Updated at: 29-03-2022 - By: micdot

This article contains affiliate links. Using any of the links on this page will allow me to earn a small commission at no additional cost to you. Your engine’s performance will suffer if you have an air leak in your diesel fuel system. If you’re having trouble pinpointing exactly where the leak is and what to do about it, we’re here to help.

You’ll discover how to locate a diesel fuel system air leak in this article. Also on the agenda is a discussion on how to remove air from a diesel fuel system  Detecting leaks might be difficult due to the fact that diesel fuel does not evaporate like gasoline and instead can build up in your system before leaking out.

Let’s get this show on the road!

Why Causes Air Leak In Diesel Fuel System?

A pump is used to move diesel from the tank to the injector in the diesel fuel system. Pumps struggle to propel liquid into engines if there is an air leak in their supply lines. This can lead to a blocked filter due to excessive pressure in the system. Cracks in lines at bends or welding joints are the most prevalent cause of an air leak. Your engine may struggle to run if you discover an air leak, which may have been caused by an incorrect filter or a worn gasket. Inadequate fuel supply is another potential cause of an air break (i.e., insufficient tank pressure).

Air leakage from the diesel fuel system can manifest in several ways. Out of the exhaust comes a cloud of reddish-orange smoke. Exhaust fumes spew out black smoke. Loss of power in the engine

What Can Happen When There’s Air Leak In Diesel Fuel System?

How To Find Air Leak In Diesel Fuel System

If your diesel fuel system is leaking, it can reduce your vehicle’s performance and cost you a lot of money to fix. In the event that you are experiencing any of these concerns, it is imperative that you take action quickly and not ignore any potential fuel system air leaks, as this can cause a wide range of complications.

Among them:

Driving a car that doesn’t operate well

Misfueling results in lower gas mileage and a lower return on investment. Damage to the engine may necessitate more costly repairs or perhaps a complete replacement. Despite the fact that diesel engines may not be damaged by air leaks in the fuel system, they can nonetheless be damaged over time. Checking your vehicle’s air leak on a regular basis might help you avoid similar issues in the future. Identifying an air leak in a diesel fuel system might be difficult.

Let’s find out right away!

How To Find Air Leak In Diesel Fuel System

How to locate an air leak in a diesel fuel system is next. A “bubble test” is a standard method for detecting air leaks in a diesel fuel system. Take the following steps:

Ensure that the fuel supply is replenished.

Begin the engine and let it run for at least an hour or more, depending on your preference. Look for rising bubbles in the fuel lines from the pump to the filter screen (usually near the filter screen). Take a peek inside and outside of your vehicle for bubbles, which signal that diesel is being expelled from the system.

The only way to find the source of the leak is to remove the gasoline lines and reinstall them in a different position. It is important not to produce any other leaks throughout the procedure, as the air leak could cover them up. Examine the engine to see if any new leaks have been discovered during the process of re-configuring the lines. If no additional leaks are discovered, the fuel lines should be returned to their original configuration and the search for leaks should resume with a bubble test or a visual evaluation of pressure properties (deteriorating vacuum). If you didn’t pressurize the system, that could explain why you didn’t find an air leak. There is no harm in temporarily connecting one of the auxiliary tanks to the test line and turning on all engines for about ten minutes before shutting them off, in case there is any uncertainty.

This should guarantee that all pump lines have acceptable pressures. Additional testing may be necessary to see if you have an air leak anywhere else in your system.

How To Bleed Air Out Of Diesel Fuel System

How To Find Air Leak In Diesel Fuel System

See how to remove air from a diesel fuel system in the following video:

A step-by-step guide on removing air from the diesel fuel system is provided below. Look for a loose or missing fuel filler cap. Whether everything appears to be in order, check to see if someone has recently inflated your tank. For several minutes, turn on the engine and let it idle. When you hear the hissing sound of air escaping from the injector valve, turn off the engine and inspect the injector for any damage.

If after a few minutes of idling you still hear a hissing sound, turn the engine off and on again. If you can hear or see bubbles coming from the gasoline filler neck area on top of the tank during idle times, keep doing this until there is no more air coming out of the injector valve or the tank.

How Do You Fix An Air Leak In Diesel Fuel System?

1. Seal the leak

As the initial stage in diesel fuel system air leak repair, machining must be used in order to plug the leak. With specialist tools, such as oxy-acetylene torches or other equipment designed to heat up sections of your fuel system where air has seeped inside, this is accomplished.

2. Plug it up

Plugging up the air leak is the next step in repairing the problem. Welding is a technique that employs high heat to join metal pieces on either side of a leak point in order to seal the tank and prevent leaks.

How to find vacuum leaks in your fuel system - YouTube


In order to avoid mechanical issues, you must do all in your power to locate and eliminate any air that may be present in your fuel system. Using this guide, you’ll learn how to locate and fix an air leak in your diesel fuel system. As a last resort, if you find the processes difficult, we recommend that you take your automobile to an auto mechanic for a thorough diagnosis and repair service.