U.S.A. And CANADA

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

Remove the check valve. (See FUEL TANK REMOVAL/INSTALLATION .)
Verily that there is airflow when positive pressure is applied to port A.

Fig 1: Checking Airflow Pressure Applied To Port A - U.S.A. And CANADA
Courtesy of MAZDA MOTORS CORP.
- If there is no airflow, replace the breather pipe. (See FUEL TANK REMOVAL/INSTALLATION .)
Verily that there is airflow when negative pressure is applied to port A.
- If there is no airflow, replace the breather pipe. (See FUEL TANK REMOVAL/INSTALLATION .)