Running out of fuel might be annoying and even embarrassing, but it can also be bad for your car.
And despite our best plans, it does happen, so it’s worth knowing what to do and what not to do if you find yourself stuck with an empty tank.
In this guide, we’ll delve into what happens under the bonnet when you run out of fuel.
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When the tank’s left to run completely empty, the engine will start to draw in air along with the last dregs of fuel.
This air could stop the engine from starting again, as it throws the fuel-air mix needed for combustion way off kilter.
For this reason, it’s never good to let your car run totally dry, even if you know there’s a fuel station close by or have a can of spare fuel in the boot.
It puts the engine under a lot of unnecessary stress and could mean you struggle to get going again even after topping your car up, thanks to a build-up of air in the fuel tank and combustion chamber.
Behind the wheel
As your car runs out of fuel, there should be several tell-tale signs that it’s time to head to a petrol station to fill up.
Although you might think that the engine will simply stop running when the fuel tank reaches empty, this isn’t usually the case. Instead, your car will show signs of fuel starvation.
From behind the wheel, you’re likely to notice a drop in your car’s performance, but you might also experience intermittent power surges and engine backfiring or sputtering. The hydraulic power being fed into your power steering and brakes will also begin to die. While this won’t prevent you from steering or stopping the car, these functions will certainly require more effort to control.
However, cars with electric power steering shouldn’t have this issue since the power from your battery will ensure your steering continues functioning as normal.
From a mechanical perspective
Running out of fuel can play havoc with your fuel delivery system. Most modern cars are equipped with an electric fuel pump that sits inside the fuel tank. The fuel pump uses the fuel in the tank to cool and lubricate itself, but this task can become more difficult when your supply dips lower.
Allowing your tank to empty frequently can therefore lead to overheating issues with your car’s fuel pump. Ultimately, the fuel pump can fail due to low fuel levels, which is an expensive fix.
Engine damage isn’t always guaranteed when you run out of fuel. In fact, modern engines are built to withstand a lot more than simply running dry. Where the problems start, however, is if you drive an older car or if you regularly run out of fuel.
When a car’s low on fuel, it’ll draw anything in to keep itself going, including the debris and particles that build up at the bottom of the fuel tank. Older cars are particularly susceptible to pulling through debris, which is why you should get in the habit of never allowing the fuel level to sink too low.
If debris from the fuel tank is drawn into the fuel lines and directed towards the engine, it can lead to blockages in the filters which prevents the engine from performing at its best or even not starting at all. The sediment can be difficult to remove once it’s lodged in the fuel filter, which is why we’d always recommend adding a shot of Redex to help keep the system clean.
If you own a diesel car, you’ve probably heard the dangers (and potential expense) caused by running out of fuel.
That’s because the powerful fuel injectors in diesel engines start pulling in lots of air once there’s no more fuel in the tank, and this can have a catastrophic effect on different components within the system.
When the fuel system becomes completely clogged with air, it damages the injectors and filters, and can make it incredibly difficult to get the engine turning over again.
Unlike with a petrol engine, which will turn over with a couple of pumps of the accelerator after refuelling, getting a diesel going again may need a professional with the right tools.
For a diesel engine to start again after running empty, it’s often the case that air needs to be bled from the fuel system.
This can be an expensive and time-consuming process that should be left up to the professionals, as they’ll need to remove the filters, clean and blow out all the fuel lines, and potentially replace the injectors and pump.
If you drive a hybrid, you still need to think about your fuel, because running out of both fuel and electricity really would leave you stuck.
Now that you’re aware of the signs to look out for, you should be able to spot these while driving a car that’s running out of fuel. Any sputtering, misfiring, or issues moving off could all indicate that you’re running low on fuel.
The warning indicator light should pop-up on your dashboard if this is the case, but a quick check of your fuel gauge should let you know roughly how much fuel is left in the tank. Most modern cars also have a digital remaining mileage indicator, those these aren’t always accurate.
If you’ve caught it in good time, then you can calmly make your way to the nearest petrol station to fill up. However, in instances where you haven’t been so lucky, you’ll need to safely pull over, turn on your hazard warning lights, and assess the situation.
Is there a nearby petrol station within walking distance? If so, you might be able to buy the fuel you need, walk back to your car, and fill the fuel tank before setting off again.
If you’ve found yourself with an empty tank and you’re too far away from a petrol station to walk there, then the safest option is to call for assistance.
Whether you call a friend to come to your rescue with a transportable fuel tank or contact roadside assistance, ensure you stay safe while you wait. Staying inside the car is likely to be the safest option if you’re parked on a quiet street. However, you should wait safely behind a barrier or away from traffic if you’ve stopped on a dual carriageway or motorway.
When you’ve safely refuelled your car and need to get the engine running again, there are a couple of things you can do to make sure the engine fires without putting too much strain on the ignition, starter motor and battery.
It can take a few tries to get the engine going because the fuel hasn’t circulated through the system, so it’s a good idea not to crank the ignition over and over again, as this will only drain the battery.
Here are a few things to try to get the engine running:
- Press the accelerator pedal to engage the fuel injectors more quickly. This will get the fuel circulating through the engine to help the car start.
- Turn the ignition to the ‘on’ position without starting the engine. Doing this a couple of times will allow the electric fuel injectors to begin circulating fuel without a high demand for power being placed on the battery.
- Make sure the car has had plenty of time to cool down. Running out of fuel could cause the fuel pump to overheat and fail, and it may take a while for this to drop back to a normal operating temperature, even after refuelling.
You might think that the odds of running out of fuel are slim. But, these things do happen, especially if you get stuck in bad traffic for a long time.
The best thing to do is to be prepared, so if you’re going on a long journey or it’s bad weather make sure you’re fully topped up.
We’d also advise you to always keep your fuel tank topped up to at least a quarter full.
That way, the engine is only ever drinking clean fuel, and not the dirty stuff at the bottom of your tank.
Although it can put you in a sticky situation, there aren’t any legal repercussions for running out of fuel while driving on roads in the UK. The law states that running out of fuel is an acceptable reason for using the hard shoulder and receiving emergency assistance on the motorway.
While this is the case, you should still be checking on your fuel gauge before starting any journey. Motorists can still be fined for careless and inconsiderate driving if their car is causing an obstruction. Since it’s seen as a completely avoidable occurrence, you could be hit with an unlimited fine and points on your licence.
So, while it might not be illegal to run out of fuel while driving, it isn’t necessarily a good idea to do so.
In addition, you might want to brush up on the laws of other countries if you’re thinking of taking a road trip abroad. Other countries, including Germany, do have penalties for running out of fuel on some major roads.
For more information and to browse our complete range of innovative fuel additives, visit the Redex homepage today.