First things first delivering the proper quantity of fuel to the engine is imperative. The fuel is drawn from the fuel tank by a mechanical or electric fuel pump. All with Electronic fuel injection have an electric fuel pump. Fuel Injector require larger fuel pressure.
Cars with carburetors, generally, have a mechanical fuel pump. Electric fuel pumps are placed inside the fuel tank as part of the fuel-sending unit.
Mechanical fuel pumps are fastened on the engine block and are usually driven by the camshaft.
The fuel pump delivers the fuel through steel lines to the fuel filter (not copper or aluminum). The fuel filter removes any particles of dirt or metal or other debris that may be in the fuel. Some fuel filters will also remove moisture from the fuel as well. From the filter it goes either to the carburetor or the fuel rails then to the fuel injectors.
In the case of the carburetor, the fuel is mixed with air when air is sent thru venturi to form the optimum fuel mixture for the current conditions.
The ideal fuel mixture is 14.7:1. That is to say 14.7 parts of air to 1 part of fuel. This is very difficult for a carburetor to do because it has no idea how much air is going into the engine. In order to do it properly, you need a four-gas emission analyzer to see what % of carbon monoxide (CO) and how many parts per million (PPM) of hydrocarbons (HC) is being emitted by the engine. By turning the adjuster screws on the carburetor and watching the emissions, you can come pretty close. In some states there are specific levels of CO and HC that must be met or the vehicle is not considered street legal. From the carburetor the fuel mixture travels through the intake manifold and is delivered to each cylinder.
In a fuel-injected engine, fuel is introduced into the engine by the fuel injector which is computer controlled. There are two, basic, types of fuel injection. Port fuel injection (PFI) and throttle body injection (TBI). In TBI there is one or two injectors mounted in housing similar to a carburetor and the fuel is constantly injected into the air stream. In PFI there is one injector for each cylinder mounted in the intake manifold so that it is pointing towards the intake valve. By opening and closing, the injectors can, very precisely, meter the correct amount of fuel to the engine as determined by the Powertrain Control Module (PCM).
also, there is a fuel pressure regulator that controls the pressure of the fuel in the lines. It has a vacuum line connecting to the intake manifold to measure manifold vacuum. As engine RPM increases, manifold vacuum decreases causing the fuel pressure to increase.
The stock fuel system on the Ford Mustang in only antiquate for stock application. If you plan on boosting the horsepower in that Mustang GT, Cobra or Mach 1 than you will need to increase the flow of fuel to the cylinder in order to get the proper amount combustion in order to increase the autos power.
The fuel system of the Chevy Camaro is starving and the people who buy them know this all too well. That is why the owners of the Chevy Camaro start by upgrade the fuel system as they start to reach a honorable horsepower. You should pay particular attention to the amount of fuel mixing with air in the Chevy Camaro. The factory Camaro is a waiting for its after market bolt on parts to bring it to the horsepower it is meant to have. This is something that has been happening since the cars rolled off the line and that is why the upgrades for the Chevy Camaro are selling so hot right now as the fuel system are much better when it has been completely replaced and a new system takes its place. Put the right combination of parts into Chevy Camaro fuel system and you find nothing but great things will happen to your Camaro.
The Corvette came out with a great fuel system but that has not stopped the high performance gear heads from upgrading it nonetheless. Make sure that you choose the right fuel system for your Corvette or you could find yourself with something that is not as adequate as the original and may even slow down the motor and rob it of its great horsepower.
The Pontiac GTO fuel system is in need of some attention. It has a great motor and doesn't quite have the proper amount of fuel to bring the motor to its peak performance. The Pontiac GTO will benefit greatly from improvements to its fuel system.
Parts of the fuel system
The purpose of the carburetor is to supply and meter the mixture of fuel vapor and air in relation to the load and speed of the engine. Because of engine temperature, speed, and load, perfect carburet ion is very hard to obtain. The carburetor supplies a small amount of a very rich fuel mixture when the engine is cold and running at idle. With the throttle plate closed and air from the air cleaner limited by the closed choke plate, engine suction is amplified at the idle-circuit nozzle. This vacuum draws a thick spray of gasoline through the nozzle from the full float bowl, whose fuel line is closed by the float-supported needle valve. More fuel is provided when the gas pedal is depressed for acceleration. The pedal linkage opens the throttle plate and the choke plate to send air rushing through the barrel. The linkage also depresses the accelerator pump, providing added gasoline through the accelerator circuit nozzle. As air passes through the narrow center of the barrel, called the "venturi", it produces suction that draws spray from the cruising-circuit nozzle. The float-bowl level drops and causes the float to tip and the needle valve to open the fuel line. To cause a liquid to flow, there must be a high pressure area (which in this case is atmospheric pressure) and a low pressure area. Low pressure is less than atmospheric pressure. The average person refers to a low pressure area as a vacuum. Since the atmospheric pressure is already present, a low pressure area can be created by air or liquid flowing through a venturi. The downward motion of the piston also creates a low pressure area, so air and gasoline are drawn through the carburetor and into the engine by suction created as the piston moves down, creating a partial vacuum in the cylinder. Differences between low pressure within the cylinder and atmospheric pressure outside of the carburetor causes air and fuel to flow into the cylinder from the carburetor.
Fuel lines, which connect all the units of the fuel system, are usually made of rolled steel or, sometimes, of drawn copper. Steel tubing, when used for fuel lines, is generally rust proofed by being copper or zinc plated. Fuel lines are placed as far away from exhaust pipes, mufflers, and manifolds as possible, so that excessive heat will not cause vapor lock. They are attached to the frame, the engine, and other units in such a way that the effect of vibration is minimal, and so that they are free of contact with sharp edges which might cause wear. In areas where there is a lot of movement, as between the car`s frame and rubber-mounted engine, short lengths of gasoline resistant flexible tubing are used. Steel lines and flexible hoses carry the fuel from the tank to the fuel rails then to the engine. When servicing or replacing the steel lines. Steel lines must be replaced with steel. When replacing flexible rubber hoses, proper hose must be used. Ordinary rubber such as used in vacuum or water hose will soften and deteriorate. Be careful to route all hoses away from the exhaust system.
Two types of fuel pumps are used in automobiles; mechanical and electric. All fuel injected cars today use electric fuel pumps, while most carbureted cars use mechanical fuel pumps. Mechanical fuel pumps are diaphragm pumps, mounted on the engine and operated by an eccentric cam usually on the camshaft. A rocker arm attached to the eccentric moves up and down flexing the diaphragm and pumping the fuel to the engine. Because electric pumps do not depend on an eccentric for operation, they can be located anywhere on the vehicle. In fact they work best when located near the fuel tank.
Many cars of today, locate the fuel pump inside the fuel tank. While mechanical pumps operate on pressures of 4-6 psi (pounds per square inch), electric pumps can operate on pressures of 30-40 psi. Current is supplied to the pump immediately when the key is turned. This allows for constant pressure on the system for immediate starting. Electric fuel pumps can be either low pressure or high pressure. These pumps look identical, so be careful when replacing a fuel pump that the proper one is used. Fuel pumps are rated by pressure and volume. When checking fuel pump operation, both specifications must be checked and met.
The fuel filter is the key to a properly functioning fuel delivery system. This is even more true with fuel injection than with carbureted cars. Fuel injectors are more susceptible to damage from dirt because of their close tolerances. When the filter clogs, the electric fuel pump works so hard to push past the filter that it burns itself up. Most cars use two filters. One inside the gas tank and one in-line of the fuel system. Unless some severe and unusual condition occurs to cause a large amount of dirt to enter the gas tank, it is only necessary to replace the filter in the line.
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