24/11/2006
Running out of fuel is a motorist's nightmare, often striking at the most inconvenient times. While it might seem like a simple oversight, the complexities of modern car engines and their sophisticated fuel systems mean that simply pouring in a few litres isn't always enough to get you going again. Unlike older vehicles with carburettors, today's cars almost universally rely on fuel injection systems, which require a specific approach when the tank runs dry. This guide will walk you through the essential steps to safely restart your vehicle, minimise potential damage, and understand why these steps are crucial for your fuel-injected car.
Most vehicles manufactured after the mid-1990s are equipped with a fuel injection system, making this advice highly relevant for the vast majority of drivers on UK roads. If your car is relatively new, it almost certainly has one. This system uses an electric pump to deliver fuel under pressure to the engine, a significant departure from the gravity-fed or mechanical pump systems of yesteryear. Understanding this difference is key to a successful restart. Let's delve into the process.
The 5-Step Process: Getting Back on the Road
Step 1: Refuel Your Tank Safely and Adequately
This might seem obvious, but it's the fundamental first step. Your car needs fuel to run, and when the tank is completely empty, you'll need to add some. While you don't need to fill the tank to the brim, a minimum of five to ten litres is generally recommended. This amount provides enough volume to overcome any air pockets in the fuel lines and gives the fuel pump something substantial to work with.
It's always a sensible idea to carry a certified 'Jerry Can' in your boot for such emergencies. These robust containers are specifically designed for safely transporting fuel. If you don't have one, you'll need to find a way to get to the nearest petrol station. Once you have the fuel, ensure your vehicle is in a safe location, ideally off the main road, with hazard lights on. Carefully pour the fuel into your tank, making sure you use the correct fuel type for your vehicle (petrol or diesel). Using the wrong fuel can lead to severe and costly engine damage.
Step 2: Allow the Fuel to Integrate and Prime the System
The fuel system in a modern car is not a simple, straight pipe. It's a complex network of lines, filters, and valves designed to deliver fuel precisely. When you run out of fuel, air can enter these lines, creating 'airlocks' that prevent the new fuel from reaching the engine. Therefore, simply adding fuel isn't always enough; you need to help it move through the system.
First, ensure your vehicle is on as level ground as possible. If you're on a slope, try to push it to a flatter spot. This helps the fuel settle and flow more easily. Next, before attempting to start the engine, prime the system. This often involves turning the ignition key to the 'on' position (where the dashboard lights illuminate, but the engine doesn't crank) for a few seconds, then turning it off. Repeat this process three or four times. This action often activates the electric fuel pump, which will begin to push fuel through the lines and expel trapped air.
It's vital to be patient here. Do not immediately try to crank the engine. Giving the system time to draw fuel and push out air significantly increases your chances of a successful start and prevents unnecessary strain on your battery and starter motor.
Step 3: Engage the Fuel Injectors and Pump
This step is crucial for fuel-injected vehicles. As mentioned, these cars use an electric fuel pump, typically located in or near the fuel tank, to pressurise the fuel lines. When the tank runs dry, this pump might struggle to draw fuel and can become 'dry'.
To properly engage the pump and ensure fuel reaches the injectors, follow this procedure: Turn your ignition key to the 'accessory' or 'on' position (just before the engine cranks). You should hear a faint whirring sound from the rear of your car – this is the fuel pump activating. Let it run for about 10-15 seconds, then turn the key off. Repeat this cycle three or four times. This allows the pump to build up sufficient pressure in the fuel lines and ensures that the fuel injectors themselves are primed and ready to atomise the fuel into the combustion chambers.
Crucial Note: Do not crank the engine during this step. The aim is to prime the system, not to start the car. Premature cranking can drain your battery unnecessarily and may not allow the system enough time to properly pressurise.
Step 4: Attempt to Start the Car
By this point, the fuel system should be sufficiently primed, and fuel should be available at the engine's combustion chambers. It's now time to try starting the car. Turn the key fully to the 'start' position. Don't be surprised if the engine splutters a few times or takes slightly longer than usual to catch. This is normal as any remaining air is purged and the engine stabilises.
If the car doesn't start after a few seconds of cranking (no more than 5-10 seconds), release the key and wait for a minute or two before trying again. Avoid continuously cranking the engine, as this can quickly drain your battery and overheat the starter motor. If it still refuses to start after two or three attempts, revert to Steps 2 and 3. It's possible that more air needs to be bled from the system, or the fuel pump needs more time to build adequate pressure.
Most of the time, following these steps patiently will result in the car starting. Once it does, let it idle for a few minutes to ensure the fuel system is fully stable before driving off. Head straight to the nearest petrol station to fully refill your tank.
Step 5: When All Else Fails – Call for Professional Assistance
Despite your best efforts, sometimes a car simply won't restart after running out of fuel. This could be due to a persistent airlock in a particularly tricky part of the fuel system, or it might indicate a more serious underlying issue that was exacerbated by running dry. For instance, repeatedly running out of fuel can put a significant strain on the electric fuel pump, potentially leading to its premature failure.
If you've diligently followed the previous steps multiple times and your car still refuses to start, it's time to call for professional roadside assistance. Continuing to crank the engine in futility will only drain your battery, leaving you in an even worse predicament. Most car manufacturers offer roadside assistance, or you might have a policy with a private breakdown service. Having their contact number readily available is always a good idea.
Understanding Fuel Injection: How Do I Know My Car Has It?
As mentioned, the vast majority of modern cars are equipped with fuel injection. If your car was manufactured after the mid-1990s, it's almost certain to have it. Older vehicles (typically pre-1990s) might use carburettors, but these are now quite rare on the roads. The key difference lies in how fuel is delivered to the engine:
| Feature | Fuel Injection System | Carburettor System (Older Cars) |
|---|---|---|
| Fuel Delivery Method | Electric pump pressurises fuel, delivered via injectors. | Venturi effect (airflow) draws fuel into engine. |
| Starting After Running Dry | Requires priming the electric pump to clear air. | Often just needs fuel, may require manual priming pump. |
| Engine Management | Electronic Control Unit (ECU) precisely manages fuel. | Mechanical, less precise fuel-air mixture. |
| Commonality | Virtually all modern cars. | Rare in cars post-1990s. |
If you're unsure, consulting your car's owner's manual will confirm the fuel system type. However, for most drivers of contemporary vehicles, assuming you have fuel injection is a safe bet, and therefore, these steps are directly applicable.
Preventing Running Out of Fuel: Best Practices
Prevention is always better than cure. Here are some tips to avoid finding yourself in this predicament:
- Monitor Your Fuel Gauge: Sounds simple, but don't let it dip below a quarter tank, especially before long journeys or in unfamiliar areas.
- Know Your Car's Range: Understand approximately how many miles you can travel on a full tank.
- Plan Your Journeys: Identify petrol stations along your route, particularly on motorways or in rural areas where they might be sparse.
- Don't Rely on the 'Miles to Empty' Display: While helpful, these estimates can be inaccurate, especially in varying driving conditions.
- Carry a Jerry Can (Empty): While you shouldn't carry a full one routinely due to safety, having an empty, approved jerry can means you're prepared to collect fuel if needed.
Potential Complications and FAQs
Can running out of fuel damage my car?
Yes, it can. The electric fuel pump relies on fuel to lubricate and cool it. Running dry can cause the pump to overheat and fail prematurely, which is an expensive repair. Additionally, if the engine misfires repeatedly during attempts to restart, it can send unburnt fuel into the catalytic converter, potentially damaging it.
What if my battery is flat from trying to start the car?
If your battery is drained, you'll need a jump start from another vehicle or a portable jump starter. Once the car is running, the alternator will recharge the battery, but it's best to drive for at least 30 minutes to ensure a good charge.
How long does it take for the fuel to reach the engine?
After adding fuel and priming the system, it usually takes a few minutes for the fuel to travel through the lines and for the pressure to build up. This is why patience is key during the priming steps.
Is it safe to push my car to a petrol station?
Pushing a car, especially a modern one, is generally not recommended due to its weight and the potential for injury. It's safer to have someone bring fuel to you or call for roadside assistance. If you must move it a very short distance, ensure it's on level ground, you have sufficient help, and the steering is unlocked.
What's an airlock and how do I deal with it?
An airlock occurs when air becomes trapped in the fuel lines, preventing the flow of liquid fuel. The priming steps outlined (turning the key to 'on' multiple times without starting) are designed to activate the electric fuel pump, which pushes this trapped air out of the system, allowing fuel to flow freely.
Safety First: When You're Stranded
If you do find yourself out of fuel, your immediate priority should be safety:
- Pull Over Safely: Move your vehicle to the hard shoulder or a safe lay-by as soon as possible.
- Hazard Lights: Turn on your hazard warning lights to alert other drivers to your presence.
- Hi-Vis Vest: If you need to exit your vehicle, especially on a busy road, wear a high-visibility vest.
- Warning Triangle: Place a warning triangle a safe distance behind your vehicle (usually 45 metres on a road, or as per legal requirements).
- Stay Safe: If on a motorway, wait behind the safety barrier if possible.
Running out of fuel is an inconvenience, but with the right knowledge and a methodical approach, you can often get your vehicle restarted without professional help. Remember the steps, be patient, and always prioritise safety. Happy motoring!
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