Tech Tip - August 2010
107 West 11th Street
Coffeyville, KS 67337
Phone: (800) 225-4813 (620) 251-4700
FAX: (620) 251-2215
Understanding and Maintaining Your Vehicle's Fuel System
The purpose of your fuel system is to provide a constant fuel flow at vehicle system pressure to the engine. A fuel pump pushes fuel from the tank and sends it under pressure to the injectors, which spray it into the engine's intake manifold. The fuel pressure is kept constant by a fuel pressure regulator.
There are two basic types of systems: those that utilize a fuel return line and those that do not. In a system with a return, the regulator is located at the engine, on the injector rail. In a returnless system, it is located inside the gas tank as part of the fuel pump assembly.
Keeping your fuel system properly maintained is vital to your vehicle's performance and fuel efficiency. A poorly maintained fuel system will eventually cause rough idling, hesitation, weak accerlation and even stalling.
Fuel System Components.
Fuel Tank: The role of the fuel tank is pretty simple: storing fuel until it's needed. But today's fuel tanks incorporate some improvements as well, such as baffles that keep the fuel from sloshing around the tank when ou speed up or slow down. Tanks also have a fuel filler pipe, a fuel outlet line and a vent system. The fuel filler cap must fit snugly and securely to keep vapors from escaping into the air (see below). Some vehicle's throw a check engine light if there is a problem with the fuel tank filler assembly.
Fuel Pump: The fuel pump sends fuel, under pressure, from the tank to the engine. In most vehicles on the road today, the fuel pump is electric and is usually installed in the fuel tank. Older cars have a mechanical fuel pump attached to the engine or an electric pump on the frame rail between the tank and the engine.. Vehciels with diesel engines make use of either a mechanical or an in-line lift pump to feed fuel to the injector pump, or use no lift pump at all.
Fuel Filter(s): The fuel filter is a vital part of the system. It traps dirt particles, rust and other substances in the fuel line. The fuel filter is especially important in fuel-injected vehicles with electric fuel pumps (which is most of today's passenger vechiles). Fuel injectors are especially susceptible to clogging, so it's important that thge filter be checked once a year and replaced every two years or 30,000 miles. A plugged fuel filter will also cause the fuel pump to work too hard to push the fuel past the blockage, leading to early pump failure.
Most cars use two filters. Once sits inside the gas tank and is typically called the strainer. The other is in the line to the fuel injectors or carburetor. Except for extreme or unusual situations where a large amount of dirt has entered the gas tank, the only filter that should ever need replaced is the in-line fuel filter. However, any time an in-tank fuel pump is replaced, the strainer must be replaced as well.
Fuel Pressure Regulator: This device keeps the fuel at a constant pressure. When fuel pressure reaches system pressure, the regulator's intrnal valve opens and allows surplus fuel to flow back into the tank. This especially occurs when the engine is idling or running at low speeds, and less fuel is required.
Fuel Filler Cap: What we commonly call the gas cap is more than just a lid. It's seal keeps fumes from the tank from leaking into the atmosphere and impacting the environment. Fumes in the tank are vented instead through a charcoal canister that traps fuel vapor. If, however, pressure in the tank reaces a certain level (which varies among vehicles) the filler cap has a pressure release valve that allows pressure to vent.
Gasoline: Gasoline is made of refined crude oil along with additives to improve performance and reduce emissions. For optimum engine performance and a healthy fuel system, when refueling your vehicle always choose a respected brand of quality gasoline, and be sure to select the exsact octane rating your owner's manual specifies.
Keeping Your Fuel Pump and Fuel System Maintained
A fuel pump in a gas tank has to endure a harsh invironment. For one thing, it's sitting in gasoline all of the time. But other ractors can take their toll as well: heat and cold and especially dirt and sediment.
Here are some easy steps for keeping your fuel pump and system in good working condition:
You can do a lot to make sure your car is reliable and fuel system is clean and safe. For help, talk to a friendly Carter Automotive representative who will answer your questions and get you the quality parts you need.
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