Operation

OPERATION

All models pass a full 360 degree rollover test without fuel leakage. To accomplish this, fuel and vapor flow controls are required for all fuel tank connections.

All models are equipped with either one or two check valves mounted into the top of the fuel tank (or pump module). On the PZEV system the check valves are inside of the fuel tank. The valves are non-serviceable parts.

An evaporation control system is connected to the check valve(s)/control valve to reduce emissions of fuel vapors into the atmosphere, when the tank is vented due to vapor expansion in the tank. When fuel evaporates from the fuel tank, vapors pass through vent hoses or tubes to a charcoal canister where they are temporarily held. When the engine is running, the vapors are drawn into the intake manifold. In addition, fuel vapors produced during vehicle refueling are allowed to pass through the vent hoses/tubes to the charcoal canister(s) for temporary storage (prior to being drawn into the intake manifold).

The ESIM (Evaporative System Integrity Monitor), while physically different than the NVLD system, performs the same basic function as the NVLD does - controlling evaporative emissions. The ESIM has been simplified because the solenoid used on the NVLD is not used on the ESIM.

INLET CHECK VALVE

All vehicles have an inlet check valve on the inside of the fuel tank at the filler inlet.

The valve prevents fuel from splashing back during vehicle refueling. The valve is a non-serviceable item.