Probable Causes
- Loose fuel cap.
- Defective fuel cap relief valve, or incorrect relief pressure.
- Fuel overflow limiter valve failed.
- Purge line or vapor line is clogged.
- Fuel tank, purge line or vapor line leaks.
- Purge solenoid failed.
- Ventilation solenoid failed.
- Fuel Tank Differential Pressure (FTDP) sensor failed.
- Clogged or leaking EVAP canister.
- Use of incorrect fuel.