How to check the pressure in the fuel system of a VAZ 2107?

Necessary equipment and tools

Of course, reworking an engine requires special equipment that can make basic manipulations easier. You will undoubtedly need:

well equipped, warm garage. Agree, it is difficult to work in the cold or in the rain. Electricity is also required;
convenient overpass or garage pit. It is not recommended to use a jack or improvised devices in order to avoid unsafe situations leading to accidents;
spare car. It can be useful for quickly responding to various force majeure circumstances, such as the need to urgently replace a defective part.

To make the process easier, we recommend that you stock up on the following tools:

a set of different screwdrivers. Keys and sockets, including a wrench and a hexagon, will also come in handy;
a suitable container and a special hose up to 4 m long. Used when draining antifreeze with machine oil;
a set of adjusting washers, probes and other devices for debugging valves;
file;
a chisel, drill and grinder, which can be useful in difficult situations;
a set of various clamps.

In addition, it is recommended to keep an effective solvent on hand. This product is used to combat souring of nuts.

General diagram of the electrical equipment of the VAZ 21074 injector

1. Electrical connection diagram of the wiring harness of the instrument panel assembly LADA 21074

– ignition switch unloading relay;
– relay-interrupter of direction indicators;
– windshield wiper relay;
– brake signal switch;
– switch for headlights and direction indicators;
– windshield wiper and washer switch;
– ignition switch;
– hazard warning switch;
– instrument cluster;
– rear window heating switch;
– rear fog light switch;
– external lighting switch;
– heater motor switch;
– additional resistor for the heater electric motor;
– heater electric motor;
– indicator lamp for heated rear window;
– brake fluid level warning lamp;
– instrument lighting switch;
– cigarette lighter;
- watch;
– reverse light switch;
– hand brake sensor;
– rear fog light relay;
– block of the instrument panel harness to the ignition system harness;
– glove box lighting;
– mounting block.

No pressure in the fuel rail, reasons

The presence of a certain pressure in the fuel rail of an injection engine is one of the conditions for its operation.
Using the example of the fuel rail of the fuel injection system 2111 of the VAZ 21093 (21083, 21099) car, we will consider the signs and reasons for the disappearance or decrease in gasoline pressure in it.

Signs that there is no pressure in the fuel rail

— The car engine does not start

The starter turns, but there are no or infrequent sparks in the cylinders.

— The car engine starts and immediately stalls

After starting, the engine makes a few revolutions and stalls.

— Unstable engine speed at idle

The engine jerks, shakes, and tries to stall when idling.

— Dips, jerking and jerking after pressing the gas pedal

When pressing the gas pedal, instead of the expected increase in speed and pickup while the car is moving, the driver feels that the engine is trying to stop and stall - failure or several such attempts extended over time - jerking and jerking.

— Reduced power and throttle response of the car engine

The car's former agility and engine traction have disappeared somewhere; the car can barely pull.

Causes of the “no pressure in the fuel rail” fault

— Fuel pump is faulty

The electric fuel pump cannot create the required pressure in the fuel system due to its malfunction or a malfunction of the electrical switching circuit. If the pump fails completely, then there can be no question of any pressure in the fuel rail.

— Fuel filter clogged

When the fuel filter of the fuel injection system becomes clogged, its throughput decreases (in some cases it disappears altogether). As a result, gasoline cannot be pumped into the fuel rail by the gasoline pump with sufficient pressure, or maintaining the required pressure at different engine operating modes becomes impossible. See “Signs of a clogged fuel filter in the fuel injection system.”

— The pressure regulator on the fuel rail is faulty

Due to the loss of mobility (freezing) of the diaphragm inside the pressure regulator, gasoline from the fuel rail is constantly discharged into the return line (and not only when it is needed). Therefore, it cannot provide the required level of fuel pressure. The pressure on the injectors drops, and the less pressure on the injectors, the less efficient they work.

— The fuel lines of the engine power supply system are clogged

Low-quality gasoline containing various additives that create deposits, a fuel filter that has ceased to cope with its functions, and dirt in gasoline and in the fuel tank allow a car with high mileage to first narrow the clearance of the fuel lines and then close it completely. Accordingly, the fuel supply weakens or stops altogether. There is no pressure in the fuel rail or it is below normal.

— There is a fuel leak in the engine power system

It turns out that despite all the efforts of the fuel pump to catch up with the required level of pressure, it is constantly being released, reducing the norm. The signs of malfunction listed above appear in the operation of the car's injection engine.

— The fuel vapor removal system from the gas tank (SUPB) is clogged

This interferes with the ventilation of the fuel tank. The vapor pressure in it increases. Excessive pressure prevents gasoline from flowing normally into the fuel line. Refer to "2111 (Euro 2) Engine Evaporative Emission System Diagram".

What to do if there are signs of a “no pressure in the fuel rail” malfunction?

First of all, you need to check the pressure in the fuel rail using a pressure gauge. It should correspond to 2.5 - 3.5 bar (250-350 kPa) after the engine has been stopped.

Fitting for checking the pressure in the fuel rail of the injection engine 2111 of the VAZ 21093 (21083, 21099)

Mechanical problems

First, you should check the throttle cable. Quite often it jams, and the pedal “sticks” when the driver has already removed his foot and the speed has not decreased. This may be due to the following problems:

Corrosion of the cable
. At the same time, it simply gets stuck in the shirt;
Lubrication
. Sometimes drivers, in an effort to improve the operation of the unit, lubricate the cable; in winter, the lubricant freezes, which causes jamming;
Unsuccessful repair
. In some cases, after repairs, car owners incorrectly position the cable, resulting in problems.

Therefore, be sure to check the condition of the cable. See how it moves and replace it if necessary.

Checking the pressure in the fuel rail on all VAZ cars

Welcome! Pressure in the fuel system - in any car there is pressure in many systems, for example, in the engine lubrication system there is oil pressure, in the engine power system there is fuel pressure, etc., so most of the fluids that are in the engine are supplied under pressure, because that if, for example, there is no pressure in the lubrication system, then the engine oil will lubricate the engine very poorly and thus it will quickly wear out, and if the pressure in the engine power supply system suddenly disappears, the car will begin to twitch, stall and will not drive well, therefore The pressure in the engine must be monitored and always kept normal.

Note! In order to check the pressure in the fuel rail, you will need to stock up on only one pressure gauge, which is specifically designed for checking fuel pressure, but a pressure gauge used to check tire pressure may also be suitable; when purchasing a pressure gauge, it will have to come with a hose, but not in all cases , sometimes pressure gauges are sold separately without a hose, in this case you can use any of your own hoses or buy one specifically for the pressure gauge in a car store! (So that you know approximately what a pressure gauge for checking fuel pressure with a hose looks like, just below there is a photo in which it is depicted)

Which part should be used to check the pressure in the engine? In fact, the pressure can only be checked at the fuel rail, but also with the help of additional tools, the fuel pressure can be checked in other places, but as practice shows, this is not entirely necessary, since you can only understand what the problem is using one fuel rail, you will learn how to do this today in this article.

Note! So that you further understand what we are talking about, we will explain to you one thing that some people already know and some still do not understand what we are talking about, so two systems were mentioned earlier, namely the lubrication system and the engine power supply system, so about the lubrication system we won’t discuss it with you today since it doesn’t relate to our topic, but let’s talk a little about the engine power system. Due to the power system, the engine absorbs air and gasoline, because the car only works on a mixture of these two things, that is, if If the car doesn’t take in air, the car most likely won’t even start, and if the car doesn’t take in gasoline, then it won’t start either, so in order for the engine to work normally and stably, it needs to be constantly fed, and it is fed gasoline and air, as was said earlier, and if one of the parts that, for example, supplies gasoline fails, then the car will no longer drive, this is why checking the fuel pressure in the system was invented, because if the fuel pressure is at zero, then Accordingly, gasoline will not flow into the car’s engine and thus the car will not go anywhere! (If you are interested in what parts relate to the engine power system, then look at the article entitled: “Reducing pressure in the power system on a VAZ”, this article contains a photograph that shows all the parts that relate to this system)