Running your car near empty? – Here’s what can happen

As you drive long distances or get caught up in traffic, you may get that familiar orange warning light on your gauge cluster from time to time. Picture this, you’re nearing empty and your dash lights up a tiny spec of orange while you’re on the road either behind traffic or on the highway without a gas station next to you. Arguably, it’s a part of general vehicle maintenance, not only do you have to top up with the right kind of fuel, but you also have to top up with the right amount of fuel, and run with the right amount of fuel. 

You may think to yourself “I know my car,” or “she’ll make it,” or “I have a bit of reserve.” Whatever the case, and whatever the thought, it’s not as clear-cut as it is especially with modern cars and fuel pumps. There are a lot of people that mention never to run a car below a certain level because you could damage your car’s fuel delivery system. Your fuel system is also even more important if you run a diesel engine because most diesel fuel pumps run on high pressure in order to atomize the fuel better. That being said, let’s dive into why running close to empty all the time is bad for your car. 

The first threat that you don’t want to happen is running out of fuel far from a gas station, and far from home. Sure your car may run out while you’re going in a straight line, but what if there is a corner or a car behind you that isn’t paying attention? You may get rear-ended or into an accident. Let’s also not forget that many of the car’s controls are assisted, if not totally reliant, on the engine turning and running. 

Parts like the power steering pump or motor won’t work if your engine is not turning over. Your brake master cylinder is also helped along by the engine, and you won’t be able to disengage or modulate the brakes. Either way, having an engine die on you at high speeds is not favorable, so running out of fuel is a very dangerous situation to be in if you’re going fast. If you’re in traffic and you run out, you’re going to be a very annoying obstruction. 

Other components in your engine’s fuel delivery system will be affected because of the fuel pump. Consistently running your car close to empty or below ¼ on the fuel gauge could damage your car over the long term. 

The first item that comes into contact with your fuel, aside from your tank, is the fuel pump. This part ensures that a steady flow of fuel is readily available for the engine to inject or atomize into the combustion chamber. The pump pressurizes the fuel into the lines and lets a precise amount of fuel through the injectors. 

Running on a low fuel light will make your fuel pump experience unnecessary heat. Since fuel also cools down surfaces, it acts as a coolant in its own way. Without the necessary fuel surrounding the pump, it’ll get unnecessarily hot accelerating the wear and tear on the component. That’s not for all cars, as manufacturers can design their fueling system in a different way. 

Another hazard that isn’t always apparent is the accumulated sediment in your fuel tank. Your fuel pump has a filter that could get clogged with sludge and sediment that accumulated at the bottom of your tank, thus impeding the flow of fuel through your system and creating unnecessary heat and wear and tear. 

You could also introduce that sediment into your fuel system which can cause major damage. The first part to go will be your pump, then your lines, and finally the fuel injectors. Obstructions in this area will cause damage to the system and render your car unusable or with reduced performance. 

Finally, and in the worst-case scenario, you could cause lasting damage to your engine if your fuel system is compromised. Especially if your car is turbocharged or running high compressions, damaging your fuel system can lead your car to run lean. Because your engine needs a specific amount of fuel, problems can arise if your car isn’t being fed the right amount of fuel. Things like engine knocking can lead to bent valves or even damaged internals. While this is an extreme case, your engine will likely not turnover due to a faulty fuel pump rather than destroy itself due to a faulty fuel pump.