Fuel Supply Line: Description and Operation
Hairpin Clip Connector:
FUEL LINES AND CONNECTORS
Fuel injection systems often use special kinds of fittings to ensure leakproof connections. Some high-pressure fittings use O-ring seals instead of the traditional flare connections. The O-rings are made of special materials that can withstand contact with gasoline and alcohol-blend fuels. Whenever you replace one of these O-rings, you must use a new part specifically designed for fuel system service. The O-rings used in air conditioning systems are not satisfactory.
Ford uses nylon fuel tubing with several unique push-connect fittings. Special barbed connectors are required to join sections of nylon tubing together.
Connectors that join nylon to steel tubing also have barbed ends for the nylon lines, but they use O-rings to seal the steel line. Ford uses two kinds of retainer clips on these connectors. Fittings for 5/16 and 3/8 inch lines have hairpin clips. Fittings for 1/4 inch lines have duckbill clips.
Fuel Supply Manifold Assembly:
FUEL SUPPLY MANIFOLD
The fuel supply manifold assembly is delivers high pressure fuel from the vehicle fuel supply line to the eight fuel injectors. The assembly consists of two banks of tubular fuel rails connected by two permanent crossover connections, eight injector connectors, a mounting flange to the fuel pressure regulator and mounting attachments which locate the fuel manifold assembly and provide fuel injector retention. The fuel inlet and outlet connections have push connect fittings.
Fuel Filler System:
FUEL TANK FILLER NECK
To prevent accidental filling with other than unleaded fuel, vehicles that require unleaded fuel have a special filler tube. This filler tube has a restriction in it so that the only nozzles that can be inserted are the smaller diameter nozzles of pumps dispensing unleaded fuel.
It is recommended that the amount of fuel put in the tank when filling be limited to the automatic pump shutoff. Due to the expansion of fuel during temperature increases, or overfilling ("topping off") can cause fuel overflow at the filler cap when the vehicle is standing or the cap is removed. If the vehicle has two tanks, use fuel from both tanks after fill-up to reduce fuel levels.
MECHANICAL ROLLOVER VALVE
The vapor valve assembly is used to control the flow of fuel vapor entering the fuel tank vapor delivery line which conducts vapor forward to the 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, and stabilizes pressure inside the tank. The valve assembly has a head valve which prevents the fuel tank from overfilling during refueling operation. The valve assembly also has a spring supported float assembly, which prevents liquid fuel from entering the vapor delivery line during severe handling, steep grades or in the event of vehicle rollover.
SEALED FILL CAP
The sealed cap incorporates a built-in pressure-vacuum relief valve. Fuel system vacuum relief is provided after approximately .5 inch vacuum is reached inside the tank. Pressure relief is provided when pressure inside the tank builds up approximately 1.8 psi. Under normal operating conditions, the fill cap operates as a check valve preventing vapors from escaping the tank through the cap.
VAPOR VENT
In-tank venting provides a vapor space above the gasoline surface in the fuel tank. This area is sufficient to permit adequate breathing space for the tank vapor valve assembly under all static and most dynamic condition.