How To Start A Diesel Truck That Has Been Sitting [5 Easy Solutions]

It’ll be difficult to start your truck if it has fuel contamination, a clogged air filter, a lack of oil, unpowered batteries, or injector issues.

These issues can be easily fixed by following the right steps. You’ll learn how to start a diesel truck that has been sitting for a long time in this guide.

How To Start A Diesel Truck That Has Been Sitting [5 Easy Solutions]

There’s a slight chance that your diesel truck may start immediately even if it has been sitting for a while. Put your key in and wait for the glow plugs to heat up. The light on your dashboard will turn off when the glow plugs are ready to use. Start the engine and see if your truck moves.

There could be a few reasons that stop your engine from starting. We’ll take a look at what these reasons are and how you can fix them. Let’s learn how to start a diesel engine that has been sitting for a while.

Note: You can also read how to load a non running car on a tow dolly

1. Fuel Contamination

Diesel is an organic mixture that allows bacteria can grow in it. It attracts moisture from the air. Diesel reacts with the air and water is produced. The diesel fuel that has been sitting for a while will make the perfect breeding ground for bacteria.

The bacteria can reach the injection pump and destroy it. The injection pump is generally the most expensive part of the engine. Let’s hope that your injection pump hasn’t been damaged.


Drain the fuel completely before you attempt to start the engine. The right way to fill up the fuel is to fill it up to that tank. Make sure that no air can pass through to the fuel.

Add biocide to your diesel as a preventive measure. It’ll keep bacteria from growing in your truck. You need to replace the diesel if you’ve stored it for more than six months.

If the bacteria have reached your injection pump, you’re screwed. It’ll cost you a fortune to replace it. But you don’t have a choice. You’ve to replace the injunction pump if you want your truck to be up and running again.

2. Clogged Fuel Filter

Your truck’s fuel filter can become clogged if the truck has been left idle for a long time. A clogged fuel filter will deteriorate the flow of fuel in your truck.


Replace your old fuel filter with a new and clean one. Make sure that you keep changing your fuel filter after every 20000 to 40000 miles of driving.

3. Lack Of Oil

The diesel must have reached the bottom if you left the truck sitting for too long.  The truck won’t be able to run properly without engine oil.


You have to put new oil in the truck. Drain the remaining oil before you out the new oil. Take out the glow plugs before you pour the new oil. Crank the engine for thirty seconds after you’ve added the oil. 

The goal here is that the oil pump lubricates all parts of the engine. You can repeat this step a few times to make sure that the oil spreads to all parts of your engine.  Be sure not to crank your engine for more than thirty seconds at a time.

4. Unpowered Batteries

Your batteries may have already lost charge if the diesel truck has been sitting for too long. A diesel truck can’t run without batteries.


It’s important to have fully charged batteries when you’re trying to start a truck that hasn’t run for a long time. Starting such a truck requires more energy than usual. Buy new batteries and then start the truck.

5. Injector Issues

A diesel engine requires a lot more pressure than a gasoline engine. You need to make sure that your injectors are running at the right pressure. You’ll see white fumes if your injector is dirty.

You’ll know if your injectors have gone bad by checking the glow plugs or the temperature of the cylinder. You’ll notice black smoke coming out of your engine if your injector is leaky.


You can solve your injector issues by cranking the engine. Add some MMO to your cylinders and let it sit overnight. It’ll help you to crank the engine. Wait for a day and crack the fuel lines in your injectors the following day.  Crank the engine until the fuel leaks out and clean the line to the injector union.

Make sure that the oil goes out of the cylinder before you start cranking the engine. Removing the glow plugs will help you crank the engine quicker.

If you can’t remove the glow plugs safely, ask for help from someone who can do it. Tighten the fuel lines and put the glow plugs back. Your engine should fire up if there are no serious issues.

You must crank the engine in small bursts. Don’t crank the engine for more than thirty seconds at a time. There’s a possibility that you’d fry the starter if you crank the engine for too long. Now you know how to start old diesel engine.


How long can a diesel car sit without being driven?

A diesel car can sit anywhere between six months to one year without being driven. Leaving a diesel car unattended longer than that can cause the build-up of bacteria in your car.

How to start a diesel truck in the cold?

It’s hard to start a diesel truck in the cold due to gelled fuel and electric failure. To prevent the fuel from freezing, warm it up for enough time or store your truck in a warmer area.


You’ve learned how to start a diesel truck that has been sitting for a while in this guide. We’ve covered the most common causes why your truck won’t run and provided the solutions. If these tips aren’t working and your truck is still not running, talk to a technician.

We hope this guide has helped to start your diesel engine and run your truck. Let us know if this post has helped you by leaving a comment below. Reach out to us if you have any questions!

About John M

John contributed as a technical head at an automobile company just 2 years after his post-graduation in Automobile Engineering. He loves to lead a free life, so he left his job & started blogging. Now, he does research on every automotive problem, part & product and seeks a better solution & best products & shares his findings with his readers to help them as well as to minimize their struggle.

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