Low fuel light on: how far can you drive? Driving with a burning fuel light - is there any harm? Does the light stay on when you run out of gas?

29.06.2020

A clear belief has taken root in the automotive environment - driving with a small amount of fuel in the tank, when the minimum fuel lamp has already lit up, is harmful to the car. This is evidenced by the driver's rumor, this is indicated by the instructions for the operation of cars. At the same time, there is no direct dependence, they say, once I drove with a burning lamp and everything broke down, and this seriously complicates the conversation on this topic - it is not known for certain what affects what and what leads to. There are only observations and theoretical experience. But we still tried to analyze the situation and understand how harmful it is to drive on a burning fuel light. For this, let's consider the most popular arguments and confirmations used by supporters of this point of view.

Fuel pump overheating

In modern injection cars, submersible pumps are used, they sink into the tank and “live” among gasoline. it does not just lie there, but is located in a special fuel module, which, among other things, includes a plastic drip cup, fuel level and much more. The fuel pump itself is located inside this entire structure; during operation, it generates heat, which means it must be cooled. The fuel pump does not have additional systems that remove heat (in general, this is a rather simple design), so cooling is done by gasoline - both by what passes through the pump itself and by what floats around in the tank. If there is little fuel in the tank, then heat dissipation deteriorates, the pump overheats, can be deformed and jammed. Due to the increased temperature, the windings can collapse, the electrical connectors can melt, in general, there is little pleasant.

This is the most popular point of view regarding the dangers of driving on a light bulb, and it is quite logical. True, for some reason it is not taken into account that even when there is little fuel in the tank, the gasoline pump does not work “dry”, it still pumps gasoline through itself. As soon as the gas runs out, the engine stalls, the pump stops working - it turns out a kind of protection from a fool. Is there enough cooling for passing gasoline? Purely theoretically - yes, because the gas pump is not a very powerful unit and does not emit much heat during operation. We managed to find a couple of experiments on the Internet that confirm this point of view. But they, of course, were carried out under sterile conditions, no one measured the temperature in the tank.

Dirt and water at the bottom of the gas tank

At whatever gas stations we refuel, with an increase in mileage, particles of various impurities and water accumulate at the bottom of the gas tank, which forms in the gas tank in the form of condensate. This is an indisputable fact (in a good way, the tank needs to be cleaned periodically), but there is an opinion that when there is not enough gasoline in the tank, the concentration of "harmful substances" increases and the likelihood of filter clogging increases. A clogged filter does not pass fuel well, the pump is unstable and breaks, and water can go further along the fuel system and lead to breakdowns, or even.

Dirt in the gas tank. Photo - drive

On the one hand, it sounds logical, but on the other hand, the fuel intake design is designed in such a way that it always takes gasoline at the very bottom of the tank, and since “harmful substances” are heavier than fuel, they will still accumulate from below, no matter how much gasoline is in the tank was. Clogged fuel module filters are certainly a problem, but it's not very clear how it is related exactly to an empty tank and driving on a light bulb. In addition, deposits appear with time and mileage, but no one says that a burning lamp is harmful only for used cars; new ones are also not recommended to drive to the last.

Air ingress

Another theory says that with a low fuel level the fuel pump intermittently "grabs" air, and this harms his work, he is poorly lubricated and rubs “dry” and breaks.

It is also logical and also not all clear. The presence of an anti-drain glass allows you to smooth out fluctuations in the fuel in the tank during turns, accelerations and braking, the gas pump can start to grab air only when the fuel is almost over, but the pump will not work for a long time in this mode, if there is no fuel, the engine will stall, and a large there shouldn't be any harm.

Here are the main three reasons that are given as a justification for the harm of driving with low fuel levels. Each of them has a healthy grain, but none of them allows you to fully theoretically substantiate the problems that can arise from an empty tank. Meanwhile, the opinion of drivers and recommendations of manufacturers still do not arise out of the blue- a very large empirical experience has already been accumulated in order to notice the connection between a low fuel level and the failure of a gasoline pump.

Not one-time cases, but statistics say that those who constantly drive with an empty tank are more prone to pump failure. This is especially noticeable on cars with, their owners usually do not refuel a lot, they only need gasoline to start - according to statistics, the gas pump on such cars lives less. It is hardly worth ignoring such statistics.

At the same time, of course, everything is individual - cars are operated in different conditions, gasoline pumps have a different design, fuel quality is also different, so it is impossible to say for sure that for all cars the consequences of driving are equally negative and lead to the same consequences - someone will break already after the first "bulb", and someone drives all his life without problems, pouring 5-10 liters into the tank, simply because the fuel pump is very hardy or so the cards lay down.

One thing is certain - a low level of fuel in the tank will definitely not prolong the life of a car, and if you still refuel, then why not just do it more often. You will not lose anything (after all, you still pay for fuel), but in which case you will extend the life of the fuel pump. Isn't such reasoning enough to get rid of the habit of driving "on a light bulb"?

To inform the driver about the amount of fuel in the car tank, a fuel level indicator is installed on the dashboard. By itself, it is not particularly noticeable, and in order to exclude the possibility of a complete consumption of gasoline or diesel fuel, there is an additional signal lamp on the dashboard, indicated by a schematic representation of a gas station.

When the light comes on, the light informs that there is critically little gasoline in the tank and it will be enough to cover a short distance. The fuel level warning light is made so that the driver notices in advance that there is not enough fuel in the tank and drove to the gas station.

The signal light can be considered a useful addition to the fuel gauge. The fact is that the sensor readings are not always accurate, there are certain errors (due to the configuration of the tank, the position of the car and a number of other factors). Therefore, the sensor can show an “empty” tank when it is ¼ or 1/5 full, depending on the volume of the tank (which is 10-15 liters). This can be confusing for the driver, because the gauge needle shows "0" both at 10 liters and at 1 liter of gasoline in the tank.

Types of indicator, principles of operation

On cars with carburetor systems, the signal lamp was powered from a potentiometric one, that is, the sensor and the lamp are connected. The principle of operation is very simple - when a certain level of gasoline is reached, the potentiometer slider connected to the float closes the lamp power contacts. At first, the contacts close intermittently (the splashing of gasoline in the tank affects), so the indicator flashes, but with greater fuel consumption, the lamp contacts become permanently closed.

In modern cars with an injection power system, the sensor and indicator are separated. The signal lamp is powered by its own sensor mounted on the pump housing. The main element of the signal lamp sensor is a thermistor placed in a metal bulb. The principle of operation of the "lamp-sensor" circuit is based on a change in the resistance of the thermistor due to temperature.

Everything works like this: voltage is applied to the thermistor, which causes it to heat up. The fuel acts as a coolant for it, it removes heat, maintaining the temperature of the sensor. If the gasoline level drops below this sensor, the temperature of the thermistor will rise, which leads to a change in its resistance. As a result of the change in resistance, the lamp lights up.

The indicator built on the basis of a thermistor is good because it is not connected to the fuel level sensor and works independently of it. This makes it possible to notice a decrease in the fuel level even when the fuel gauge is not working.

How far can you drive with a light bulb on

Now about how much gasoline remains in the tank if the lamp lights up and how long it lasts. This indicator differs for different models. On average, automakers set a reserve per 100 km of travel. That is, the light comes on if there is between 5 and 10 liters of gasoline left in the tank, depending on the model. But this does not mean that after the signal lamp lights up, the driver will travel 100 km. The distance that can be driven on a reserve of gasoline is affected by driving style, road conditions, engine load, etc. That is, one driver will drive 80-90 km on reserve, and the second will only be enough for 30-40 km. Therefore, you should not hope that you will drive a long distance on the remaining fuel in the tank. When the indicator lights up, you should immediately head towards the gas station.

How to drive if the petrol light is on

It happens that the gasoline light on the dashboard lights up, and you still need to drive a considerable distance to the gas station. And in this case, measures should be taken to ensure that the reserve is enough before refueling. For this you need:

Choose a path with a minimum number of stops. Keep in mind that 5 liters of gasoline is not enough to start the car and get to the gas station. You need at least 10 liters so that the pump can fully pump the power system and ensure a stable supply of fuel. If there is less gasoline, then the fuel pump will “drive” air due to a lack of gasoline, because of which the engine will not be able to work stably.
Choose a speed mode at which gasoline consumption is minimal (70-80 km / h).
Reduce the load on the on-board network, leaving only the necessary electrical equipment on.
Close the windows, park behind the truck on the track, this will reduce air resistance to a minimum.

These measures will allow you to drive a greater distance on the remaining fuel.

What threatens a small amount of gasoline

Note that it is better not to allow the amount of fuel to decrease to the level when the warning light comes on. If for carbureted cars a small amount of fuel does not have any negative consequences, except for the likelihood of an unexpected cessation of movement and a “walk” with a canister to a gas station, then this phenomenon is dangerous in injection cars.

The problem is that the fuel pump in such machines is placed in the tank and the fuel for it is the coolant. If there is not enough gasoline, then due to overheating, the pump motor may fail. The "snatching" of air by the pump also does not bring anything good.

Another problem is that at a low level, the fuel pump pumps fuel "from the bottom" of the tank, where rubbish and dirt accumulate. This leads to clogging of the fuel inlet filter, causing the pump to work under increased load, which increases the likelihood of failure.

Video: The light bulb came on, how long will the fuel last?

It would seem, what is there to talk about? Information about the reserve in the fuel tank must be contained in the vehicle's owner's manual. Or even simpler: the trip computer warns of low fuel levels and tells you how far you can drive before refueling. Not always. Others, instead of specific numbers, issue only dashes, forcing them to panic even more.

However, the authors of instructions often limit themselves to general words. For example, "The low fuel warning light comes on when the fuel tank is nearly empty." This is a quote from the instruction manuals. It even contains an element of drama: "The depletion of the fuel supply can endanger the people in the car." Scary...

What threatens the "light bulb"

Similar exercises are found in the instructions of three bestsellers - Renault Logan, Renault Duster, Lada Largus. As a carbon copy: "If the lamp lights up and does not go out, it is urgent to fill the tank with fuel." At the same time, the manual of the related Renault Sandero clearly states - "from the moment the warning light first lights up, you can drive another 50 km."

In the instructions for Lada Vesta there is a mention of a control lamp, and more should be said in the appropriate section, but the link leads nowhere. There is not even such a section as "Vehicle Operation". There are "Introduction", "Driving", "Care" and "Practical Advice". On the contrary, Lada 4x4 has specific data (see the table). Same with Chevrolet Niva. It looks like a legacy of the Soviet era. But the Japanese and Europeans (Germans and Czechs) are just as accurate.

Stop panic!

As you can see, in order to find the answer to the question of how much and how far you can drive "on a light bulb", I studied the operating instructions for the most popular cars in Russia. The data was summarized in a table. Conclusion: the minimum supply of fuel that automakers provide us is 5 liters, in most cases - about 7 liters. This should be enough for at least 90 kilometers when driving on a country road in a B-class car. So it's not worth panicking when you see a low fuel lamp on or a written warning that the tank is almost empty - unless, of course, you are in the tundra or desert. Get to the gas station.

To find out where the nearest one is, look at the navigator map by turning on POI and filtering by gas station. No navigator - stop to use your smartphone or tablet. A short break won't hurt. Of course, it is better to find a network gas station with high-quality gasoline, but if there is no guarantee that one is nearby, it is better not to risk it and refuel at the very first - minimally. When you get to a decent one, fill up a full tank and dilute fuel of dubious quality. And wait a couple of seconds after turning on the ignition before starting the engine: let the pump pick up normal gasoline.

Should I be worried if the low fuel indicator light on the instrument panel lights up, how much more can I drive and how to save gas? We answer in order.

An indication of the need to refuel is usually accompanied by a single beep. Hear this "ding" - start counting.

However, the authors of instructions often limit themselves to general words. For example, "The low fuel warning light comes on when the fuel tank is nearly empty." This is a quote from the Hyundai Solaris and Kia Rio owner's manuals. It even contains an element of drama: "The depletion of the fuel supply can endanger the people in the car." Scary…

Low fuel light on

If you have to travel out of town, just in case, keep a small canister of fuel in the trunk. Check that it closes tightly. It is more convenient when it is completed with a watering can for refueling. As in this illustration, for example.

Meanwhile, “drying out” is bad: you can find a lot of unpleasant adventures both for yourself and for the car. For example, burn the fuel pump, which will not have enough cooling. In addition, it will begin to pick up the dirt that is in the tank of any car with high mileage. A lean mixture can damage the catalytic converter. When the engine is running at high speeds, and the fuel mixture stops flowing into it (for example, in a long bend), this can lead to detonation and subsequent repairs. If it takes place in a mountainous area, there is a risk of not overcoming the climb. And in general, any forced stop far from civilization is unsafe. In winter, you can simply freeze, being afraid to leave the car. Think fiction? Alas, it happens. And not only in Siberia and the Far East, but even in the central zone of Russia.

To reduce fuel consumption, turn off the air conditioner. This is a very greedy unit.

In fact, both Solaris and Rio have not so little in reserve: 7-8 liters, as the owners of such cars say. So, maybe it is worth giving such figures, having previously checked? For the concern, this is quite a feasible task. Or has this horror been removed from the instruction manual for the new Hyundai Solaris, which is about to appear on the Russian market? It will be interesting to check when we get to know him.

In the instructions for Lada Vesta there is a mention of a control lamp, and more should be said in the appropriate section, but the link leads nowhere. There is not even such a section as "Vehicle Operation". There are "Introduction", "Driving", "Care" and "Practical Advice". On the contrary, Lada 4 × 4 has specific data (see the table). Same with Chevrolet Niva. It looks like a legacy of the Soviet era. But the Japanese and Europeans (Germans and Czechs) are just as accurate.

Leave the Power mode until better times. Switch to Eco Mode, avoid sudden acceleration and deceleration.

How much gas is in the tank when the light comes on

A common feature of champions in efficiency (among them is the Volkswagen XL1, which consumes only a liter of fuel per 100 kilometers) is impeccable streamlining.

We crawl, hobble in the darkness...

How to get to the gas station? Close windows to improve aerodynamics and turn off air conditioning if possible (air conditioning is a serious energy consumer). Turning off the music is pointless, it won't eat much. Leave the headlights on too - otherwise you will save on safety, what you can’t do, no matter what happens. You need to move as evenly as possible, without sudden acceleration and braking, in top gear, at a speed of about 80 km / h (not in settlements). Our editor in 2008 went to St. Petersburg and back on one tank driving a 170-horsepower Volvo.

Cruise control is a good tool for saving fuel. You just need to learn how to use it correctly.

To maintain a certain speed in the middle of the last century, cruise control was invented, it is also a tempomat, which most cars have today. Cars with new automatic transmissions are, in principle, more economical than cars with mechanics - they change gears according to a certain algorithm, and not randomly, and are trained primarily to conserve fuel. But even in modern cars with a manual gearbox (for example, Lada Vesta), “gear shift prompts” (AvtoVAZ’s term) are built in. And even in the ancient Zhiguli there is an econometer that suggests the optimal driving mode. And in foreign cars of the latest generation, as a rule, you can select the appropriate mode of operation of the power unit by pressing the Eco button. Use the maximum available tools. If you can, check the tire pressure and bring it up to the prescribed pressure (the data is on the back of the gas tank flap or on a plate in the doorway). Are you traveling, do you have a box on the roof and a trailer on the tail? To get to the gas station, get rid of both, pick up when the fuel is full.

But in general, we wish you never to see the fuel reserve light on, always fill the tank under the cork, and if you sometimes go out of town, keep at least a five-liter canister with a built-in watering can in the trunk. It is inexpensive, 500 rubles, does not take up much space. If it closes tightly, hermetically - it does not even smell. We do not recommend carrying plastic bottles with gasoline: they are more dangerous than canisters. And the car burns to the ground in a couple of minutes.

And lastly, the instruction manuals are an interesting read. I advise.

Page from the instruction manual Lada 4 × 4 (ex-"Niva"). Everything is clear and very clear.

How much gas is left in the tank when the light comes on

brand, model	Fuel reserve as indicated in the owner's manual	Notes
Hyundai Solaris	No data, "the warning lamp comes on when the fuel tank is almost empty."	According to users, Solaris has at least 7 liters in reserve, which should be enough for 100 km on a country road.
Kia Rio	Similarly	Similarly
Volkswagen Polo	"Constantly on when there is fuel left in the tank for about 80 km."	And here, according to users, the reserve is 7-8 liters, not less than 100 km.
Skoda Rapid	"The warning light comes on when there is approximately less than 7 liters of fuel left in the tank"	Rapid has several options for powertrains. But even in the most powerful version of the reserve should be enough for more than 100 km.
Renault Duster	There is no data, "if the lamp lights up and does not go out, it is urgent to fill the tank with fuel."	According to the owners, a reserve of at least 7 liters (often referred to as 8 liters) should be enough for 90 km.
Renault Logan	Similarly	Reserve - about 5 liters, should be enough for 90 km.
Lada Largus	Similarly	Similarly
Renault Sandero	“From the moment the warning light comes on for the first time, you can drive another 50 km.”	In fact, the reserve in the tank is at least 5 liters, perhaps 7.
Lada Granta	No data, "lights up amber when refueling is required to avoid engine interruptions."	The owners claim that the reserve is about 8 liters. More than 100 km way!
Lada Kalina	Similarly	Similarly
Lada Vesta	No data, the corresponding item in the instruction manual could not be found.	The reserve is 7–8 liters, also for 100 km or more.
Lada XRAY	“From the moment the signal light comes on for the first time, you will be able to drive about 50 km.”	The reserve in the tank is 6–7 liters of fuel. Like the Renault Sandero.
Lada 4×4	"Illuminates orange when there is less than 4-6.5 liters left in the fuel tank."	Niva, that is, Lada 4 × 4, is not the most economical car. The minimum consumption, according to passport data, is 9.1 liters. per 100 km. In total, you have less than 90 km in stock. Alas.
Chevrolet Niva	Similarly	Similarly
Toyota Camry	"Indicates that approximately 10.5 liters of fuel or less is left."	Such a reserve should be enough for another 100 km!
Toyota RAV4	"Indicates that the remaining fuel is 9.0 liters or less."	The minimum fuel consumption on the highway version with a 2.0-liter engine is 6.3 liters per 100 km. But do not flatter yourself and take risks. Refuel as soon as possible.