There isn’t a whole lot of new information to report here. In most cases, the well-established steps for dealing with a fuel-starved diesel engine are still completely valid. And thanks to advancements in diesel technology since the early 2000s, many of the physical tasks that were once necessary—such as manually priming the fuel system—are now handled automatically by the truck itself.
That said, it’s still essential to know what to do if your diesel pickup runs out of fuel. The best preventive measure is simply to monitor your fuel level closely. As long as the sending units, pumps, and other components of the fuel system are working properly, the fuel gauge remains your most accurate tool for tracking how much fuel you have left and estimating your driving range.
So, if — or more realistically, when — your truck does run out of fuel, what should you do? First and foremost, do not try to start the engine without fuel. Doing so can cause serious damage to the injectors and other components because they rely on fuel for lubrication.
Let’s start with older diesel setups — trucks like classic Ford models with the 6.9L IDI engine or first-generation Dodge Rams — which require some hands-on work to get running again. As you know, diesel engines operate under extremely high fuel pressure. When the system runs dry, air is sucked into the fuel lines, and that air must be vented, or “bled,” out before the engine can fire up again.
The first step is obvious: refuel the tank. Once that’s done, you’ll need to bleed the fuel lines and injectors. The process is similar to bleeding a brake system and can get a bit messy, depending on where the fuel-bleed bolt is located in the engine bay. Typically, you’ll need a wrench (size varies by model), a bottle or container to catch the primed diesel “blood,” and a few rags for cleanup.
Here Are the Steps
- For some mechanically fueled diesel engines, the best way to bleed air from the system is by loosening the fuel-line union nuts one at a time on the injection pump. Another option is to locate the bleeder screw—which is actually more of a bolt—usually found on the fuel-filter housing. In certain setups, this bleeder may be a Schrader valve in the fuel line. And on 2008–2010 Ford 6.4L Power Stroke engines, a specialized tool is required to bleed fuel through the fuel cooler.
- Loosen the bleeder (or union nuts) a few turns. Do not completely remove it/them.
- Using a compressor, apply air pressure into the fuel system through the filler neck, or crank the engine without starting it until a steady stream of fuel mixed with air bubbles exits from the bleeder. Avoid cranking the engine for too long, as this can overheat the starter or deplete the battery.
- Once all the air is out of the fuel system (no more bubbles), tighten the bleeder (union nuts or replace the bolt on a 6.4L’s fuel cooler).
- Attempt to start the engine. It should fire up.
Newer trucks — generally those built from 2000 onward — are much more self-sufficient when it comes to the priming process. Once you’ve added fresh diesel, the system can usually draw fuel to the engine in just a few minutes without you ever leaving the driver’s seat. After refueling, the basic steps are as follows:
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Prime the fuel system: Turn the ignition key to the Run position for about 30 seconds — but do not start the engine. This lets the electric fuel pump build pressure and push fuel through the system.
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Crank the engine: Turn the ignition off, then crank the engine for about 15 seconds. If it doesn’t start, repeat the priming and cranking steps (often called cycling the key) until the engine fires.
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Handle a quick stall: If the engine starts but immediately stalls, wait for one minute before trying again. Once it stays running, let it idle for several minutes and inspect for fuel leaks before driving.
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If it still won’t start: After multiple attempts, it’s best to have the truck towed to a qualified shop or dealership for proper diagnostics and repairs.
FAQ’s
How to get a diesel to start after running out of fuel?
First, refill the tank with clean diesel, then bleed any air out of the fuel system. Use the manual primer pump or cycle the ignition a few times to push fuel through before cranking the engine.
How to start a car when the fuel is empty?
You’ll need to refuel it first — cars won’t start without fuel. After adding gas or diesel, turn the ignition key to “ON” a few times without starting the engine to help the fuel pump pressurize the system, then try starting.
How to bleed a diesel engine after running out of fuel?
Locate the bleed screw on the fuel filter or injection pump and loosen it slightly. Use the primer pump or ignition cycling to push fuel until you see a steady, bubble-free flow, then tighten the screw and start the engine.
What is the fastest way to ungel diesel fuel?
Move the vehicle to a warmer place or use a diesel anti-gel additive. You can also apply gentle heat with a space heater near (not on) the fuel tank or fuel lines to melt the wax crystals.
Can you damage a diesel by running out of fuel?
Yes, running a diesel dry can introduce air into the system and strain the fuel pump. Repeatedly doing so can cause premature wear or even damage injectors and other fuel components.
How to restart a diesel engine?
After refueling, bleed air from the system and cycle the ignition several times to pressurize the lines. Once fuel is flowing again, crank the engine for a few seconds — it should start after a few tries.
Will diesel ungel on its own?
It will eventually ungel if the temperature rises above the fuel’s cloud point. However, in cold conditions, you’ll likely need heat or additives to get it flowing again quickly.
How to warm up a diesel fast?
Use a block heater or park the vehicle in a warm garage before starting. Once it’s running, let it idle gently for a few minutes to bring engine and fuel temperatures up safely.
How to start a gelled up diesel?
Warm the fuel system by moving the vehicle indoors or using safe external heat. Adding a diesel de-gelling additive can also help dissolve wax buildup and restore fuel flow.
Is it okay to try to start my car if it ran out of fuel?
It’s better not to — trying to start without fuel can damage the fuel pump. Refill the tank first, cycle the ignition to pressurize the system, then try starting.
How do you prime a fuel pump?
Turn the ignition key to the “ON” position for a few seconds without cranking the engine, then turn it off and repeat a few times. This builds fuel pressure before starting.
How to restart a car after running out of fuel?
Add fuel, wait a minute to let it settle, then cycle the ignition a few times before starting. If it still doesn’t start, you may need to bleed air from the fuel system, especially on a diesel.
Will a car start if it’s empty on fuel?
No — if the tank is completely empty, the engine won’t have any fuel to ignite. You’ll need to refuel it before it can run again.
What will happen if we run out of petrol and diesel?
Your engine will shut down once fuel supply stops. Running dry can also cause air to enter the fuel system, which may require bleeding before restarting.
How long does it take for your car to start after running out of gas?
It usually starts within a few seconds after refueling and cycling the ignition. In some cases, especially with diesel engines, it might take a few minutes and multiple cranks to clear air from the system.
How to start a diesel that ran out of fuel?
Refuel the tank, bleed air from the lines using the primer or bleed screw, and cycle the ignition several times. Crank the engine until it fires — it might take a few attempts.
How to bleed air out of diesel fuel system?
Open the bleed screw on the fuel filter or injection pump and use the manual primer or ignition cycling to push fuel through. Once air bubbles stop and a steady stream appears, close the screw.
How to start a diesel engine manually?
If the vehicle has a primer pump, use it to build pressure in the fuel system. After bleeding any air, crank the engine — if it’s old enough to have a decompression lever or hand crank, follow the manufacturer’s procedure carefully.
Is it bad for a diesel to run out of fuel?
Yes, it can be harmful. Air enters the fuel system, which can cause hard starting, rough running, or even damage to injectors and the fuel pump over time.
What to do when fuel is empty?
Safely pull over, turn off the engine, and refuel as soon as possible. After adding fuel, let it settle for a minute and cycle the ignition before trying to start the engine.
What to do when ran out of fuel?
Refuel the tank and allow the fuel system to repressurize by cycling the ignition a few times. For diesel engines, you may also need to bleed the fuel system before restarting.
How to start a dead diesel?
Check that fuel is present and the battery is strong. Bleed the fuel system, prime it, and crank the engine — sometimes it takes several attempts before it fires back up.
Why can’t you run a diesel empty?
Diesels rely on constant fuel pressure, and running dry introduces air, which disrupts combustion. It also risks damaging the high-pressure pump and injectors, which are expensive to replace.
How to prime a diesel engine?
Use the manual primer pump or cycle the ignition multiple times to push fuel through the lines. Once air is bled from the system and pressure builds, the engine should start normally.