Rollover Valve: Description and Operation

Vapor Vent:

The evaporative emission valve:

- Makes use of a small orifice and shutoff valve that tends to allow only fuel vapor, not liquid, to pass through the evaporative emission return tube to the evaporative emissions canister.
- Mounts directly to the fuel tank, using a rubber grommet.

The vapors flow through a single vapor tube to the evaporative emissions canister at the rear of the vehicle. A spring-loaded valve provides relief ahead of the orifice to the evaporative emissions canister. This valve gradually opens above 5-6 kPa (0.7-0.9 psi) to vent fuel vapors from the fuel tank to the evaporative emissions canister.

The valve also serves as a rollover valve, preventing liquid fuel from entering the evaporative emission canister in the event of a vehicle rollover.