In most cases, the fuel pump is mounted next to the tank, although there are designs where it is built directly into the tank itself. A fuel filter is installed between the pump and the injectors, which is responsible for the cleanliness of the fuel. Its main task is to trap foreign particles and contaminants that can enter the tank from the environment.
When the pressure in the fuel line becomes higher than permissible, excess fuel is directed back into the tank through return lines. This mechanism maintains stable operation of the system, prevents pressure surges, and protects its components from damage.
Failure of the electric pump or its unstable operation usually results in costly repairs or complete replacement of the unit. Today, you can buy a fuel pump through online auto parts stores, choosing the part by the car's VIN code.
There are two main types of fuel pumps: mechanical and electric. Mechanical units operate via drive belts from the engine, while electric ones operate thanks to the electronic injection system. The latter are usually characterized by higher reliability and fewer problems during use.
Cars with a carburetor are typically equipped with a mechanical diaphragm pump. Such a device is driven by the camshaft, draws fuel from the tank, and delivers it to the carburetor's float chamber. The working pressure in this case ranges from 0.2 to 0.3 bar.
The electric pump is considered more reliable than the mechanical one. Its design includes the following elements:
- A cover with electrical connectors, a check valve (prevents fuel leakage), and a hydraulic outlet. It also houses carbon brushes for the commutator motor and interference protection elements — inductors and capacitors if needed.
- An electric motor consisting of an armature and permanent magnets. A copper commutator is usually used, while carbon commutators are used for special systems and diesel units.
- A pump section, which can be positive displacement or flow-through.
- Electric fuel pumps are divided into flow-through and positive displacement types.
Pressure pumps are noted for their reliability and safety, as they operate continuously and almost without pulsation. They can be combined with higher-capacity pumps, regardless of the operating mode and maximum load.
Booster pumps are used for working with viscous media, such as cold diesel fuel. Depending on the design and operating conditions, significant pressure pulsation is possible. For correct operation of electric pumps in gasoline injection systems, the pressure stage was separated from the main pump. Thanks to increased pressure effort and resistance to vibrations, such pumps have found application in general-purpose diesel systems. Powerful pumps can create pressure up to 6.5 bar.
In electronic gasoline injection systems, electric pressure pumps were initially placed outside the tank — in the line. Later, the design changed: the pump became part of the fuel delivery module, which may also include other components. Among them are the fuel level sensor and the pump's protective filter.
The advent of injection systems in modern engines necessitated electric fuel pumps. Regardless of the engine temperature, the electric pump (high-pressure fuel pump) ensures the supply of the required amount of fuel at the pressure needed for injection.
Safety
A damaged electric fuel pump that does not perform its functions can negatively affect driving safety and comfort. Insufficient fuel supply leads to unstable engine operation, including misfires and deformations.
One of the key advantages of an electric fuel pump is more economical fuel consumption, as it has no mechanical drive and associated resistance. Disconnecting the pump from the mechanical part of the engine also allows more precise control of fuel delivery. For example, pre-delivery of fuel for quick engine start is possible, which is especially relevant for "stop-start" systems.
