5.2. System of injection of fuel
Elements of system of injection of fuel
The fuel pump shipped in the fuel tank gives fuel to the fuel highway via the fuel filter. Fuel pressure in system is run by pressure regulator. It allows excess fuel to come back to the fuel tank at excess of pressure in system. The fuel highway is the tank for nozzles which inject fuel into inlet channels of cylinders of the engine. The block operates work of a nozzle, changing impulse duration – an interval of time during which the nozzle is open to provide supply of richer or poorer gas mixture.
The throttle knot of system of injection of fuel is located on an inlet collector where the carburetor usually settles down.
Pipelines of giving and return of fuel
When replacing pipelines of giving and return of fuel always use steel welded pipes. For ensuring tightness of connection of the fuel pipeline the new pipe has to be the same type, as well as earlier established on the car.
Do not use copper or aluminum tubes instead of the steel tubes established on the car as they cannot sustain vibration at operation of the car.
Always replace sealing rings and laying if their state causes suspicion.
Metal fuel tubes are laid under the bottom of the car and fixed by clips and the self-cutting screws. They need to be examined periodically on lack of leaks and damages.
When replacing pipelines, the new pipeline needs to be laid on the same way, as earlier established.
For prevention of wiping of pipelines they have to be reliably attached to a car body.
For prevention of wiping of pipelines because of contact with other details it is necessary to provide the gap equal to, at least, 6 mm around the pipeline.
Flexible fuel hoses are made especially for giving and return of fuel. At emergence of need of replacement of these hoses replace them only with hoses of the same type.
Flexible fuel hoses have to settle down at distance not less than 100 mm from elements of system of production of the fulfilled gases and 250 mm from catalytic converter.
The electric fuel pump, the fuel level sensor and the regulator of pressure are located in the fuel tank (fig. 5.1).
The fuel tank has a branch pipe for the line of return of fuel. Fuel mix and hot fuel come back to a tank on the separate pipeline. Continuous circulation of fuel via the fuel pump reduces possibility of air traffic jams in the fuel pipeline.
Relay of the fuel pump
For management of operation of the fuel pump the relay of the fuel pump is used.
When the ignition key is turned in situation "Run" (Work), the relay of the fuel pump turns on the pump on 1,5–2,0 with for creation of pressure in fuel system and its giving under pressure to throttle knot. If after that impulses from the ignition distributor do not come to an electronic control unit, the block gives a relay signal for shutdown of the fuel pump. The relay will turn on again the pump when the electronic control unit receives impulses from the ignition distributor.
The fuel tank settles down under the bottom of the car and depending on model has various volume and the form.
The tank fastens two collars on the loops (fastening bolts). The opposite end of a collar fastens a bolt and a nut.
For prevention of knocks and other extraneous noises from above of the fuel tank noise-attenuating elements are established. It is necessary to examine the fuel tank, a stopper of a toplivonalivny mouth and fuel pipelines on existence of the possible leak of fuel arising because of their damages at movement along roads with an uneven covering. Examine a mouth stopper on existence of tightness and absence of damage. Replace all damaged or faulty details.
Before starting works on service of the fuel tank, perform the following preparatory operations:
– disconnect a wire from the negative plug of the rechargeable battery;
– establish the sign "Not Smoke" in a working zone;
– be convinced available the carbon dioxide fire extinguisher;
– put on goggles;
– merge or pump out fuel from the fuel tank in explosion-proof capacity.
The mouth of the fuel tank has the screw-on stopper. For removal of a stopper from a mouth it is required to turn it several times counterclockwise. The long site of a carving allows to pit gradually excessive pressure during a stopper otvorachivaniye.
The built-in safety mechanism does not allow to wrap a stopper too strongly. For a wraparound of a stopper turn it until clicks become heard. It means that the necessary moment of tightening is reached, and the stopper is completely screwed.
In need of replacement of a stopper of a toplivonalivny mouth apply a stopper only with the same characteristics. Non-compliance with this rule can lead to serious violations of work of fuel system.
Fuel level sensor
Fig. 5.2. A canister of catching of vapors of fuel with absorbent carbon (1) and a hose of return of fuel (2)
The fuel level sensor fastens bolts to the lower forward surface of the fuel tank and has laying between it and the case of a tank. The line of return of vapors of fuel is connected to a branch pipe of ventilation of the fuel tank and a canister for catching of vapors of fuel (fig. 5.2). Fuel moves the fuel pump located in the top part of the fuel tank and comes back via the fuel level sensor in the lower forward part of the fuel tank.