Car & Van Fuel Injection System

Everyone knows that a car needs fuel in order to run, but have you ever considered how it gets from your fuel tank to the engine? If the engine is the heart of the car, the fuel injection system makes up the veins that supply the fuel. The combination of air and diesel or petrol needs to be carefully controlled in order to ensure your engine works efficiently and cleanly. This is the job of the fuel injection system, and there have been major changes in the way it operates in the last few years. Whichever fuel injection system your vehicle uses, you can’t drive without one so if you are encountering problems you will need to get it put right quickly with the help of experts from the AutoMend network.

You have a great choice and at the best prices – you can pick any of our participating garages and mobile mechanics to take a look at your fuel injection system. Covering every part of the UK, we are never far away whether you are stranded at the roadside, stuck at home with a car or van that just won’t start, or looking to book your vehicle in for a service. Simply tell us the make of your vehicle and the service you are looking for. Next, we need to know your location (usually your post code or nearest town), and we can then give you a list of local contacts. We include useful information such as how far from you the mechanics are located, and all their details so you can get in touch directly with them if you wish. If you would rather get an online quote first, you can ask for as many as you like, free of charge and with no obligation. We are confident that our trusted industry-approved mechanics will be able to solve your fuel injection problems and get your engine running smoothly again. Don’t waste your valuable time searching the net for fuel injection system repairs, contact an AutoMend network member today.


For a smooth-running and efficient engine, you need just the right amount of fuel and air at just the right pressure to be supplied to the cylinders for combustion. You not only need the correct proportions to be delivered, you also need it to be delivered at the same rate to all the cylinders at the same time. Modern fuel injection systems are instrumental in delivering just what the engine needs, when it needs it.

In petrol engines, the fuel injection system is an indirect one. The petrol is pumped into the engine bay, to be injected into an inlet manifold instead of going immediately into the combustion chamber. The reason for the indirect injection is to make sure that the petrol has the chance to fully mix with air before being sent into the combustion chamber. Some petrol engines have a single or a double injector which serves the inlet manifold, and some engines have a single injector for each individual cylinder.

A large number of diesel engines operate via direct injection – the fuel goes straight into the cylinder, which is full of compressed air.

Other diesel engines have the fuel injected into a pre-combustion chamber, then through a narrow outlet into the cylinder-head. The compression within the cylinder produces the heat that makes the diesel fuel self-ignite at the end of each compression stroke.


The fuel injection system is complex with many different parts, both mechanical and electronic, so here are some symptoms to look out for, along with some suggested causes:

The engine power is not consistent or is running unevenly upon idling – a dirty fuel injector may be causing an inconsistent fuel supply. You may see the engine revving high or low, or if you have an RPM gauge, it may show fluctuations.

The engine is misfiring – a clogged or dirty fuel injector may be failing to open, causing a lack of fuel on ignition. A small reduction in the performance of a single injector can cause this problem.
There is a smell of fuel – a leaking or clogged fuel injector could be the cause.

The fuel consumption (miles per gallon) has deteriorated – a leaky or clogged fuel injector cannot deliver the required fine mist of fuel and air, resulting in droplets of fuel in the combustion chamber. The droplets will burn inefficiently and cause you to use more fuel than usual.


Fuel injection systems have been around in some form or another since the 1950s. However, up to the 1980s, the supply of the essential fuel and air mixture to the engine was done by a carburettor in almost all production cars. The carburettor works by using the pressure created during one of the phases of the engine’s ignition process – the fuel is literally sucked into the combustion chamber.

One of the problems with a carburettor on a multi-cylinder engine is that some of the cylinders are sited further away from the source of fuel and air than others. This means that it is nearly impossible for a single carburettor to supply each cylinder with precisely the same amount of the fuel and air mix, resulting in poor engine performance.

To get around this problem of supply, some engines were designed with paired or twin carburettors. However, these are difficult to tune up and keep in tune.

Carburettors were seen as inefficient, and fell out of favour, with all production cars moving over to either mechanical or electronic fuel injection systems. Fuel injected engines are not only more fuel-efficient and powerful than those with a carburettor, they also emit fewer poisonous fumes and dangerous particles into the environment.


Once carburettors had gone out of favour, many manufacturers moved to mechanical fuel injection systems. These systems were really only a cut above the carburettor in that they needed careful setting up and regular tuning to work at their best. They utilised mechanical systems to measure the fuel and air mixture, and then injectors to inject it into the engine. Improved metering and measurement, combined with the injection of the atomised fuel and air mix did give an improvement in engine performance and efficiency, but fuel injection really came into its own with the introduction of electronic fuel injection systems.


Controlled by the Electronic Control Unit (ECU), electronic fuel injection systems give precise control of the amount of fuel injected into the cylinders. Here’s an overview of how a typical system operates:

The fuel pump moves fuel from the tank along the fuel lines in the direction of the engine. The flow of fuel is controlled by a fuel pressure regulator, which allows a certain volume of fuel to get to the injectors. The fuel pressure regulator is alerted to the required volume of fuel by the MAF (mass airflow sensor) which monitors the airflow into the engine. The required ratio of fuel to air is calculated by the ECU. The atomised gas (air and fuel mixture) is then injected into the appropriate part of the engine for combustion.

Vehicle engine technology is constantly changing and evolving, and today’s fuel injection systems would have seemed miraculous to motorists of previous generations. They are fuel-efficient and clean-running, releasing ever smaller amounts of pollutants and dangerous particles into the atmosphere. However, the technology is only as good as the care and maintenance it receives. Don’t risk a breakdown due to a faulty or inefficient fuel injection system – get it checked and tested out by a member of the AutoMend network of car and van garages and mobile mechanics. They are fully-qualified and capable of working to the highest standards, and they are committed to providing timely, value for money services.