What is a gas pump for a car and how it works


The gas pump is an important part of the car, without which it is impossible to supply fuel to the engine cylinders and, of course, to ignite the air-fuel mixture to set the piston group in motion. Every motorist should understand how different parts of a car work. This is necessary in order to understand what to do if the car does not want to start, or stalls while driving.

Where is the fuel pump located?

The location of the fuel pump depends on the car model. In the classic with a longitudinal engine, this mechanism can be installed near the crankshaft. Models with a transverse engine can be equipped with a mechanical pump that is installed in the area of ​​the camshaft. This is a common position of mechanical modifications.

What is a gas pump for a car and how it works

As for the electric options that are used in injection vehicles, their design is more complex than that of the mechanical counterpart. During operation, such a pump makes a decent noise. In addition to noise and vibration, the electrical modification gets very hot.

For these reasons, engineers at most automakers have placed this mechanism directly in the fuel tank. Thanks to this, the operation of the fuel pump is practically inaudible and at the same time it is properly cooled.

Purpose and principle of operation of the fuel pump

What is a gas pump for a car and how it works

The name of the device itself speaks of its purpose. The pump pumps fuel from the reservoir to the carburetor or through the injectors directly into the cylinders themselves. The principle of work of a part does not depend on its size and model.

Every modern internal combustion engine is equipped with an electric fuel pump. How does it work?

How does an electric petrol pump work

Electric models work on this principle. A signal is received from the on-board computer, and the pump begins to pump gasoline into the line. If the engine does not start, the ECU turns off the device so that it does not burn out.

While the engine is running, the control unit monitors the throttle position and fuel flow rate. The computer also changes the speed of the pump impeller to increase or decrease the amount of fuel being transported.

What does an electric petrol pump consist of?

What is a gas pump for a car and how it works

Electric fuel pumps consist of:

  • electric motor;
  • hydraulic blower.

An electric motor is needed so that the fuel supply does not depend on the speed of rotation of the car engine, as in mechanical modifications.

The second unit consists of a safety valve (relieves excess pressure) and a check valve (does not allow gasoline to return back to the tank).

Types of gas pumps and how they work

All fuel pumps are divided into two types:

  • mechanical;
  • electric.

Although the main purpose of the devices remains the same, they differ from each other in the principle of operation.

Mechanical type

What is a gas pump for a car and how it works

This category of gasoline pumps is used on carburetor engines. They are installed in close proximity to the motor, as they are driven by rotation camshaft (on front-wheel drive cars, the camshaft is equipped with an eccentric that drives the pump lever pusher) or the rotation of the oil pump drive (rear-wheel drive cars).

These pumps have a simple design. Inside them is a spring-loaded diaphragm. In the center, it is attached to a rod that abuts against the drive arm. There are two valves in the upper part of the body. One works to get gasoline into the chamber, the other to get out of it. The amount of fuel supplied to the carburetor depends on the space above the pump diaphragm.

The camshaft eccentric (or, in the case of rear-wheel drive cars, the cam of the oil pump drive) drives the pusher, which, using a lever, changes the position of the membrane. When the eccentric moves, the diaphragm is lowered and a vacuum is created in the pump vessel. As a result, the inlet valve is activated and gasoline enters the chamber.

The next movement of the cam cam allows the spring loaded diaphragm to return to its place. This builds up pressure in the chamber, and fuel flows through the exhaust valve to the carburetor.

Electric fuel pump and their types

What is a gas pump for a car and how it works

Electric fuel pumps are installed on injection type motors. In this case, the fuel must be supplied under pressure, so mechanical models are useless here.

Such pumps can already be located in different parts of the fuel line, since they are already powered by electricity. Among all models, there are three main types:

  1. roller;
  2. centrifugal;
  3. gear.

1) Rotary roller pumps are installed anywhere in the fuel line. They work on the principle of moving rollers inside the blower. The rotor of the electric motor is located with a slight offset in relation to the roller in the blower chamber.

When the rotor rotates, the roller is displaced, from which a vacuum is created in the cavity. The fuel flows into the pump through the inlet valve. As the roller moves, gasoline exits the cavity through the exhaust valve.

What is a gas pump for a car and how it works

2) Centrifugal models are always installed inside the gas tank. An impeller is installed on the electric motor shaft. It rotates inside the container of the blower. The turbulence of the fuel in the chamber is created from the speed of rotation of the blades. Then, through the exhaust valve, gasoline enters the fuel line, where the required pressure is created.

What is a gas pump for a car and how it works

3) This type of gasoline pump also works by rotating the shaft with an offset axis. A gear is fixed to the rotor, which is located inside the secondary gear. Fuel enters the part chamber due to the movement of the gears.

What is a gas pump for a car and how it works

Most vehicles are equipped with centrifugal pumps. They provide a smoother flow of gasoline and are easy to manufacture.

The main malfunctions of the fuel pump

Due to the simple design, electric pump models have a long service life. And mechanical ones practically do not break. Most often, the membrane, or the spring located under it, fails in them.

What is a gas pump for a car and how it works

Here are the main malfunctions of electric fuel pumps:

  • Overheating of the electric motor due to frequent driving with a low fuel level in the tank.
  • Oxidation of contacts, or damage to electrical wiring.
  • Clogged filter.
  • Wear of moving parts.

The serviceability of fuel pumps is checked as follows.

  1. Mechanical. The top cover is removed and the condition of the diaphragm is checked. To test it in action, you need to disconnect the hose from the carburetor and start the engine. If the jet is flowing evenly and with good pressure, then it is working correctly.
  2. Electrical. Their serviceability is checked even easier. When the car ignition is turned on (turning the key one position), the diagnostic lights come on. At this moment, the fuel pump should start working. The driver should hear a low buzz for 1-1,5 seconds. If this sound is not heard, then something has happened to the pump.

Most often, breakdowns of fuel pumps are eliminated by their complete replacement. In the event of a membrane failure in mechanical models, it can be replaced with a new one by purchasing a fuel pump repair kit in the store.

How to put an electric gas pump on a carburetor engine, see the video:

Electric gas pump for carburetor Correct setting of HEP-02A

Service life of the fuel pump

The service life of a fuel pump depends on its design and the materials from which it is made. Depending on the model of the device, the fuel pump will work without interruptions in the interval from 100 to 200 thousand kilometers of the car.

The pump fails for two main reasons:

  • untimely replacement of fuel filters. Moreover, some pay attention only to the fine cleaning element, but the cleanliness of the mesh, which is installed directly on the pump itself, deserves no less attention. When the pump tries to build up pressure through a dirty filter, it gets hotter. Timely maintenance will extend the pump life;
  • the fuel tank is often low on fuel. Because of this, the device does not receive adequate cooling, so the risk of overheating increases significantly.

Also pay attention to the video on how you can restore some pumps:

Types of breakdowns of fuel pumps in an injection car


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