Press the remote smoke/air start button.
Make sure that smoke has filled the EVAP system by continuing to press the remote smoke/air start button, remove the vehicle fuel cap, and wait for the smoke to exit. Once smoke is detected, reinstall the fuel cap.
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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.