Chapter 15 Fuel and Emission Control Systems 307 Copyright by Goodheart-Willcox Co., Inc. Multiport Gasoline Injection System Direct Injection System (DIS) Inline fuel filter Inline fuel pump Fuel supply line Throttle body Fuel pressure regulator Fuel injectors In-tank fuel pump In-tank fuel filter Fuel return line In-tank electric pump In-tank fuel filter Fuel return line Fuel supply line High pressure injection pump Inline filter Inline pump Injector nozzle sprays into combustion chamber Figure 15-2. Note the location of fuel lines, filters, pumps, and other parts of the fuel supply system. Fuel Line and Hose Service Faulty fuel lines and hoses are a common source of fuel leaks. Fuel hoses can become hard and brittle after being exposed to engine heat and the elements. Engine oil can soften and swell fuel hoses. Always inspect hoses closely and replace any in poor condition. Metal fuel lines seldom cause problems. However, they should be replaced when damaged or leak- ing. Remember these rules when working with fuel lines and hoses: • Place a rag around the fuel line fitting during removal to keep fuel from spraying on you or the hot engine. • Use a tubing (line) wrench on fuel system fittings. • Only use approved tubing, such as double-wall steel, for fuel lines. Never use copper tubing. • Make smooth bends when forming a new fuel line. Use a bending spring or tool. • Form only double-lap or ISO flares on the ends of the fuel line. • Reinstall fuel line hold-down clamps and brackets. If not properly supported, the fuel line can vibrate and fail. • Route all fuel lines and hoses away from hot or moving parts. Double-check clearances after installation. • Only use approved synthetic rubber hoses in a fuel sys- tem. If vacuum-type rubber hose is accidentally used, the fuel can chemically attack the hose. A dangerous leak could result. • Make sure a fuel hose slides fully over its fitting before installing the clamps. Otherwise, pressure in the fuel system could force the hose off. • Double-check all fittings for leaks. Start the engine and inspect the connections closely. • Do not bend or mishandle plastic or nylon fuel lines. If the line becomes kinked, it will create a permanent restriction. If a plastic or nylon fuel line is damaged in any way, replace it. Do not attempt to repair a damaged plastic fuel line. • Some fuel lines have a special, snap-type fitting called a push-on fitting. Do not pry the fitting apart or it will be damaged. In some cases, you may need a special tool to release the fuel line fitting for service. • When servicing push-on fuel line fittings, you may also need to replace the O-ring seal to prevent fuel leakage. Make sure you purchase a seal of the correct mate- rial, shape, and size for the fuel line and make/model vehicle. If you install the wrong seal, a fuel leak and fire can result.