Air in Fuel System Symptoms: Gasoline & Diesel Engines!

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Air in Fuel System Symptoms

If you’re wondering what air in fuel system symptoms is, don’t worry. I’ll show you a few tell-tale signs that illustrate the seriousness of this problem. This blog post will help you understand what the symptoms are and how to identify whether or not your vehicle is suffering from the air in fuel system problems.

Air in fuel system symptoms varies, depending on the types of engine: gasoline or diesel engines. Your engine may experience low power, misfiring, or vibration. 

Air in Fuel System Symptoms in Gasoline Engines

Gasoline engines commonly experience the following:

  • Sputtering and backfiring: The misfiring and low-power symptoms can be caused by air in the fuel system, which creates a leaner fuel or air mixture that results in more backfiring.
  • These happen because the fuel and air mix is not balanced with enough fuel. The backfiring noise occurs as a result of the explosion caused by the misfire.
  • Poor throttle response: Fuel and air mixes with too much nitrous oxide (N02) can create poor throttle response by reducing the engine’s ability to deliver power effectively.
  • Fuel system components can be damaged due to increased pressure created by increased air moving through the system, but it mainly affects other parts in the fuel system.

Air in Fuel System Symptoms in Diesel Engines

Diesel engines commonly experience the following:

  • Vibration: The high-rotational centrifugal force caused by air in the fuel system can cause a vibration of the engine. Even if the engine is idle, this vibration will occur because of unbalanced fuel and air mixes.

Vibration can cause accelerated wear of all parts of the fuel system, including fuel filter, injection pump piston and injectors. It can also cause premature wear of engine mounts and driveshafts.

  • Poor engine performance: There is a leaner fuel and air mixture caused by air in the fuel system, which in turn causes poor combustion and reduced throttle response. This also results in poor acceleration.

Idling can become difficult because of unbalanced fuel and air mixes. The idle quality keeps fluctuating when it should be fixed at one point.

  • Engine knock: Diesel engines used in trucks and buses are more susceptible to this problem because of the higher heavy-duty demand on diesel engines. When air enters the fuel system, it can cause detonation. If this happens, the engine’s performance is reduced because of poor combustion and reduced throttle response.
  • Oil consumption: There is more air in the diesel engine than in the gasoline engine, which causes increased air pressure that compresses oil (oil is slippery). This causes oil consumption that is caused by damaged fuel system components.

What Causes Air Getting into The Fuel System?

There are a few things that can cause the air in the fuel system:

1. Engine oil leaks

If there is a leak in the engine oil system, it can allow air to get into the fuel system. The high pressure of the leak will cause pressure build-up in the other parts of the fuel system. If you hear an unusual noise coming from your engines, such as metallic noises and banging noises coming from your engine, this means that there is a leak.

Why does this happen? The turbocharger frequently receives high-pressure flammable gases. These gases are pressurized to improve the engine’s power. If the engine oil becomes contaminated or dilutes, it can result in poor sealing of the gaskets creating excess oil leakage.

2. Fuel leaks

Diesel engines are more susceptible to fuel leaks because of their nature. Diesel engines are frequently used in trucks and buses, which are subjected to frequent bumps and vibrations during transportation. This puts extra pressure on the engine’s fuel system, which can cause leaks in the lines, hoses, and seals.

Air can also come from a cracked or damaged air bubble in a fuel line. This is a common problem among vehicles with electronic fuel injection systems.

3. Refueling

Air can enter the fuel system during refueling. Potential sources for this include bad connections at the gas pump and scavenging of air from the atmosphere by oxygen sensors or other components that are sensitive to air.

Air can also enter the fuel system when the tank is overfilled, which results in the deformation of the fuel tank’s sump. This problem can lead to many issues within the fuel system.

How To Bleed Air Out of The Fuel System

The first step you need to take is to start the engine and let it idle for a few minutes. The purpose of this is that the engine’s fuel system components will be heated up by the flow of fuel that will allow them to expand. This expansion occurs because the oxygen content in the air increases as it heats up.

This can remove excess air from the fuel lines and injectors. Do not rev the engine during this process, since you will throw a wrench into your entire system.

When the engine is warm, you can put a wrench on one of the lines or injectors and open it up until you hear a “clack” sound. This means that the line is air-tight and air will not enter it anymore. Repeat this step for all of the lines and injectors of the fuel system.

If this does not work, you need to take the vehicle to a mechanic. If your engine is still plagued by air in the fuel system, you should hire a professional mechanic to inspect the problem. It’s important that you hire someone who has experience working on vehicles like yours.

Final Words

When you see any of the air in fuel system symptoms as mentioned above, your engine is plagued by air in the fuel system, try to fix it if you can or you can take it to a reputable mechanic. The best thing you can do is to prevent the problem by doing good preventive maintenance. Make sure that all of your fuel system components are sealed and not leaking, especially the gaskets holding them together.