An important element of the design of any modern is the fuel pump (TN), which submits to the carburetor or to the nozzles the required fuel.
Electric fuel pump - general information about it
All TN, which are currently exploited, divide on:
- electrical;
- mechanical.
The electric unit is used in diesel engines, as well as in gasoline, on which the combustible injection system is implemented.
In this case, the mechanism described by us is necessary in order to supply (pre-) gasoline to the TNVD (high pressure pump). Mechanical type pumps are not suitable for this because they are able to ensure a fuel supply exclusively at low pressure. But the electric pumping fuel pump can form pressure up to 0.7 MPa in systems with direct injection and up to 0.4 MPa for diesel engine.
Many not very experienced motorists are asked about where the fuel pump is located. The answer is simple. This device is located either in the fuel tank itself or in the fuel line. Experts consider the first type of layout (TN embedded in the tank). It is believed that with such a placement that does not require a special suction highway, the risk of fuel loss is minimal. At the same time, the pump is much better and faster, and its filter operates with one hundred percent return.
If you look at the design of the fuel system of modern foreign cars, you can see that on many of them the fuel pump is really integrated into the tank. True, with the described layout, the discharge fuel line becomes more prone to breakdowns and outputs due to its high length.
In general, we figured out where the fuel pump is located on the vehicles of our days. And now let's look at the design of this unit. Such a device consists of two main components located in one case made of metal - directly pump and electric motor (drive). It also has additional elements - a fuel fence mechanism, a mesh filter, a combustible consumption sensor, valves (reduction and intricate).
All components of the electric pump, including the filter, are constantly in contact with flammable, but when the system is functioning, the probability of a short circuit in it is reduced to zero, since the electrical resistant indicator of gasoline is at a high level (above 1m). For maintenance of the required pressure in the fuel system of the vehicle, the reduction valve is responsible. And when the engine is stopped, the fuel system is locked (it contains the check valve in it).
Different types of electrical pumps and their features
Constructive electrical TN can be:
- centrifugal;
- gear;
- roller.
Directly into the fuel tank is usually mounted centrifugal electric unit. The fuel pump relay of this type is activated by "order", which sends a diesel or gasoline engine control unit, and the electric pump begins to work. Note that in the design of the device described, there is a safety special chamber, which supports fuel pressure in fairly narrow intervals.
Repair such a TN is needed very rarely. Replacements usually requires an impeller - a working device equipped with a large number of blades. This component rotates in the chamber with the injection and suction channel. Increasing the pressure of the diesel (carburetor) engine at the same time, it is formed when the specified blades are influenced by fuel.
In roller TN, the suction of fuel and its injection is achieved by rotating the rotor, in which the rollers movement. Similarly, the gear pump of diesel car (gasoline) works. Only in it the inner gears rotate around the stator. Roller and gear electric TN can only be mounted in the fuel line.
Features of the mechanical pump, its device
This low-pressure fuel pump is not suitable for a diesel engine. It is used only on carburetor machines. Place it on the motor itself, the device is made of the following parts (to the repair of which, we note, is not so rarely required):
- housing with the upper and lower part;
- cover covering housing;
- mesh;
- diaphragm (located between the parts of the case);
- mechanical drive (without it the device to work, as you understand, can not);
- stock;
- two valves (injection and suction);
- hope for rod spring (return).
The drive, which is equipped with a mechanical low-pressure fuel pump, is performed from camshaft (from its eccentric). And the most important element of the mechanism is the diaphragm connected to the drive and a rod. On imported car, the actuator scheme is implemented, as a rule, with a rocker (with a special lever having two shoulders). Russian automotors usually use a scheme that includes a lever with a balance and pusher.
How to check the fuel pump?
Signs that TN functions incorrectly, not so noticeable as drivers would like. But, nevertheless, they are. The following are the main features that are a signal of what makes sense to check the fuel pump of its gasoline or diesel engine:
- Difficulties with the launch of the motor. Perhaps the fault of the fuel pump relay, starter, and maybe it's only a small charge of the battery. But, in any case, the reason to identify will have. It is likely that she will tell you exactly about the fault of the fuel pump.
- ignition turns off;
- the high pressure fuel line is disconnected;
- include ignition provided that there are no flows of fuel;
- after that, the fuel pump relay is examined (in most cases, the subsequent removal and installation of the fuel pump is not needed, as it is only required to replace its fuse).
- In cases where, after replacing the fuse, there is a voltage supply, the problem is most likely in the cable break (it is less likely to fully repair and replacing the fuel pump) due to the fact that the device failed. If fuel does not come to the pipeline (distribution), there is a danger that the fuel line was damaged or a fuel filter (fuel pump grid) was clogged.
Scheme of the performance of the performance of TN and possible repair for which the fuel pump cover puller may be required:
