Fuel System - General Information

FUEL SYSTEM

WARNING: Do not modify the system configuration or components, or install components or parts not specially designed for use with natural gas. Ford Motor Company has specially designed the materials, components and system configuration for the 4.6L Crown Victoria natural gas vehicles, and each particular system is precisely calibrated for efficient operation. The use of different parts or materials can produce an untested configuration that could result in fire or personal injury, or cause engine damage.

NOTE:
- It is important that your natural gas vehicle be correctly maintained by Ford natural gas trained personnel. If a problem occurs, it is important that correctly trained personnel diagnose the cause. If the problem relates to the fuel system, correct new part installation is imperative to keep your vehicle operating at normal performance. Natural gas components and gasoline fuel components are not interchangeable. If your vehicle is not serviced in accordance with natural gas-fueled vehicle procedures, damage can occur and your warranty may be invalidated.
- All standard production components and systems receive routine service under base warranty procedures.

When servicing the fuel system, observe the following information:
- All 4.6L CNG engines use a closed-type positive crankcase ventilation (PCV) system and an exhaust emission system to control engine emission within government specifications.
- To maintain the required exhaust emission levels, the fuel system must be kept in correct operating condition.
- The natural gas fuel system must be adjusted to specifications listed in the applicable Computers and Control Systems.
- Additional engine performance checks are required to keep the exhaust emissions at the specified minimum pollutant level. Refer to the Pre-Delivery Manual for these performance checks and recommended intervals.

Always refer to the Master Parts Catalog for parts usage and interchangeability before installing any component of the fuel system.







Fuel Tank Solenoid Valve
The fuel tank solenoid valves are located on each fuel tank, one per fuel tank. The solenoid valve is a normally closed valve that opens when energized. With the key off, each solenoid valve is closed to isolate the fuel tanks from the rest of the fuel system. The solenoid valves are wired on the same circuit that a gasoline vehicle would use for the fuel pump. The circuit uses the inertia fuel shutoff (IFS) switch just as a gasoline fuel pump would, opening the circuit if the IFS switch opens. During fueling, the solenoid valve acts as a check valve and allows fuel flow into the fuel tank due to the pressure differential between the fuel being added at the fill station and the fuel tank internal pressure. The solenoid valve has the capability of being manually locked down through the solenoid valve manual lock-down jackscrew located on the solenoid valve. This feature provides an extra measure of safety when service of the fuel system becomes necessary, as well as providing a means to isolate each individual fuel tank from the rest of the system.







Fuel Pressure Regulator-Coalescer/Filter Assembly
Natural gas vehicles are equipped with a fuel pressure regulator-coalescer/filter assembly. The coalescer/filter assembly separates, filters and stores any contamination and moisture found in the fuel system, preventing moisture from entering the engine. The filter can be disassembled to service the filter element. The drain plug on the bottom of the housing allows the draining of water that has accumulated in the fuel system. The filter should be drained at regular intervals, such as each oil change. The fuel pressure regulator is a single stage pressure reducing regulator which takes the natural gas from tank pressure of 1,379 to 20,685 kPa (200 to 3,000 psi) and regulates it to engine fuel injector pressure of 724 to 862 kPa (105 to 125 psi). When reducing the pressure, the fuel temperature drops significantly, causing extremely cold temperatures of -177°C (-160°F) that may damage fuel system components as well as causing water vapor present in the fuel to condense and freeze, plugging up the fuel system. Engine coolant is circulated to the fuel pressure regulator to prevent this by warming the fuel.

Typical Vent Stack Installation:

Typical Vent Stack Installation
Refer to the illustration for a typical vent stack installation.

Fuel Tank Installation:

Fuel Tank Location and Arrangement
Refer to the illustration for the fuel tank installation.