When looking for a possible cause of insufficient power and poor responsiveness of the car, it is necessary to inspect again: the ignition system (breaker-distributor, high-voltage wires, spark plugs); fuel pump, since its unstable operation does not allow the engine to develop the maximum crankshaft speed; fuel poured into the fuel tank (demanding maximum power from the engine when filled with low-octane fuel is pointless); air filter (clogged and oily it will become an obstacle to incoming air); carburetor, which in most cases (on cars 1-3 years old) turns out to be the number one culprit (you should pay attention to the fuel level in the float chamber of the carburetor, since in this case the level will be lowered); condition (cleanliness) of the main jets; accelerator pump performance; engine operating temperature range.
The accelerator pump (Fig. 45) serves to temporarily enrich the combustible mixture when the throttle valve is opened sharply, which improves the car's responsiveness. Lever 6 has an unusual configuration, but this is not the designer's fantasy, but an accurate calculation. The accelerator pump must supply both chambers with fuel (primary and secondary) carburetor. This is achieved by the intricate profile of lever 6. Thanks to it, the pump performs a second injection at the moment when the throttle valve of the secondary chamber opens. When the fuel supply control pedal is pressed, lever 7 of the accelerator pump actuates diaphragm 10, which, overcoming the resistance of spring 8, pushes fuel out of cavity 9 into channel 3 and through ball valve-screw 1 and sprayer 2 - into the diffuser of the primary carburetor chamber. Valve I is closed. If a sharp increase in power is not required and smooth pressure is exerted on the diaphragm, then with the help of jet 4 all the fuel displaced by the diaphragm enters float chamber 5, which ensures the stability of the required engine operating mode. A special chamber 12 is allocated for the vapors formed in the cavity of the accelerator pump.
Checking the accelerator pump's performance usually begins with an external inspection. It is important to make sure that gasoline does not leak from under the pump cover. If it leaks, it suggests that the diaphragm is faulty. Then you can check the pump's performance. It is enough to remove the air cleaner cover and turn lever 6. A full and even stream of gasoline from sprayer 2 will dispel all concerns about the accelerator pump. Otherwise, you will have to blow out the system with compressed air or (if blowing does not give results) disassemble and check each part until the cause is found. When checking, we recommend paying special attention to lever 6 and its spring. And also: make sure that the roller of lever 7 does not jump off lever 6 during operation.
If the carburetor has been forgotten and has not been looked at for a long time, then it is possible that the ball valve 11 has lost its mobility (got covered in tar). Removing the ball from the socket is a delicate job, but it can be removed with a pointed punch. After the ball has been removed, it and the seat are washed with a solvent (acetone or gasoline) and put the ball back in place.
For all VAZ models, a normally operating accelerator pump should inject from 5.25 to 8.75 cm³ or from 3.5 to 4.5 cm³ of gasoline for a car in 10 full working strokes VAZ-2105. For those who wish to find out the performance of the accelerator pump, we remind you that before starting the test, you must first make 10 test runs (lever turns) to fill the pump channels with fuel.
If the normal engine temperature regime is disturbed (in this case the engine overheats), you won't achieve maximum power. On VAZ cars, with a working cooling system, the thermometer needle is set to the center of the device after the engine warms up (regardless of the ambient temperature and the nature of the movement). On models with electric fans, the pointer deviates to the red zone, and this is provided for by the design. Engine overheating is a serious malfunction that leads to engine failure. If such a defect occurs, you should check:
- the coolant level in the expansion tank and, if necessary (if the level is below the "min" mark on the side of the expansion tank), top up;
- fan drive belt tension (if it is loose, the belt may slip and intermittently rotate the water pump pulley) and tighten if necessary;
- operation of the thermostat and intervene if necessary.
It is possible that the engine overheats because of the radiator. In the absence of a special liquid Tosol, some car enthusiasts pour water into the radiator. The resulting scale can clog the radiator tubes and practically disable part of the radiator area. This defect is combated with a special product for removing scale. The removal technology is indicated on the packaging of the product. The Pervouralsk Chrome Peak Plant produces the product "Ikar". It not only prevents the formation of scale, but also protects the cooling system parts from corrosion.
It may happen that you will not find any of the above reasons, but the engine does not develop full power and does not develop it. Considering that miracles do not happen, there is still a reason, and most likely, it is hidden inside the engine. Burnt or deformed valves, burnt pistons, broken or burnt piston rings, excessive wear of cylinders - this is a list of defects that can cause loss of power, and which of them specifically - will show an inspection at a service station.
With the advent of new car models VAZ-2105 and VAZ-2107 new reasons also emerged. For example, when accelerating or moving uphill, the engine suddenly starts to run unevenly, with a loss of power. Most often, this occurs due to the vacuum ignition advance regulator. It must turn the movable plate together with the contacts depending on the change in engine load, changing the ignition advance accordingly.
The movable plate is mounted on a ball bearing and if it rotates unevenly with jamming, the breaker contacts do not work in coordination with the camshaft cams, and therefore do not provide the optimal ignition timing.
(The text is published on the portal: «VAZBOOK»)
You can check that this is the reason by disconnecting the vacuum regulator, disconnecting the hose and plugging it. If the engine has improved its performance, you can continue driving until you have the opportunity to replace or repair the regulator.
But it happens that the movable plate swings relative to the horizontal plane again because of the bearing. The previous method, i.e. disconnecting the hose, will not achieve anything in this case. The distributor must be repaired or replaced, but if you have an old model distributor in stock (from the VAZ-2101 car) you can use it temporarily too.