Fuel Tank

The fuel tank is blow-molded of high-density polyethylene. This material is multi-layer in construction to enhance its ability to minimize leakage of fuel vapors to the atmosphere (impermeability). It is generally 4.0 mm to 5.0 mm (0.16 in. to 0.20 in.) in thickness and incorporates two valves which operate during the refueling process.

Both these valves are not serviceable. One is molded into the fuel tank shell (fill limit vent valve - FLVV) and the other is part of the fuel pump module (grade vent valve).
^ Fill Limit Vent Valve (FLVV) - Located on the top, rear surface of the fuel tank, next to the fuel pump module. This is a buoyant float type valve which controls the flow of fuel vapor into the EVAP canister during refueling. The operation of the valve controls fuel tank capacity during the refueling process. (Refer to "Theory of Operation - Fuel Filling and ORVR"). The valve also prevents liquid fuel from escaping if the vehicle is involved in a roll-over accident.
^ Grade Vent Valve - Located at the upper end of fuel pump module on the fuel line that routes fuel vapor. This valve's function is to provide a vent path for fuel vapors when the tank is full. It also prevents liquid fuel from escaping the fuel tank if 1) the vehicle is operated or parked on an incline or 2) the vehicle is involved in a roll-over accident.