Fuel injection system components (2023)

DieselNet Technology Guide»diesel fuel injection

DieselNet| Copyright © ECOpoint Inc. | Revision2013,06

Hannu Jääskeläinen, Magdi K. Khair


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summary: The fuel injection system can be divided into low-pressure side and high-pressure side. The low-pressure components include the fuel tank, fuel supply pump, and fuel filter. The high-pressure side components include a high-pressure pump, an accumulator, a fuel injector, and a fuel injector. Different injector designs and different actuation methods have been developed for use with different types of fuel injection systems.

  • Low-side components
    • overview
    • fuel tank and fuel supply pump
    • fuel filter
  • High-side components
    • overview
    • high pressure pump
    • Accumulator
    • fuel injector and fuel injector
    • fuel metering
    • Actuators for the nozzle needle control

Low-side components


In order for the fuel injection system to function properly, it must be supplied with fuel from the fuel tank. This is the role of the low pressure fuel system components. The low-pressure side of the fuel system consists of a number of components, including the fuel tank, one or more fuel supply pumps, and one or more fuel filters. Additionally, many fuel systems include coolers and/or heaters to better control fuel temperature. Figure 1 shows two example schematics for low-pressure fuel systems, one for a heavy-duty diesel truck and one for a light-duty diesel passenger car.[1590][1814].

fuel tank and fuel supply pump

The fuel tank is a container that holds the supply of fuel and helps maintain its temperature at a level below its flash point. The fuel tank also serves as an important means of dissipating heat from the fuel returning from the engine.[528]. The fuel tank must be corrosion-resistant and pressure-tight to at least 30 kPa. You should also use means to prevent excessive pressure build-up, such as B. a vent or safety valve.

(Video) Fuel System Components and Functions

The fuel supply pump, often referred to as the lift pump, is responsible for drawing fuel from the tank and delivering it to the high-pressure pump. Modern fuel pumps can be driven electrically or mechanically by the engine. Using an electrically powered fuel pump allows the pump to be placed anywhere in the fuel system, even inside the fuel tank. Engine driven pumps are attached to the engine. Some fuel pumps can be built into units that perform other functions. For example, the so-called tandem pumps are units that include a fuel pump and a vacuum pump for the brake booster. Some fuel systems, such as B. those based on a distributor-type pump, incorporate a mechanically driven supply pump and the high-pressure pump in a single unit.

Fuel pumps are generally sized to deliver more fuel than the engine uses on a given operating system. This additional fuel flow can serve a number of important functions, including providing additional fuel to help cool injectors, pumps and other engine components, and maintaining a more consistent fuel temperature throughout the fuel system. Additionally, excess fuel, heated by its contact with hot engine components, can be returned to the fuel tank or filter to improve vehicle operability at low temperatures.

fuel filter

Trouble-free operation of a diesel injection system is only possible with filtered fuel. Fuel filters help reduce damage and premature wear from contamination by preventing very fine particles and water from entering the fuel injection system. As shown in Figure 1, fuel systems can contain one or more stages of filtration. In many cases, a course indicator can also be found on the fuel inlet, which is located on the fuel tank.

The two-stage filter system generally uses a primary filter on the inlet side of the fuel transfer pump and a secondary filter on the outlet side. The main filter is necessary to remove larger particles. The secondary filter is necessary to withstand higher pressures and remove smaller particles that can damage engine components. Single-stage systems remove larger and smaller particles in a single filter.

(Video) Fuel Delivery System Operation

Filters can be either box-type or surrogate-type as shown in Figure 2. The box filter can be completely replaced if necessary and does not require cleaning. Replaceable element filters must be thoroughly cleaned when replacing the elements, and care must be taken not to allow residual dirt to enter the complex parts of the fuel injection system. Filters can be made of metal or plastic.

Fuel injection system components (1)

Common materials for modern fuel filter elements are synthetic fibers and/or cellulose. Microglass fiber can also be used, but due to the risk of migration of small broken pieces of glass fiber from the main element to critical fuel system components, its use is avoided in some applications.[2046]. Pleated paper, baled cotton yarn, wood chips, a mixture of baled cotton yarn and wood fibers, and rolled cotton have also been used in the past.[529].

The level of filtration required depends on the specific application. When two filters are used in series, the primary filter will generally retain particles up to about 10 to 30 µm in size, while the secondary filter can retain particles larger than 2 to 10 µm. As fuel systems evolve, clearances and stresses in high-pressure components increase, and the need for clean fuel becomes more critical. Both fuel filters are capable of meeting cleaner fuel requirements[2047]and methods for quantifying acceptable fuel contamination had to be further developed[2048].

In addition to keeping particulate matter out of the fuel supply and injection equipment, water in the fuel must also be prevented from entering critical fuel injection system components. Free water can damage fuel lubricated components in the fuel injection system. Water can also freeze in cold temperatures, and ice can block small passages in the fuel injection system, cutting off fuel flow to the rest of the fuel injection system.

(Video) How fuel injection pump works. ✔

Water can be removed from the fuel using two common approaches. The entering fuel may be subject to centrifugal forces that separate the denser water from the fuel. A much better separation efficiency can be achieved with a filter medium that separates the water. Figure 3 shows a filter using a combination of centrifugal and media type approaches.

Fuel injection system components (2)

Different water separation media work according to different principles.Hydrophobic barrier media, like siliconized cellulose, repels water and causes it to pool on the upstream surface. As the beads get larger, they run down the front of the item, forming a cup under gravity.Hydrophilic media for deep coalescencelike glass microfiber, has a great affinity for water. The water in the fuel bonds with the glass fibers and over time, as more water enters from the upstream side, massive droplets form. Water moves with the fuel through the filter and falls into a collection cup downstream of the fuel flow.

The increasing use of surface-active fuel additives and fuel components such as biodiesel has made traditional separation media less effective and filter manufacturers have had to develop new approaches such as composite media and face-to-face coalescing media[2049][2050][2051]. Methods for quantifying fuel/water separation performance were also affected.[2052].

Fuel filters may also include additional features such as fuel heaters, thermal bypass valves, breathers, water-in-fuel sensors, and filter change indicators.

(Video) Fuel Systems Explained

A fuel heater helps minimize the formation of wax crystals that can form in fuel as it cools to low temperatures. Common heating methods use electric heaters, engine coolant, or circulated fuel. Figure 1 shows two approaches using warm return fuel to warm the incoming fuel.

Fuel Spills and Leaks Fuel that spills back into the tank also carries air and fuel vapor with it. The presence of gaseous substances in fuel can cause difficulty in starting and normal engine operation in high temperature environments. Therefore, purge valves and breathers are used to remove vapors and air from the fuel supply to ensure trouble-free engine operation.



What are the three main components of the EFI system? ›

There are three components of electrical efi, ie sensors, ECU and injectors. The sensors itself, have function as detecting device, which the results serve as a reference for the ECU to determine how long the injector opens/how much gasoline spray out of the injectors.

What are the 5 components of a diesel fuel system? ›

A basic diesel fuel system is made up of five essential components. These are the tank, the fuel transfer pump, filters, the injection pump, and the injection nozzles.

What is the component that supplies fuel to injector? ›

There is a spring inside the conventional injector that holds the needle valve in close position. It holds this needle valve until high pressure line meet a specific value. There is a pipe called “fuel rail” that supplies pressurized fuel to the injectors. Right amount of fuel supplied to the required parts.

What are the 4 strokes of an EFI engine? ›

4-stroke internal combustion engine. 1:fuel injection, 2:ignition, 3:expansion(work is done), 4:exhaust.

What are the 3 types of injectors? ›

Your vehicle can be equipped with one of the three most common injection systems on the market. GDI (Direct injection), SDI (Semi-direct injection) or TBI (Throttle body injection).

What are the 8 main parts of diesel engine? ›

A medium or high speed diesel engine has such components and parts as engine body, crankshaft, connecting rod, piston, cylinder liner, heat exchanger, cylinder cover, high-pressure fuel pipe and alarm, connecting rod bolt, supercharger, fuel injection pump assembly.

What are 4 major components of a diesel engine? ›

The components of a diesel engine include pumps, mechanical pumps, high pressure pumps and common rail technology.

What is the most common fuel injection systems? ›

Manifold injection systems are common in petrol-fuelled engines such as the Otto engine and the Wankel engine. In a manifold injection system, air and fuel are mixed outside the combustion chamber so that a mixture of air and fuel is sucked into the engine.

What is the main purpose of fuel injection system? ›

Abstract: The purpose of the fuel injection system is to deliver fuel into the engine cylinders, while precisely controlling the injection timing, fuel atomization, and other parameters. The main types of injection systems include pump-line-nozzle, unit injector, and common rail.

What are the two basic parts of the fuel injector? ›

A typical fuel injector is shown in Figure , It can be seen to be two basic parts, the nozzle and the nozzle holder or body. The high-pressure fuel enters and travels down a passage in the body and then into a passage in the nozzle, ending finally in a chamber surrounding the needle valve.

What controls the fuel injection system? ›

The fuel injection system operates on the common rail principle in which timing valves, operated by cams on the camshaft, control the injection of fuel from a high-pressure manifold through spring-loaded injectors to the cylinders (Figure 14.12).

What fails in a fuel injector? ›

Fuel injectors typically fail due to a buildup of contaminants such as carbon. Carbon build-up can cause a clogged or partially clogged injector, preventing the injector from closing all the way. This results in a drip that creates a misfire.

What are the 7 modes of fuel control? ›

In this work, a single cylinder direct injection gasoline engine equipped with an electro-hydraulic valve-train system has been commissioned and used to achieve seven different operating modes, including: 4-stroke throttle-controlled SI, 4-stroke intake valve throttled SI, 4-stroke positive valve overlap SI, 4-stroke ...

What is a 3 step fuel system? ›

VPS 3-Part Plus Fuel System Kit is formulated to clean the entire fuel and air intake system including throttle plates, ports, fuel injectors, intake valves and combustion chambers. Deposits in any of these critical areas can interfere with the proper operation of your engine.

What are the 3 common types of fuel pump? ›

Mechanical, electric, and high-pressure fuel pumps are the three types of fuel pumps. A fuel pump is a fluid handling device that moves gasoline from the fuel tank to the engine. It's often found in internal combustion engines.

Is EFI the same as fuel injection? ›

EFI does exactly what it sounds like. It injects fuel directly into an engine's manifold or cylinder using electronic controls.

What are the 2 types of engine stroke? ›

Overall, a two-stroke engine contains two processes:
  • Compression stroke: The inlet port opens, the air-fuel mixture enters the chamber and the piston moves upwards compressing this mixture. ...
  • Power stroke: The heated gas exerts high pressure on the piston, the piston moves downward (expansion), waste heat is exhausted.

Which is faster 2 or 4-stroke? ›

While 4-stroke engines perform well and generally last longer than 2-stroke engines, 2-stroke engines are lighter and faster than 4-stroke engines.

What are the 5 main engine systems? ›

Important components of internal combustion engines include:
  • Fuel system.
  • Lubrication system.
  • Air intake system.
  • Exhaust system.
  • Cooling system.
  • Electrical system.
20 Feb 2018

What are the 4 stages of an engine? ›

Four-stroke cycle used in gasoline/petrol engines: intake (1), compression (2), power (3), and exhaust (4).

What are the 10 parts of engine? ›

10 most popular car engine parts that you should know
  • Engine Block. The backbone of an engine of a car is the engine block. ...
  • Pistons. A piston is a cylinder-shaped piece of metal that is inside the cylinder. ...
  • Piston Rings. ...
  • Crankshaft. ...
  • Camshaft. ...
  • Cylinder Head. ...
  • Spark plug. ...
  • Sump.
9 Aug 2022

What type of valve is a fuel injector? ›

In short, injectors are solenoid operated valves that use Pulse Width Modulated (PWM) signals from the Engine Control Unit to open or close a valve that permits or blocks fuel flow to the engine. A well designed fuel injector ensures quick and complete combustion of fuel.

What are the sizes of injectors? ›

Typically injectors come in three sizes; 34, 48 and 60mm. These measurements are taken from the top of the lower O-ring to the bottom of the upper O-ring.

What is the heart of the main engine? ›

The Combustion Chamber

The heart and lungs of the engine, where air is sucked in and combined with fuel before being tumbled, swirled, compressed, burnt and then released to exhaust. It's known as the four-stroke Otto cycle.

What are the 3 main diesel engines? ›

There are three basic size groups of diesel engines based on power—small, medium, and large. The small engines have power-output values of less than 188 kilowatts, or 252 horsepower. This is the most commonly produced diesel engine type.

What are the 3 basics components of engine? ›

In broad terms, the engine can be segregated into three key parts, the head, the block and the oil sump.
  • The cylinder head is the channel through which the fuel enters the engine chamber and exhaust gases exit. ...
  • The cylinder block is where all the combustion action takes place.

What are the 4 things an engine needs? ›

Most of these are four-stroke cycle engines, meaning four piston strokes are needed to complete a cycle. The cycle includes four distinct processes: intake, compression, combustion and power stroke, and exhaust.

What is the most important component of an engine? ›

The cylinder block is the most important component and is the basis of a car engine. The main function is to accommodate the crankshaft mechanism. Inside the cylinder block, you can find several engine cylinders, each of which is connected to the piston and crankshaft at the other end of the road.

What is the main component in diesel? ›

Diesel fuel consists mainly of paraffins, aromatics and naphthenes. The hydrocarbons of gasoline contain typically 4-12 carbon atoms with boiling range between 30 and 210 °C, whereas diesel fuel contains hydrocarbons with approximately 12–20 carbon atoms and the boiling range is between 170 and 360 °C.

What is the correct order of fuel injection? ›

Explanation: The fuel flows from the fuel tank to the feed pump where the pressure is increased and then the fuel is filtered by the filter and then it is sent to the injector. Therefore the correct sequence of the fuel flow is fuel tank – feed pump – filer – injector.

What controls the fuel injector pulse? ›

A fuel injector firing

The amount of fuel supplied to the engine is determined by the amount of time the fuel injector stays open. This is called the pulse width, and it is controlled by the ECU.

What is the pressure of fuel injector? ›

It is between 35 and 65 pounds per square inch (psi) on most vehicles.

What are three types of fuel injection systems? ›

Your vehicle can be equipped with one of the three most common injection systems on the market. GDI (Direct injection), SDI (Semi-direct injection) or TBI (Throttle body injection).

What are the major components of fuel oil system? ›

The system basically consists of settling tanks, suction and discharge strainers, pumps, heating coils, seven valves to properly meter fuel and other assorted hardware. The four settling tanks are located in the after portion of the engine room.

How does a fuel injection system work? ›

A modern fuel injection system works by atomising the fuel at high pressure, mixing it with clean air as it passes the inlet manifold, before entering the combustion chamber of each cylinder. The key element of the electronic modern fuel injection system is the word “electronic.”

What are the two types of fuel pumps? ›

There are two types of mechanical fuel pumps: diaphragm-type fuel pumps and plunger-type fuel pumps.

What are the 6 fuel system delivery components? ›

The low-pressure components include the fuel tank, fuel supply pump and fuel filter. The high-pressure side components include a high pressure pump, accumulator, fuel injector and fuel injector nozzle.

What are the 3 types of fuel oil? ›

Fuel oil is used for different things and is known by different names such as: Diesel fuel. Kerosene oil. Furnace oil.

What are the 4 components of oil? ›

Constituents of crude oil. Hydrocarbons are generally divided into four groups: (1) paraffins, (2) olefins, (3) naphthenes, and (4) aromatics (Figure 1.8). Among these groups, paraffins, olefins, and naphthenes are sometimes called aliphatic compounds, as different from aromatic compounds.


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