Pressure and Vacuum Relief System

Fuel Tank Filler Cap

The fuel tank filler cap (9030) is sealed and includes a built-in pressure-vacuum relief valve. Fuel system vacuum relief is provided after 3.5 kPa (0.50 psi) and pressure relief after 11.0 kPa (1.6 psi). Under normal operating conditions, the fuel tank filler cap operates as a check valve, allowing air to enter the tank as fuel is used, while preventing vapors from escaping the tank through the cap.

NOTE: Use of an aftermarket fuel tank filler cap other than an authorized Ford/Motorcraft service part could result in damage to the fuel system or improper system operation if not properly designed/manufactured for pressure-vacuum relief. Customer warranty is void for fuel tank or fuel system damage resulting from the use of such caps.

Evaporative Emission Separator

Fuel Vapor Valve

The evaporative emission canister valve (9B963) is in line with the evaporative emissions canister (EVAP canister) (9D653) and controls the flow of fuel vapors out of the evaporative emissions canister. It is a normally closed valve that opens with vacuum input. Operation of the evaporative emission canister valve is shown in the following illustration. Also shown are views of typical evaporative emission canister valves.

Fuel Vapor Valve, Typical

Item	Part Number	Description
1	—	Vapor Inlet Port (Connects to Fuel Vapor Canister)
2	—	Purge Outlet Port (Large 63mm) (1/4 Inch Nominal O.D.) Connects to Vacuum Source
3	—	Signal Vacuum Port (48mm) (3/16 Inch Nominal O.D.) Connects to Control Vacuum Source
4	—	Vapors Flow Out (with Vacuum On)
5	—	Diaphragm Is Normally Held Closed by Spring
6	—	Vent Port (Part of 9B963)
7	—	Vapor Inlet Port (Part of 9B963)
8	—	Purge Port (Part of 9B963)
9	—	Signal Vacuum Port (Part of 9B963)

Evaporative Emission Valve, 5.8L MFI and 7.5L MFI Engines

The evaporative emission valve (9B593) mounted on the top of the fuel tank (9002) is used to control the flow of fuel vapor entering the fuel tank vapor delivery line that conducts vapor forward to the evaporative emissions canister in normal circumstances. If, due to extreme conditions, excessive pressure is generated inside the tank, the purge port opens up, allowing fuel vapor to escape to the atmosphere, stabilizing pressure inside the fuel tank. The evaporative emission valve has a head valve that prevents the fuel tank from overfilling during refueling operation. The evaporative emission valve also has a spring supported float assembly, which prevents liquid fuel from entering the vapor delivery tube during severe handling, steep grades or in the event of vehicle rollover.

Evaporative Emission Valve