Ford F150 Pickup. Instruction — part 1634

Fueling Connector

The flange assembly is designed for 3000 psi (20,685 kPa) service pressure and is the refueling connection to
fill vehicle. The assembly is mounted behind fuel filler door and attached to fuel filler housing, similar to a
gasoline vehicle. This assembly consists of an NGVP1 type receptacle with a 150-micron filter (which can be
serviced), a spring loaded check valve to allow filling of vehicle and a instructionly opened bypass to provide safe
venting of fuel system. The vehicle is refueled by attaching fuel station fill nozzle to receptacle and locking into
place.

Fuel Lines & Fittings

A fuel line assembly consists of flexible hose and/or stainless steel seamless tubing, end fittings and tube nuts.
The hose is a conductive polytetrafluoroethylene (PTFE) liner reinforced with a stainless steel wire braided
covering. The fittings are inserted into hose ends and crimped into place. The stainless steel tubing contains end
fittings which are brazed to the tube. There are high pressure fuel lines that are identified by either 1/4-inch or
3/8-inch outer diameter, and a low pressure fuel line identified by a 1/2-inch outer diameter. The low pressure
fuel line has a quick-connect at one end for connection to fuel rail. The other fittings used on natural gas vehicle
to connect fuel components are SAE "O" ring face seal tube fittings. There are 2 end types: an "O" ring face
seal end and a straight thread end. On tee and elbow fittings, a washer and a positionable nut are provided to aid
in orientation of the fitting.

Fuel Rail

The fuel rail distributes low pressure fuel from chassis supply line to each fuel injector. Fuel pressure at top of
each fuel injector is maintained within 1 percent of other fuel injectors at all times, done by nearly symmetric
flow paths. The fuel rail is also designed to have minimal flow restriction by increasing cross-sectional flow
area and reducing flow path length. The fuel rail contains several other components that perform crucial
functions. See Fig. 43 . These include:

z

Injection Pressure Sensor

Measures the pressure of fuel near fuel injectors. This signal is used by PCM to adjust fuel injector pulse
width and meter fuel to each cylinder.

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Engine Fuel Temperature Sensor

Measures pressure of fuel near fuel injectors. This signal is used by PCM to adjust fuel injector pulse
width and meter fuel to each cylinder.

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Low Pressure Solenoid Shutoff Valve

Isolates fuel rail from upstream fuel system when engine is OFF. This minimizes the amount of fuel
available to flow through fuel injectors when engine is off or leak from a damaged fuel rail during and
after a crash. The valve is controlled by PCM fuel shutoff valve circuit and contains an inertia switch. The
valve is only on for one second after a key-on or whenever CKP signals are being received by PCM.

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Schrader/Service Valve

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

Provides a service port to low pressure fuel system. This valve is needed to relieve pressure in system
before and during service. This valve could also be used to monitor pressure near injectors during
diagnostic procedures.

Fuel Rail Shutoff Valve

The fuel rail shutoff valve is a normally closed valve that opens when terminal No. 80 is grounded by PCM. See
Fig. 44 . Resistance of the fuel rail shutoff valve coil is 11 ohms. When ignition switch is in ON position, power
relay is turned on. Power relay provides power to PCM and control side of fuel shutoff valve relay. Relay
provides voltage to fuel rail valve. If ignition switch is not in START position, PCM will close fuel rail shutoff
valve after one second. PCM will open valve, along with the tank valve(s), to provide fuel while cranking. The
valve will remain open when engine is running unless IFS switch is "tripped".

Fig. 44: Identifying Fuel Rail Shutoff Valve
Courtesy of FORD MOTOR CO.

Fuel Tank Shutoff Valve

The fuel tank shutoff valve is located in fuel tank(s). See Fig. 45 . When ignition switch is in OFF position, fuel
tank shutoff valves are closed and fuel in the tanks is isolated. During refueling, fuel tank shutoff valve acts as a
check valve and allows flow due to pressure differential between fuel being added from fill station and fuel in

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

the tank.

The fuel tank shutoff valve internal solenoid valves also have capability of being instructionly locked down. While
servicing vehicle, if it becomes necessary to remove the fuel tank, lock down feature provides an added measure
of safety.

The fuel tank shutoff valve has an internal Canadian Gas Association (CGA) type 9 fusible link pressure relief
device that senses internal fuel tank gas temperature. Fuel tank is vented to the atmosphere when internal fuel
tank gas temperature reaches 217°F (199°C) and melts fusible link. The escaping gas is vented through a vent
line.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline