Types of motor fuel pumps - Cars Info 24

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Monday, January 20, 2020

Types of motor fuel pumps

The fuel pump is usually not always an essential part of the car or any machine that has an internal combustion engine, while many cars, especially the old ones, do not need a fuel pump at all, only gravity needs to fuel the engine from the  fuel tank or under high pressure to the fuel injection system in the car, the motors that use carburetors usually use mechanical pumps for fuel as they are placed outside the fuel tank, while the engines that use fuel injection are used as electric pumps and are placed  Inside the fuel tank, and there are some engines that use fuel injection contain two pumps, the The first pump operates under low pressure or provides large amounts of fuel and the second works under high pressure or provides small amounts of fuel and is near the engine  itself.
Mechanical pumps


 Mechanical fuel pump installed near the front of the cylinder

 Before it was widely relied on electronic injection systems, most of the car-powered car engines used a mechanical fuel pump to transfer fuel from the fuel tank to the carpenter's fuel containers, and most mechanical fuel pumps are diaphragm type pumps which are a type of positive displacement pumps,  The diaphragm pumps contain the need for a chamber that increases and decreases in size due to the presence of a flexible diaphragm similar to its piston pump, and at the top there is a non-return valve on both the inlet and outlet of the pump room to make the fuel go only one path.  Commonly, these are pumps that are installed at the top of the engine, and by contracting the veil to the lower dead point the volume of the pump chamber increases and consequently the pressure inside it increases, allowing the fuel to rush inside the pump from the tank that is affected by air pressure, and when the diaphragm of the pump returns to the dead point  The upper action by the spring of the diaphragm, this leads to pressure on the fuel inside the pump compartment causing pressure of fuel and made it pass through the exit valve of the pump heading to the carriers, and the pressure that causes the movement of fuel in the pump is limited and related to the force that the veil spring affects.

 The carburettor contains a container where the fuel is received from the pump, and when the fuel level in the vessel reaches a certain level the intake valve in the carburetor is closed preventing the fuel pump from pumping any additional fuel to the carburettor, at which point it keeps any additional fuel trapped inside the pump unable to exit from  The inlet or outlet, remains there in the pump room until the carburetor valve is re-opened.

 Because on one side of the pump diaphragm there is fuel under pressure and the other side is attached to the engine crank shaft box, a slip of that veil (a common problem in the pump) causes the fuel to leak into the crank shaft.

 The pump creates negative pressure to pull the fuel through the fuel line, however the low pressure between the pump and the fuel tank in addition to the engine heat and air heat can all this lead to the evaporation of fuel in the intake lines, and this causes a fuel shortage inside the fuel pump designed to pump  Liquids, not steam, and thus the pump cannot add fuel to the engine, causing the engine to malfunction, and this situation is different from the blockage that occurs with steam when boiling of fuel occurs in fuel lines due to the high degree of engine warming on the other side of the pump on the one side of the carriers and not on the side of the tank,  Generally, the C pumps  Mechanical arrays do not generate as much pressure greater than 10-15 pounds per square inch, which is more than suitable for most carburettors.

 As a result of the development of engines from carburetor engines to fuel injection engine systems, mechanical pumps for pumping fuel have been replaced by electrical ones, because fuel systems operate with high efficiency at high fuel pressures (about 40-60 pounds per square inch) which is pressure greater than  Which generates hijab pumps, and electric fuel pumps are usually placed inside the fuel tank in order to use the fuel inside the tank to cool the pump and to ensure a steady rate of fuel supply within the engine.

 Another benefit of the presence of the pump inside the fuel tank is that the pumps inside the engine can draw air as a result of the lack of tight connections well which is difficult to diagnose among us if any leakage inside the pressure path will reveal itself directly with the fuel leak, and the danger of the pumps placed  Inside the tank it puts the fullest fuel tracks (from the tank to the engine) under permanently high pressure, that is, a leak will be quickly detected but it is dangerous.

 Electric fuel pumps work directly as soon as they are turned on unless a protection device is installed to protect the pump from any danger if a fuel leak occurs as a result of a malfunction or accident. Mechanical fuel pumps are safer due to the low operating pressure and stop working once the engine stops.

Electric pumps


 Electric fuel pump


 Piston pump

 Electric fuel pumps have their own motor and are driven by the engine's control unit, and their motor drives fuel from the tank to the engine through fuel paths, and electric pumps typically operate under high pressures at a rate of (50-200 pounds per square inch), and there is also  Pumps are placed inside the tank and others are placed outside. The fuel pumps that are placed inside the tank are placed at the bottom of the fuel tank, and this is the most common situation. As for the electric pumps that are placed outside the tank, they are usually placed on the outside of the fuel tank.

 In many modern cars, electric fuel pumps are placed outside the tank, and the pump affects positive pressure on the fuel, causing the fuel to be pushed to the engine, the higher the fuel pressure, the higher its boiling point, and the presence of the pump inside the fuel tank makes the pump rarely deal with fuel steam less  What happened in the engine is because it is immersed in a cold liquid, and there is another benefit to putting the pump inside the fuel tank, which is that it will be less vulnerable to a combustion in it, as the electrical components of the pump can explode and ignite the existing fuel vapor, but the liquid will not ignite, so one of the most  The  Safe places to put the pump is inside the fuel tank, and in most cars the fuel pumps pump fuel at a steady rate and the unused fuel is returned again, this reduces the possibility of boiling fuel as it is not kept next to the hot engine for a long time.

 The pump does not operate once the ignition has started, rather it makes the ignition an electric switch that gives a signal of greater current to the pump for it to work, and cars that operate with fuel injection systems have a motor control unit that is programmed with a program that turns off the pump even if the engine is running, and in the event of a collision  This program will prevent the flow of fuel and leakage from any fuel path that was cut in the accident or collision, in addition to that, the cars have an electric switch and are usually located under the front passenger seat, which works as soon as a collision occurs and works to close the fuel pump in the event of the car rolling over.

 And some engine control systems are programmed to close the fuel pump directly if an oil pressure drop is detected so that the engine does not suffer or is subject to permanent problems.

 The oil dispatcher is usually installed from an electric fuel pump, a fuel filter, and an electronic device used to measure the amount of fuel in the tank through a floating body connected to a sensor that transmits data to the fuel gauge up to date.

Turbocharged pumps

 Many jet engines, such as rocket engines, use turbine-type centrifugal pumps that are driven by a gas turbine and in some cases a compressor jet engine is used.

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