Flow of Diagnosis

INSPECTION and VERIFICATION
1. Verify the vehicle owner's concern by trying to duplicate the condition.
2. Inspect to determine if any of the following mechanical concerns apply:
- Hissing sound as the fuel tank filler cap is removed.
- release of pressure as the fuel tank filler cap is removed.
3. If the inspection reveals obvious concern(s) that can be readily identified, service as required.

Evaporative Emission Diagnosis:

4. If the concern(s) remain after the inspection, determine the symptoms and go to the Symptom Chart.