The fuel supply system. Injection system description and operation


2019-11-30 09:20:22




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The fuel supply System is necessary for admission of fuel from the fuel tank, further filtering, as well as the formation of an oxygen-fuel mixture passing to the cylinders of the engine. Currently, there are several types of fuel systems. The most common in the 20th century was carbureted, but today the increasing popularity of the injection system. There was a third – there, which was good only because it allows to reduce fuel consumption. Let's take a closer look at the injection system and will understand its principle of operation.a fuel supply system

General provisions

Most modern systems, engine fuel supply is similar. The difference may be only at the stage of mixing. The composition of the fuel system includes the following components:

  1. Fuel tank – compact product has a pump and filter for purification from mechanical particles. The main purpose – the storage of fuel.
  2. Fuel lines form a complex hose and tubing to move fuel from the tank to the mixing system.
  3. Device mixing. In our case we will speak about the injector. This node is designed to receive the emulsion (air-fuel mixture) and feeds it to the cylinders in the cycle of operation of the motor.
  4. The Block of management of system of mixing. Is only installed on fuel-injected engines, due to the need for control of sensors, injectors and valves.
  5. Fuel pump. In most cases submerged. The motor of small capacity, which is connected to the liquid pump. Lubrication of the fuel is realized, and the long-term use of the vehicle with a fuel quantity less than 5 liters may result in motor failure.

In a nutshell, the injector – point flow of fuel through the nozzle. The electronic signal comes from the control unit. Despite the fact that the injector has a number of advantages over a carb, it has not been used. This was due to the technical complexity of products, and low maintainability of the parts that have failed. Currently, point injection systems have virtually replaced the carburetor. Let's take a closer look at what a good injector and what are its features.


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Features of the fuel handling system

Car has always been the object of attention of the defenders of the environment. The exhaust gases are released directly into the atmosphere, resulting in pollution. Fuel system diagnosis showed that the number of emissions if the wrong mixing increases significantly. For this simple reason, it was decided to install a catalytic Converter. However, this device showed good results only when the quality of the emulsion, and in case of any deviations, its efficiency is significantly dropped. It was decided to replace the carburetor for more precise injection system, which is the injector. The first versions consisted of a large number of mechanical components and, according to studies, this system was getting worse as the operation of the vehicle. It was quite natural, as the important nodes, and the working parts become contaminated and fail.

fuel system diagnosisIn order For the injection system are self-correcting, was created by an electronic control unit (ECU). Along with built-in lambda-probe which is located before the catalytic Converter, it gave good performance. It's safe to say that fuel prices today are quite high, and the injector is good just because it allows you to save gasoline or diesel. In addition, there are the following advantages:

  1. Increase the performance of the motor. In particular, the increased power at 5-10%.
  2. Improve dynamic parameters of the vehicle. The injector is more sensitive to changes in loads and he corrects the composition of the emulsion.
  3. The Optimum air-fuel mixture reduces the amount and toxicity of waste gases.
  4. Fuel Injection system is easy to start regardless of weather conditions, which is a significant advantage in front of carbureted engines.

Injection fuel supply system and device

First of all, it is worth noting the fact that modern fuel injected engines are equipped with nozzles the number of which is equal to the number of cylinders. Between the nozzles are connected with a ramp. There contains fuel under low pressure, and generates electric appliance – the fuel pump. The amount of injected fuel depends on duration of opening of the injector as determined by the control unit. To do this, remove the indicators from various sensors that are installed throughout the vehicle. Now we consider the main ones:

  1. The mass air flow Sensor. Is used to determine the fullness by air cylinders. In case of failure the indications are ignored and the main indicators are the table data.
  2. Sensor throttle position reflects the engine load, which is caused by throttle position, cyclic filling with air and revs the engine.
  3. Temperature Sensor hudgena. Using this controller implements the control of the blower motor and correctionfuel and ignition. In case of a failure, instant diagnosis of the fuel system optional. The temperature is taken depending on the duration of engine operation.
  4. The crankshaft position Sensor (crankshaft) are necessary for synchronization of the whole system. The controller calculates not only the engine speed but also its position in a particular point in time. As it is a polar sensor in case of a failure further operation of the vehicle is not possible.
  5. The oxygen Sensor needs to determine the % of oxygen in the vented gases. The information from this controller is sent to the control UNIT, which depending on the testimony corrects the emulsion.

Should pay attention to the fact that not all TS with an injector equipped with oxygen sensor. They are only those cars that are equipped with a catalytic Converter emission standard of “Euro-2” and “Euro-3”.pressure in the fuel system

Types of injection system: single point injection

Currently actively used by all systems. They are classified according to the number of nozzles and a place of giving of fuel. There are three injection systems:

  • Single point (the monoinjection);
  • Multi-point (distribution)
  • Direct.

First, let's consider the system of single point injection. They were created right after the carburetor and was considered to be more sophisticated, but is now gradually losing its popularity due to many reasons. There are several advantages of such systems. The main are in substantial fuel savings. Given that fuel prices today are rather big, such an injector is important. The interesting thing is that this system contains several smaller electronics, so it is more reliable and stable. When information from sensors is transmitted to the control element of the injection parameters are changed immediately. Very interesting is the fact that almost any petrol engine can be converted to the single point injection without significant structural changes. The main drawback of such systems is the low pick-up of the internal combustion engine, and the deposition of substantial amounts of fuel on the walls of the reservoir, although this problem was inherent and carbureted models.

As the atomizer in this case is only one, then it is located on the intake manifold in place of carburetor. As the atomizer was standing in a good location and was constantly under the flow of cold air, its reliability has been at the highest level, and the design was extremely simple. Flushing the fuel system with single-point injection didn't take long as it was enough to blow through only one nozzle, but increased environmental requirements led to the fact that they began to develop other, more modern system.

System multipoint injection

Injection is a more modern, complex and less reliable. In this case, each cylinder is equipped with an insulated nozzle, which is located in the intake manifold close to the intake valve. Therefore, the supply of the emulsion is conducted separately. As noted above, with this injection the power of the engine can be increased to 5-10%, which will be noticeable when driving on the road. Another interesting point: this injection system fuel is good because atomizer is very close to the intake valve. This minimizes the deposition of fuel on the walls of the reservoir, so you can achieve significant fuel savings.

injection fuel systemThere are several types of multi-point injection:

  1. Simultaneous – the opening of all injectors going on at one time.
  2. Pairwise parallel – the opening of injector pairs. One atomizer is opened in the intake stroke and the exhaust stroke. Currently this system is used only at the time of emergency start of engine in case of breakage phase (crankshaft position sensor).
  3. Phased array – each nozzle is controlled separately, and opens before the intake stroke.

In this case, the system is quite complicated and relies entirely on the accuracy of the electronics. For example, flushing the fuel system will require much more time because you have to clean each nozzle. And now let's move on and consider another popular type of injection.

Direct injection

Injection cars with such systems can be considered the most environmentally friendly. The main purpose of introducing this method of injection is to improve the quality of the mixture of fuel and a slight increase in engine efficiency of the vehicle. The main advantages of this solution are as follows:

  • A thorough spraying of the emulsion;
  • Education quality of the mixture.
  • Effective use of emulsion at various stages of engine operation.

Based on these advantages, we can say that such systems save fuel. This is especially noticeable with a quiet ride in urban environments. If you compare two cars with the same engine capacity but different injection systems, e.g. direct and multi-point shows the best dynamic performance will have a direct system. The exhaust gases are less toxic and taken liter capacity will be slightly higher due to coolingair and that the pressure in the fuel system slightly increased.valve fuel system

But should pay attention to the sensitivity of direct injection systems to fuel quality. If you take into account the standards of Russia and Ukraine, the sulfur content should be not higher than 500 mg per 1 liter of fuel. At the same time, the European standards mean content of this element 150, 50 and even 10 mg per liter of gasoline or diesel.

To briefly consider this system, it looks as follows: the injectors are in the head of the block. Accordingly, the injection is made directly into the cylinders. It is worth noting that this injection system is suitable for many petrol engines. As noted above, the use of high pressure in the fuel system under which the emulsion is fed directly into the combustion chamber, bypassing the intake manifold.

The fuel injection System on lean

A Little above we have considered direct injection, which was first used on cars, ‘Mitsubishi’, which had the acronym GDI. Let us briefly consider one of the primary modes – work with lean mixtures. Its essence lies in the fact that the vehicle in this case operates at light loads and moderate speeds up to 120 kilometers per hour. The fuel injection is carried out by the torch in the final stage of compression. Bouncing off of the piston, fuel is mixed with air and enters the zone of candle ignition. It turns out that in the cell mixture substantially depleted, however, its charge near the spark plug can be considered optimal. This is enough for its ignition then lights up and the rest of the emulsion. In fact, such a fuel injection system ensures the normal operation of the internal combustion engine even when the ratio of the air/fuel – 40:1.

This is a very effective approach, saving fuel. But you should pay attention that there was a question of neutralization of exhaust gases. The fact that the catalyst is ineffective as produces nitric oxide. In this case, the recirculation of exhaust gases. A special system allows ERG to dilute the emulsion by exhaust gases. This somewhat reduces the temperature of combustion and counteracts the formation of oxides. However, this approach does not allow to increase the load on the engine. For partial solution of the problem uses a cumulative catalyst. The latter is extremely sensitive to fuel with high sulfur content. For this reason you must periodically check the fuel system.

faulty fuel system

Homogeneous mixing and 2-stage mode

Power mode (homogeneous mixture formation) – the perfect solution for aggressive driving in urban conditions, overtaking, and traffic by highway and the highway. In this case, a conical torch, it is less economical than the previous option. The injection is carried out during the intake stroke, and the formed emulsion typically has a ratio of 14.7:1, i.e., close to stoichiometric. In fact, the system auto fuel supply is exactly the same as the distribution.

The two-stage mode includes the fuel injection on the compression stroke and start. The main task – a sharp rise of the engine. A shining example of effective work of such system is the movement at low speed and sharp pressing on the accelerator. In this case, the likelihood of detonation increases. For this reason, instead of a single stage injection takes place in two.

The first stage is injected a small amount of fuel on the intake stroke. This allows you to somewhat reduce the temperature of the air in the cylinder. We can talk about that in the cylinder will be verbena mixture in a ratio of 60:1, therefore, the detonation is impossible as such. At the final stage of the compression stroke is injected jet of fuel, which drives the emulsion to the rich in a ratio of approximately 12:1. Today we can say that the engine fuel system is introduced only for vehicles in the European market. The reason is that Japan is not inherent in the large speed, therefore, no high loads on the engine. In Europe a large number of highways and interstates, so drivers are accustomed to travel quickly, and this is a big load on the engine.

Something Else interesting

Should pay attention to the fact that, unlike carburetor systems, fuel injection requires that regular checks of the fuel system. This is because a large number of complex electronics can fail. As a result, this will lead to undesirable consequences. For example, excess air in the fuel system will lead to the violation of the composition of the emulsion and the wrong mix ratio. In the future, this affects the engine appears unstable, damaged controllers, etc. In fact, injector – is a complex system that determines when the cylinders need to spark how to deliver a quality mixture to the cylinder block or intake manifold, when to open the injectors and what is the ratio of air and gasoline should be in the emulsion. All of these factors affect the synchronized operation of the fuel system. Interestingly, a majority of controllers, the machine can work properly, thus will not besignificant deviations, as there are alarm records and tables that will be used.

perfume atomizersThe Efficiency of internal combustion engines in our case is determined by how correct will be obtained from the data controllers. Than they rather are, the less possible different faulty fuel system. An important role is played by the speed of operation of the system as a whole. Unlike carburetors there is no need for manual adjustment, and this eliminates errors during calibration work. Consequently, we get a more complete combustion of the mixture and the best from the point of view of environmental system.


In conclusion, it should tell you a little bit about the disadvantages that are inherent in fuel injection systems. The main disadvantage is the high cost of internal combustion engines. By and large, the cost of these units is higher about 15%, which is much. But there are other disadvantages. For example, defective valve of the fuel system in most cases cannot be repaired due to leakage, so it should be easy to change. This also applies to the maintainability of the equipment as a whole. Some units and parts much easier to buy new than to spend money to repair them. This quality is not inherent in the carburetor of the vehicle, where you can iterate over all the important knots and to get them running without a large investment of time and effort. Without a doubt, electronic fuel feed system repair of large forces and means. Complex electronics is unlikely to be restored on the first HUNDRED.

Well, we have talked to you about what fuel injection system. As you can see, this is a very interesting topic of conversation. You can tell a lot about what a good injector and instant adjustment of the engine. But the main points we have already said. Remember that the fuel system gasoline engine should be regularly inspected for possible defects. For example, due to the low quality of fuel that is actually inherent in our country, often clogged injector. Because of this, the engine starts to run rough, power drops, the mixture becomes too lean or Vice versa. All this is very bad for the car overall, therefore, need constant and regular monitoring. In addition, try to refuel only to those with gasoline, which advises the manufacturer of your vehicle.

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Alin Trodden - author of the article, editor
"Hi, I'm Alin Trodden. I write texts, read books, and look for impressions. And I'm not bad at telling you about it. I am always happy to participate in interesting projects."

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