Rollover Valve: Description and Operation

Pressure Relief/rollover Valve:

PURPOSE
Prevents fuel system damage, by venting the system in the event of high internal pressure or vacuum.

Prevents fuel and vapors from escaping into the atmosphere, (except under extreme conditions, see above).

OPERATION
Rollover Operation
Prevents fuel from escaping, (through the EVAP System), in the event of vehicle rollover, the valve will become inverted. In this position the plunger is forced against the guide plate and raw fuel is prevented from flowing through the valve orifice into the vent tube.

Vents excess pressure or vacuum to the atmosphere when calibrated valve setting is exceeded.

Pressure Relief Operation
One way valve allows fuel and vapors to be vented to the EVAP canister.