How to check the fuel pump on a Chevrolet Niva

Hi all! I am dealing with a typical and common problem: the Niva Chevrolet fuel pump does not work. Yesterday I got into the car, started it - it started, but immediately froze. The first thought that came to my mind was that the fuel pump was broken. When the engine starts, a pump hum is heard, after which the relay is activated and stops the fuel supply. I left the car, the next day I started trying to start it: the pump did not hum and would not start. What to do?

You correctly noted that when you turn the ignition key, the relay is activated and the fuel pump starts working, supplying fuel to the cylinders through the lines. If you do not hear a hum from the pump, there is most likely a problem. To find out if this is actually the case, you need to follow a few simple steps. Let's talk about everything in order.

Chevrolet Niva fuel pump does not work: what to check?

Once upon a time I was also wondering what to do and where to look first if the fuel pump does not work. To begin with, I recommend removing the negative terminal of the battery in order to “reboot” the brain of the on-board computer. If after this the pump starts working, great, the problem is solved. But this doesn't happen every time.

So, the order of further actions is as follows:

We open the hood, find the fuel rail, there is a side hood, under which there is a coil. Find the valve there, click on it. Did you run out of fuel? If yes, then great!
A thin stream of fuel? Try turning the ignition key several times, then press the valve again
If nothing works, most likely there is no pressure in the system, which means the fuel pump has failed

Don't forget to check the fuse. It may burn out, so the pump simply cannot work. We move the front passenger seat and find the fuse under the cabinet. We check, if it’s working, we move on. If it burns, replace it with a new copy.

Video instructions for replacement:

A fairly common option: “It’s getting cold outside. I got into the car, started it, and the car immediately stalled!” My first thought was “the fuel pump is broken.” The starter spins briskly, but doesn't grab a beat.

0) When the car is working properly, when you turn the ignition key, you hear a click from the fuel pump relay (under the glove compartment, at the passenger’s feet), after which the fuel pump hums for 4-6 seconds (increases pressure), after which the relay clicks again. Also, the relay and pump operation can be heard while the starter is running. (But due to the operation of the starter itself, it is very quiet).

In my case, the relay was audible, but the pump was silent.

But you should keep in mind that clicks and the pump will only be heard the first 2 turns of the key. After this, Boshev’s “brains” block the work of pressure, it is believed that there is pressure in the system.

You can reset the negative terminal from the battery for a few minutes (reset the “brains”). After this, the pump will turn on again.

Make sure there is gasoline in the gas tank. (although the relay will click without it, the pump will be audible even without it).

What to check, where to crawl. 1) We get under the hood. Fuel rail (where the molds are) At the end of the ramp (from the windshield side) there is a cap. Under the cap there is a spool (valve) that, when pressed, gasoline should flow from the ramp in a good stream. After several attempts to start the key, there should be a trickle. You can check with two people (one turns the ignition key, the second checks the pressure in the rail). If there is pressure, everything is fine with the fuel pump. That's not the reason.

Checking the fuel pump relay Niva Chevrolet

Sometimes the fuse dangles in its socket, although it is intact and in good working order, but in this case it will not work. Check if it is tight, if necessary, press the “legs” of the fuse, just be careful, it will be more reliable and effective. So, let's move on to the relay race. If you hear the relay click when you start the engine, it is more likely to be working correctly. Otherwise, the mechanism must be checked and changed.

suitable relay for 12 V and 30 A - article number 752.3777-121. But before changing the coil, check the wiring. Perhaps where the break occurred or where the contact oxidized? There is a small hatch under the rear seat on the right side, open it, remove the connector, check the voltage with multimeters - it should be 12 V. If the readings differ significantly, look for the place where the circuit break occurred. This way we find the problem area evenly and evenly and thereby eliminate the problem. Good luck.

How to diagnose a fuel pump?

Do not rely solely on the auditory effect. If you cannot hear the fuel pump in your car, you should not immediately go to the store to buy a new device. Also, do not dismiss problems with the pump if you hear it working when you turn on the ignition. Just because the fuel pump is “buzzing” does not mean it is working correctly. It is quite possible that the internal part is worn out, or leaky elements have appeared that relieve pressure from the fuel system and prevent the fuel pump from collecting the required fuel pressure in the fuel line and in the injector rail.

Diagnostics should include several stages:

checking the fuel pump fuse is an important point that should be performed if the buzzing of the device is not heard when you turn on the ignition, since power may simply not be supplied;
checking the wiring is also one of the important points, because many power failures are associated with broken or oxidized wires, this needs to be checked before going to the workshop;
checking for errors in the on-board control system - ECU diagnostics can tell you which sensor has failed, because often fuel equipment does not work well precisely because of incorrect sensor readings;
measuring the pressure in the injector rail - on many cars, using a special pressure gauge, you can measure the pressure in the rail in order to understand what indicators the fuel equipment shows;
checking the fuel pump directly - this can be done at a service station to obtain reliable information about the condition of this unit, but there are also opportunities for self-diagnosis.

Tips for motorists

The operation of any internal combustion engine is impossible without supplying fuel to the combustion chamber. This process is equally important for both carburetor and injection engines. The fuel mixture is supplied by a fuel pump, which is electrically driven for multipoint injection systems. Therefore, failure of its operation on this car is almost always associated with the electrical circuit of the car.

What to do in this case

This is a very unpleasant time, especially when it happens on a busy city highway or during rush hour. If there is nowhere to wait for help, you should move the car off the road and try to “revive” the gas pump yourself. To do this, it is recommended to have a car tester or at least a test lamp. The first sign of such a malfunction is that the engine does not start, and when the ignition is turned on, the sound of the fuel pump electric motor is not heard.

Auto electricians recommend disconnecting the battery terminal for a few minutes and trying to restart the engine. If the problem persists, continue troubleshooting. Now you need to get to the pump to check the presence of supply voltage at its terminals. One terminal of the warning lamp or tester should be connected to vehicle ground, and the other to the gray wire of the electrical connector on the fuel pump. There are two possible control options: the presence of voltage or its absence. The first case indirectly confirms the breakdown of the electric motor, the second suggests continuing the search.

Where is the fault located?

Failure of an electric motor is a fairly rare occurrence, so we will focus on the case when there is no supply voltage at the pump terminals. When checking for power supply, note that the control unit initially emits a pulse to start the pump that lasts only 5 seconds. If the engine does not start, there will be no more impulse. Therefore, before checking the supply voltage, it is necessary to relieve the fuel pressure in the rail.

Power is supplied through the relay contacts. This is not very easy to check, since you need to remove the plastic cover under the glove box on the front panel. There is a relay block and a deep fuel pump fuse. To check the relay, it must be replaced with another one. Most often, burnt-out contacts of this relay are to blame. In some cases, problems are created by an additional relay that is part of the alarm system. When the vehicle is armed, it blocks the fuel pump power circuit, preventing the engine from starting.

The fuel pump is an important element of the fuel system, performing two functions:

Supplies gasoline to the injectors.
Creates high fuel pressure in the fuel line.

The Chevrolet Niva is equipped with an electric pump, which is controlled by the vehicle's electronic system.

The fuel pump does not pump when the ignition is turned on

First of all, you need to check the fuel pump terminals and the power to them. In the photo, the terminals were worn out, which caused the contact to close and the fuel pump to melt.

What to do if such a situation arises. The verification algorithm is described below. Briefly check the presence of voltage at the fuel pump terminals. Based on this, further conclusions are drawn.

Checking the fuel pump circuit

Checking the power circuit.

If you know that the pump is working (to do this you need to gain access to it, remove it and connect it to an alternative power source), then the reason should be looked for in the car's wiring. To do this, the control light should be connected to the gray wire that goes to the pump.

This is exactly what is a plus. If the light does not light up, then power is not supplied to the unit.

Checking relays and fuses

Here you should initially check the fuses and relays. The fuse box is located behind the left of the driver under the dashboard, and therefore is not easy to access. You will have to unscrew two bolts and remove the decorative protective cover.

If these components are faulty, they should be replaced. The relay is checked in the same way as the pump, by connecting a test light to the input and output . The fuse can be checked visually.

The fuel pump relay is marked with a green arrow.

If the car still does not start, you should check the connector block. It is located behind the driver's side fuse box in the passenger compartment. Here you can also use a test light or tester, with which you can check the voltage at the inputs/outputs.

Design and principle of operation

The Chevy Niva fuel system uses a submersible fuel pump, which is based on a brushed motor with two permanent magnets on the stator.

The pump is driven by a relay, the control contact of which is connected to the engine control unit. The circuit is protected by a fuse that prevents the wiring from turning on in the event of a short circuit.

The relay is located in the passenger compartment under the glove box. The fuse box is nearby.

Often the fuel pump is not called the electric motor itself, but a module that includes:

Plastic housing with load-bearing function.
Coarse filter that traps large contaminants.
The pressure regulator is a bypass valve that returns excess fuel to the tank.
A sensor and float that read information about the fuel level in the tank and transmit the data to the on-board computer.

The electric pump is installed below the gasoline level. This ensures lubrication and cooling of its parts. If you run out of fuel completely and the electric pump runs dry, it will quickly fail.

The rotation of the pump impeller ensures pressure in the fuel line within 3.6-4 bar. If this value is exceeded, the bypass valve of the pressure regulator is activated.

Gasoline enters the impeller through a mesh filter that protects the unit from large foreign particles. Fine-grained dirt does not damage the fuel pump.

Types of fuel pumps

Let’s immediately say that this is not the only type of fuel pump. Until the mid-70s (and in the Soviet Union and Russia until the 2000s), carburetor cars with a mechanical fuel pump were widespread, which was located directly on the engine and was driven mechanically - from the camshaft cam via a pusher. By pressing the lever at a certain interval (depending on engine speed), the pusher pumped fuel into the carburetor. There was no great pressure, as you may have guessed, in such a system, nor was there any need for it. With the advent of the fuel injection system, mechanical gasoline pumps have sunk into oblivion, giving way to high-performance electric units. If the former could pump fuel under a pressure of 0.3-0.5 atmospheres, then the latter, on average, produce all three.

Main malfunctions and their possible causes

Problems in the operation of the fuel pump manifest themselves in the operation of the engine, which begins to behave incorrectly:

Doesn't start or crashes.
It idles, but does not develop high speeds.
It doesn't develop enough power.
Unstable minimum.

Similar symptoms appear when there is a malfunction in the ignition, injection and other key systems. However, it’s worth starting by checking the pump’s operation.

Problems arise for the following reasons:

Broken wires or oxidation of contacts in the power supply circuit of the relay and fuel pump.
The pressure regulator is faulty.
Relay or fuse failure.
The fuel filter is clogged.

Important: if the coarse filter is dirty, not enough gasoline is supplied to the electric motor and it overheats. If the problem is not corrected in time, the fuel pump will fail.

The main signs of a malfunction - how to understand that fuel is not supplied?

First you need to figure out whether the fuel pump is to blame for the problem. Very often, car owners come to a service station and declare the need to replace fuel equipment, but in fact, only a fuse or a certain filter needs to be changed. You should take a closer look at how the car behaves, what errors are shown on the on-board computer screen, and how the engine reacts to an attempt to start. All these features will tell you whether the fuel pump is to blame for the problem, or whether you need to look for other problems.

The main signs of fuel pump failure:

when you turn on the ignition, you can’t hear the operation of the fuel pump, which should turn on at this moment and pump up pressure (in some cars the fuel pump turns on when the driver’s door is opened or when the security system is disarmed);
when trying to start, the engine does not start at all, the starter turns the power unit monotonously, there is no hint of an attempt to start - this happens when the pump is completely faulty;
at the moment of starting, the engine starts, but then it starts to work very unstably, the speed fluctuates, errors appear on the BC screen, the engine stalls, knocks, “chokes” - this happens when the functions of the pump are disrupted;
Also, at the initial stage of failure of the fuel pump, problems are possible while driving, when the engine starts to run unevenly, stalls or reduces speed while accelerating, and dips appear;
if the pump suddenly fails, the engine gradually reduces speed and stalls, despite the driver’s attempts to press the gas pedal, and then the engine simply does not start.

There may be other symptoms, it all depends on the nature of the breakdown. You should pay attention to the overall operation of the engine. Sometimes the fuel pump begins to fail due to minor problems. At some moments, the fuel pressure is not enough for stable operation of the unit, and it may stall. After restarting everything starts working normally again. But very often the failure is spontaneous and occurs unexpectedly while driving or after the car has been parked for a long time. If the spark plugs are dry, there is fuel in the tank, the starter turns the engine without problems, the battery is charged, you need to carefully examine the fuel pump.

Trouble-shooting

The engine will not start if the fuel pump does not supply gasoline to the fuel line.

In this case, the check begins with the fuse. If it works properly, you need to make sure there is voltage at the fuel pump terminals. For diagnostics you will need a multimeter. Raise the rear seat and remove the pump cover. If, when the ignition is turned on, 12 volts are supplied to the terminal and the pump motor fails, the unit must be replaced.

Often the pump stops working due to terminal oxidation. Therefore, inspect the connector and, if necessary, clean it of corrosion.

If there is no power, it is necessary to check the operation of the relay and the integrity of the wires.

Interruptions in operation or insufficient engine power are a consequence of loss of pump performance and a drop in pressure in the line. This happens for three reasons:

Voltage drop across oxidized contacts.
The coarse filter mesh is dirty.
The pressure regulator is faulty.

First check the status of your contacts. Then disassemble the fuel pump and remove the filter. At the first sign of contamination, the mesh should be replaced with a new one.

To check the operation of the pressure regulator, a pressure gauge is required. Connects to the fuel line outlet. The operating pressure with the ignition on must be at least 3.6 bar.

Types of fuel pumps

The photo shows a VAZ 2106 fuel pump. Older engines were equipped with mechanical pumps. They were driven by a lever from the motor. Electric pumps are installed on new cars. They are either located next to the fuel tank or inside it. They work on all vehicles with fuel injection engines as they require higher pressure in the fuel supply system. In mechanical pumps there cannot be an intermediate state: they are either fully operational or immediately fail, and then with a full tank the engine does not start or simply stalls. Electric pumps may feel “bad” for a period of time, and then the problem can be noticed by a decrease in power and noise.

Checking fuses and relays

Fuel pump relay
As a rule, the operation of the pump is easier to control on domestic cars. This is because its operation is clearly visible from inside the car. A characteristic buzzing sound is a sign that the pump is working.

If there are no sounds, then you should immediately check the fuses and relays. On VAZ models they are located under the glove compartment or in the heater console on the passenger side. You need to unscrew the fixing screws and remove the side panel.

But on GAZ cars and some foreign cars, the electrical contactors are located in the engine compartment, in a special mounting block.

The relay fails mostly due to the short circuit of the switching circuit. It is recommended to check it first. If the car does not have a pump relay (such systems also exist), you need to test the power at pins 85-86. The values can be diagnosed using a control indicator with low-ampere current consumption. Otherwise, the indicator will deteriorate.

Circuit breakers

The result is displayed according to the following indications:

if the indicator on one of the terminals does not light up, you can judge that there is no power to the relay;
if the indicator shines brightly on one terminal and dimly on the other, this indicates an imminent failure of the relay and its unstable operation.

In the first case, the fuse may blow or the wire supplying the main power may break. In the second, there is likely a bad contact in the connections between the block and the relay. To check the last option, you need to remove the relay and then connect the terminals with an indicator. The device light will light up, which will indicate a weak contact. As a last resort, if the indicator does not light up, you need to check the serviceability of the controller itself or the connecting wiring.