You can find and buy High Pressure Fuel Pump / Fuel Injection Pump of high High Pressure Fuel Pump / Fuel Injection Pump – HYUNDAI H Box D (57 . The last carburetor-equipped car came off the assembly line in Since then, fuel injectors have been the primary means of getting gasoline into the engine. For the engine to run smoothly and efficiently it needs to be provided with the right quantity of fuel/air mixture according to its wide range of demands.

Author: Gardajinn Tygolkis
Country: Zimbabwe
Language: English (Spanish)
Genre: Sex
Published (Last): 17 November 2018
Pages: 217
PDF File Size: 17.61 Mb
ePub File Size: 13.25 Mb
ISBN: 613-2-43791-239-5
Downloads: 13516
Price: Free* [*Free Regsitration Required]
Uploader: Tazilkree

Petrol-engined cars use indirect fuel injection. A fuel pump sends the petrol to the engine bay, and it is r57 injected into the inlet manifold by an injector. There is either a separate injector for each cylinder or one or two injectors into the inlet manifold. One solution is to fit twin-carburettors, but these are difficult to tune correctly. Instead, many cars are now being fitted with fuel-injected engines where the fuel is delivered in precise bursts.

Engines so equipped are usually more efficient and more powerful than carburetted ones, and they can also be more economical, as well as having less poisonous emissions.

Direct Injection Basics | HowStuffWorks

The fjel injection system in petrolengined cars is always indirect, petrol being injected into the inlet manifold or inlet port rather than directly into the combustion chambers. This ensures that the fuel is well mixed with the air before it enters the chamber. Many diesel engineshowever, use direct injection in which the diesel is injected directly into the cylinder filled with compressed air.

Others use indirect injection in which the diesel fuel is injected into innection specially shaped pre-combustion chamber which has a narrow passage connecting it to the cylinder head.

Only air is drawn into the cylinder. It is heated so much by compression that atomized fuel injected at the end of the compression stroke self-ignites.

All modern petrol injection systems use indirect injection. A special pump sends the fuel under pressure from the fuel tank to the engine bay where, still under pressure, it is distributed individually to each cylinder. Depending on the particular system, the fuel is fired into either the inlet manifold or the inlet port via an injector. This works much like the spray nozzle of a hoseensuring that the fuel comes out as a fine mist.

Some cars have multi-point fuel injection where each cylinder is fed by its own injector.

How a fuel injection system works | How a Car Works

This is complex and can be expensive. It’s more common to have single-point injection where a single injector feeds all the cylinders, or to have one injector to every two cylinders. The injectors through which the fuel is sprayed are screwed, nozzle-first, into either the inlet manifold or the cylinder head and are angled so that the spray of fuel is fired towards the inlet valve.

The injectors are one of two types, depending on the injection system. The first system uses continuous injection where iniection fuel is squirted into the inlet port innection the time the engine is running.


The injector simply acts as a spray nozzle to break up the fuel into a fine spray – it doesn’t actually control the fuel flow. The amount of fuel sprayed is increased or decreased by a mechanical or electrical control unit – in other words, it is just like turning a tap on and off. The other popular system is timed injection pulsed injection where the fuel is delivered in bursts to coincide with the induction stroke of the cylinder.

As with continuous injection, timed injection can also be controlled either mechanically or electronically. The earliest systems were mechanically controlled. They are often called petrol injection PI for short and the fuel flow is controlled by a mechanical regulator assembly.

These systems suffer from the drawbacks of inection mechanically complex and having poor response to backing off the throttle. Mechanical systems have now been largely superseded by electronic fuel injection known as EFi for short.

This is thanks to the increasing reliability and decreasing costs of electronic control systems. In the Lucas system, fuel from the tank is pumped at high pressure to a fuel accumulator.

From there it passes into the fuel distributor, which sends a burst of fuel to each injector, from where it is fired into the inlet port. The airflow is controlled by a flap valve which opens in response to the accelerator pedal. For cold starting, a choke on the dash or, on later models, a microprocessor control unit brings a special cold-start injector into operation, which injects extra fuel to create a richer mixture.

Once the engine has fueel up to a certain temperature, a thermoswitch automatically cuts off the cold-start injector. Mechanical fuel injection was used in the s and s by many manufacturers on their higher-performance sports cars and sports saloons.

A high-pressure electric fuel pump mounted near the fuel tank pumps fuel at a pressure of psi injectioon to a fuel accumulator. This is injecyion a short-term reservoir that keeps the fuel-supply pressure constant and also irons out the pulses of fuel coming up from the pump. From the accumulatorthe fuel passes through a paper element filter and then feeds into the fuel-metering control unit, also known as the fuel distributor.

This unit is driven from the camshaft and its job, as the name suggests, is to distribute the fuel to each cylinder, at the correct time and in the correct amounts.

Diesel fuel injector for Citroen Saxo 1.5 D, 57 hp, 5 doors, 1999

The amount of fuel injected is controlled by a flap valve located in the engine’s air intake. The flap sits beneath the control unit and rises and falls in response to airflow – as you open the throttle, the ‘suck’ from injectiln cylinders increases the airflow and the flap rises. This alters the position of a shuttle valve within the metering control unit to allow more fuel to be squirted into the cylinders.

From the metering unit, the fuel is delivered to each of the injectors in turn. The fuel then squirts out into the inlet port innection the cylinder head.

D75 injector contains a spring-loaded valve that is kept closed by its spring pressure. The valve only opens when the fuel is squirted in. Instead a manual control on the dash resembling a choke knob or, on later models, a microprocessor alters the position of v57 shuttle valve within the metering unit. This activates an extra injector mounted in the manifold, causing it to squirt in extra fuel to enrich the mixture. An electronic system is operated entirely by a microprocessor control unit. The main difference between electronic injection and mechanical injection is that an electronic system is controlled by a complex microprocessor control unit sometimes called an electronic control unit or ECUwhich is basically a miniature computer.


This computer is fed with information from sensors mounted on the engine. These measure factors such as the air pressure and temperature in the air intake, the engine temperature, accelerator position and injecgion speed.

All this information allows an electronic system to meter the fuel far more accurately than the simple mechanical system, which relies on sensing the airflow alone. The computer compares the input signals from the sensors with information already programmed into it at the factory, and works out exactly how much fuel should be delivered to the engine.

It then signals the on-off valve ig the injector to open and squirt fuel into the inlet port. All this happens in a fraction of a second, the control unit responding instantly to changes in accelerator position, temperature and air pressure.

As well as improved control over fuel flow, the electronic system also operates at lower pressure than a mechanical system – usually at around psi. This makes it run more quietly than a mechanical system does. A typical system is the Bosch LJetronic, which is fitted to a wide range of European cars.

In this system, fuel is drawn from the tank by an electric pump. It is then fed straight up pipes to the injectors.

The system pumps more fuel than is needed injectino injection – a loop circuit returns the excess to the fuel tank via a pressure regulator which keeps the pressure in the pipes constant. The injector valves are held closed f57 springs, and opened by solenoids electromagnets when signalled to do so by the control unit.

The amount of fuel injected depends on how long the solenoid holds the injector open. A fuel injection system Fuel pump Fuel filter Fuel accumulator Fuel distributor Inlet tract Inlet manifold Injectors Cold-start injector Pip from petrol tank Return pipe to tank A fuel injection system Petrol-engined cars use indirect fuel injection.

Stop wasting time on YouTube and get serious! The Ultimate 20 hour car mechanics video course Learn everything about modern cars from our new video series.

Every part explained There’s ridiculous detail on every part. Clearly and easily explained. All modeled in 3D We’ve created the most detailed 3D model ever produced so we can show you everything working. Read more essential guides Servicing a mechanical fuel pump Do not clamp a pump in a vi How car oil is refined The fuel used in a modern c