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Why is it not worth driving on the reserve?

Why is it not worth driving on the reserve?

Are you one of the drivers who like to drive until the fuel gauge dash is almost at the bottom? If so, you can rest assured that you are not alone in this. According to many studies, both local and global, more than half of drivers decide to refuel their car only after the yellow fuel light on the dashboard starts flashing, and some of them continue driving even with the light constantly on.

Whether it's laziness or illogical thinking about how to save money, testing your car's engine limitations this way is sure to end in an unhappy ending. Most often it ends with a lack of fuel, usually in a place where there is no gas station in sight (which is actually a less painful consequence) or a breakdown, repair of which requires expenses worth hundreds or thousands of zlotys. The moral of the story is that riding the reserve is definitely a bad idea, so in trying to pinpoint the potential consequences, we have compiled a list for you.

Fuel is running out

As we have already mentioned, the first danger of running on reserve is the tank without a drop of fuel. A large part of drivers is based on the erroneous assumption that as soon as the fuel indicator starts flashing, there are still several dozen kilometers to drive. So where is the problem?

First of all, fuel level gauges, even in the most modern cars, are not precise measuring instruments  due to the fact that their operation is based on a relatively simple technology, i.e. a fluid level that is transmitted to the indicator electronically or through metal, strips and coils. Explains why the gas level in the fuel tank can go up or down when the car is on a slope.

Second, the fuel gauge does not always represent a fixed parameter and depends on many factors, such as the driving style which may be less or more economical, or the car model.  For example, a Mercedes C-Class can drive an average of 74 kilometers after the fuel lamp is lit, while the Vauxhall Astra is likely to give way after 42 kilometers.

If it seems to you that leaving a gas station on the road without a trace of it is the biggest challenge you will have to face when it comes to an empty tank, then you are very wrong. This is where the "fun" begins. An empty tank can cause severe damage to seals, pumps and injectors in diesel engines due to the fact that in the absence of fuel, they are forced to draw from the air, and not from a rich, oily mixture of diesel fuel and lubricant. With some types of diesel engines, depending on the pump used, with an empty tank, air will top up the tank, thus preventing new gas from entering the tank from entering the engine, which can lead to the car freezing. In this case, professional service intervention is required. In the case of gasoline engines, the situation is a little less harmful because, in the absence of fuel, they tend to "swallow" air, so it is important that the battery has enough electrostart capacity to suck in new fuel.

Overheating of electric pump motors

Overheating of electric pump motors

When the car runs out of fuel, the engine begins to overheat and the windings begin to melt. 

Fuel is transferred from the car's tank to the engine by an electric fuel pump. Once the tank is full, the gas enters the fuel pump through a part called a strainer and passes through another circular pump before finally going to the electric pump motor to cool the copper windings. When your car runs out of fuel, the windings are cooled with air, not fuel, causing the engine to overheat and the windings to melt.  That's why you often hear experts saying that a pump running on an empty stomach is not a good thing.

In addition to cooling the engine, the fuel also lubricates its rotating parts, thus preventing engine wear.

Corrosion of the fuel injection system

When the tank is mostly empty, due to the temperature difference, condensation forms, which will corrode the fuel injection system, which in turn leads to problems with the proper operation of the engine . Note the transition periods when the daytime temperature rises above 10 degrees Celsius and the night temperature drops below 0 degrees Celsius. This is especially true for cars with a tank capacity of up to 100 liters, which consequently turn into empty wheelbarrows full of condensate.

This problem becomes even more apparent on older cars whose tanks are made of tin, as opposed to the tanks of modern cars which are made of plastic. . Tin affected by the above-mentioned condition corrodes and mixes with the gas, which very often leads to pump failure, so at high speeds, which stimulate increased fuel flow through the injection system, the car may simply slide with you on the move.

Clogging filters

Filter clogging

The less fuel, the greater the residue concentration in the fuel tank.

Imagine you have a bottle of decent red wine… The leftovers at the bottom of the bottle are something you definitely don't want to drink, right? The same goes for cars.

The remainder is a solid which increases when the car is refueled. With a full tank, the residual concentration is negligible. For example, with a volume of 50 or 60 liters, a residue concentration of about 50 ml will not pose any problems. However, when we drop to 5 liters of fuel, the residue concentration increases by 10, which increases the engine's ability to pick up residues. Thus, while sludge is an inevitable part of any tank, the concentration is lower when there is more gas in the tank, preventing the filters and electric pump from clogging.

When it finishes you fuel runs out, the engine picks up residues from the bottom of the tank, which clog the filters and the electric pump. When this happens, driving becomes increasingly difficult as the engine is not getting enough gas.

What will happend if you will always drive on reserve?

In short, postponing your duties, especially when you are running out of fuel, for whatever reason, can turn into a very unpleasant experience that may end up paying a lot more (towing service, repair and part replacement) than you would have to. if you could refuel the tank in time.

If you still find yourself riding on the reserve seeing that we are all human and prone to occasional oversight as such, stick to the following instructions:

  • Drive sparingly, maintaining a speed of between 64 and 80 km / h where permitted of course, and avoid sudden braking and acceleration;
  • Try to maintain a speed that keeps the engine in the range of 2000 to 3000 rpm;
  • Turn the engine off during stops to save fuel, but only when stops are longer than a minute, as starting the car uses the equivalent of about a minute of fuel with the engine running at 2500 rpm.

We recommend that when the fuel warning light comes on, which means that you are dipping into the car reserve, take it seriously. Its role is to get our attention, which is why it blinks first, and is not always on.


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