Fuel supply system car spares

Fuel injection: all the information you need about part operation, installation, diagnostics, and longevity

A vehicle’s fuel system is designed to store and filter fuel, as well as supply it to the engine cylinders. Engine stability and performance depend on it.

Design of the fuel system

The fuel systems of various vehicles may differ. The main differences lie in the way the fuel is injected. Nevertheless, every vehicle has a tank to store fuel, a filter to purify it, a pump to supply it to the engine, delivery and return pipelines, and sensors which monitor, among other things, fuel level and other parameters.

Petrol vehicles may have the following types of fuel injection:

• Single-point fuel injection (SPI). A single injector supplies fuel into the inlet manifold. This is where the air-fuel mixture is formed.
• Multipoint fuel injection (MPI). There is an injector for each cylinder in the system. The fuel supply line is divided with the help of a special fuel distributor.
• Direct fuel injection. This includes a high-pressure line with another pump and a fuel rail. Fuel is supplied directly to the combustion chambers under high pressure.
• Combined fuel injection. Such fuel systems are equipped with high and low pressure fuel rails. High-pressure fuel injectors are installed into combustion chambers, while the low-pressure ones are built into the inlet manifold. The control unit selects the method of fuel supply depending on the engine operating mode.

The following types of injection systems are common in diesel vehicles:

• High pressure fuel pump. Fuel is supplied to the injectors via high pressure pump.
• Unit injectors. They ensure a layered injection of the fuel right into the combustion chambers. These components are driven by the camshaft.
• Common Rail. This encompasses a rail and a high-pressure fuel pump. The injectors are installed in the combustion chambers and are connected with the rail via a high-pressure pipeline.

Maintenance tips

• Refuel your vehicle at reliable filling stations. This will help you avoid corrosion and deposits in the fuel system, as well as to avoid the contamination of its components.
• Replace fuel filters on time. If the throughput capacity of a filter is restricted, all components of the fuel system are exposed to severe strain.
• Keep your fuel tank at least half full, especially during cold weather. Otherwise, the condensation may cause difficulties with starting the engine. Sometimes tanks begin to rust.
• Every six months, add a special additive to the fuel tank to remove moisture. This is an excellent preventive measure which will help to extend the service life of the system’s components.
• Regularly clean the injectors. In some cases, you can use a special additive for that purpose. However, it is much more effective to have them cleaned at a car repair shop.

Signs of malfunction

Difficulties when starting engine or reduced engine power can be caused by a diminished performance of the fuel pump. Engine malfunctions in every mode is a sign of a clogged filter. The same symptoms can be observed when the return pipeline is deformed, but in this case, the problem is accompanied by increased fuel consumption. The smell of petrol, coloured puddles beneath your car after parking, and significantly increased fuel consumption are symptoms of a leaky fuel system. Clogged injectors may result in engine misfiring, unusual sounds, and jerky movements while driving.

Causes of malfunction

These problems mostly occur due to fuel that is low in quality or contaminated. It contains particles which clog the filter and other system components. As a result, the pump can break down. Water is also harmful, especially, for diesel engines: The components of the fuel system are made of materials prone to corrosion. This may cause moving parts to jam. Furthermore, the throughput capacity of the injectors and pressure regulator is impaired.

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