The roll over valve sits in the top of the fuel tank and does two opposite jobs. In normal driving it lets vapor out to the EVAP system, and if the truck ends up on its roof it seals shut so fuel cannot pour out the vent. A valve that sticks closed pressurizes the tank and makes it hard to fill; one that sticks open lets liquid fuel into the canister.

Valve Details:

• Fits select Dodge Ram 1500, 2500 and 3500 trucks.
• Vents fuel vapor to the EVAP system in normal use.
• Seals the vent path if the vehicle inverts.
• Genuine Mopar valve. Sold individually.