How To Clean a Fuel Filter Without Removing It

Fuel filters are very important, yet they are one of the most overlooked car parts. This filter is responsible for filtering out the fuel that comes from the gas tank and goes into the combustion chamber through the fuel injectors. Even though the fuel industry tries to produce as much clean fuel as possible, it is still too dirty for the engine. This is why fuel filters get clogged over time. Since fuel filters are in a hard-to-reach position, here is how to clean the fuel filter without removing it.

Key Takeaway

  • Get a fuel system cleaner by Techron, safety glasses, and gloves.
  • Clean the gas cap using a towel because most of the time, the dirt from the gas cap finds its way into the fuel system.
  • Clean the area around the fuel filler neck with a towel to prevent dirt from getting into the fuel tank.
  • Fill the fuel tank halfway.
  • Add 20oz of the fuel system cleaner into the fuel tank.
  • Continue to fill up the fuel tank all the way.
  • Drive at least 100 miles on the same day.
  • For best results, use a fuel system cleaner every 3,000 miles.

What Happens When The Fuel Filter Is Dirty?

How To Clean a Fuel Filter Without Removing It

A fuel filter is one of the most important components of a car, responsible for ensuring that only clean fuel enters the engine. The fuel filter works by trapping particles such as dirt and debris that could otherwise contaminate the engine, thus protecting its performance and longevity. It filters out these materials in two different stages.

First, the filter captures large solid particles during its primary state, preventing them from entering the fuel delivery system. Then, during a secondary stage, finer particles are removed before they reach the fuel injectors or carburetors.

When a vehicle’s fuel filter is dirty, gasoline contaminated with dirt and other contaminants can enter the fuel line and clog it, which reduces the flow of fuel to the engine. If the obstruction is serious enough, the car may experience problems with starting or misfiring while running.

Replacing the fuel filter in a car is an important yet often overlooked task when it comes to regular maintenance. The filter traps dirt, debris, and rust particles being pulled from the tank so that they don’t enter and damage the engine. Depending on driving habits, terrain covered, and quality of gasoline used, experts usually recommend replacing fuel filters every 25-30 thousand miles or 2-3 years.

How To Clean a Fuel Filter Without Removing It

How To Clean a Fuel Filter Without Removing It

Getting to the fuel filter and replacing it can be quite hard, even for experienced mechanics. This is why many car owners look for a way to clean the fuel filter without removing it. To be honest, even though I know how to replace the fuel filter, I was also looking for an easier way. Fortunately, I talked to a friend of mine who has worked on cars for the past 30 years and he gave me this guide on how to clean a fuel filter without removing it.

1. Required items

2. Clean the gas cap

How To Clean a Fuel Filter Without Removing It

When it comes to cleaning the gas cap, I literally do not know anybody that does this. Almost all car owners allow dirt and debris to build up on the gas cap. That dirt from the gas cap easily gets inside the fuel tank and contaminates the fuel. The more dirt there is in the gas tank, the faster the fuel filter will get clogged.

Grab a clean towel or a sponge and soak it in just lukewarm water. Clean the inside of the gas tank. Make sure to get all of the dirt from the threads. After cleaning it, make sure that it is completely dry. We do not want any water in the fuel system.

3. Clean around the fuel filler neck

How To Clean a Fuel Filter Without Removing It

Before we start cleaning the fuel filter, we first need to take a look at the fuel filler neck. Think of it like curing the disease and not the symptoms. If your fuel filter is dirty, there is a good chance that dirt and debris buildup from around the fuel filler neck has contaminated your fuel. Fuel from the gas station is dirty, yes. However, if you neglect the fuel filler neck area like shown in the photo above, disaster is just waiting to happen.

Clean the fuel filler neck while the gas cap is on because we do not want any more dirt in the fuel tank. Grab a sponge or a towel and soak it in lukewarm soapy water and clean the debris. Do not wipe inside the fuel filler neck because we don’t want any water or soap to get inside the fuel tank.

4. Fill up the fuel tank halfway

How To Clean a Fuel Filter Without Removing It

Before adding the fuel system cleaner, you need to fill the fuel tank halfway. It is best if you have the cleaner at hand while you are at the gas station. The reason why I always fill the fuel tank halfway before adding the cleaner is that when you continue to refill the fuel tank, you will mix the cleaner with fuel. So, whatever your fuel tank capacity is, fill it halfway.

5. Add the fuel system cleaner

How To Clean a Fuel Filter Without Removing It

The next step is to add the fuel system cleaner by Techron. If you are going to use a different product, make sure to read the instructions. Techron cleaner requires a full bottle (20oz) in one fuel tank. Once you add the cleaner, fill the tank all the way up.

The way the fuel system cleaner by Techron works is by attacking the harmful deposits that are clogging the fuel system. The cleaner has a unique formula that contains higher levels of active cleaners that will break the dirt and debris on the fuel filter and will unclog it. This is the best way to clean the fuel filter without removing it.

You do not have to drive your car long distances immediately. The fuel filter cleaner is in the gas tank and it will clean the fuel filter while you drive to work and back. Just make sure that you empty the fuel tank almost all the way down before refueling.

6. Use a fuel system cleaner every 3,000 miles

How To Clean a Fuel Filter Without Removing It

To always have a clean fuel filter, it is important that you clean it consistently. The fuel system cleaner by Techron is best if used every 3,000 miles. This way, you will ensure that no harmful deposits will build up on your fuel filter.

Symptoms of a Clogged Fuel Filter

The purpose of the fuel filter is to filter out the fuel before it enters the combustion chamber. Often, the fuel filter is located near the fuel tank. Due to their location, most car owners neglect their fuel filters which is very wrong. Over time, the fuel filter gets clogged and causes all kinds of problems. Here are some symptoms of a clogged fuel filter.

1. Check engine light

How To Clean a Fuel Filter Without Removing It

The fuel filter plays an important role in all modern vehicles. It is located along the fuel lines and has a mission to clean the fuel before it reaches the fuel injectors. Over time, the fuel filter gets clogged from dirt and debris found in the fuel, fuel filler neck, and gas cap. When it becomes clogged, it will restrict the flow of the fuel to the fuel injectors.

The fuel filter is not an electrical component and there is no specific code for a clogged fuel filter. However, a clogged filter will often throw a P0171 – Lean Condition trouble code which means the engine is getting more air and less fuel because the clogged fuel filter is restricting the flow of the fuel.

Hook up a scanning tool to your vehicle’s computer and scan it. If you see the P0171 trouble code, that is a good indicator that your fuel filter is clogged. Combine this symptom with at least one more symptom from this list to be sure that you are dealing with a clogged fuel filter.

2. Rough idle

How To Clean a Fuel Filter Without Removing It

A clogged fuel filter can cause a vehicle to experience rough idle and reduced power. The filter is responsible for allowing only clean, free-flowing fuel to reach the engine. When it’s clogged, fuel delivery is restricted and engine performance suffers.

The combustion process requires a steady stream of fuel in order to achieve optimal performance and a smooth idle. If the fuel is limited because of poor flow due to a clogged filter, the air-to-fuel ratio will be disrupted because there will be more air in the combustion chamber.

In order for an engine to run perfectly, it requires a perfect air-to-fuel ratio. The perfect air-to-fuel ratio is 14.7kg (air) to 1kg (gasoline) or 32 lbs of air for 2.2 lbs of gasoline. When the fuel filter is clogged, there is more air in the combustion chamber than fuel which leads to improper combustion and rough idle.

You will be able to tell that you have a clogged fuel filter if your vehicle has a rough idle especially when you try to rev the engine. When you press the gas pedal, the computer orders the throttle body to allow air into the system and tells the fuel pump to send fuel. However, due to the clogged fuel filter, there will be insufficient fuel to be burned into the combustion chamber and the vehicle will idle roughly.

3. Engine hesitation

How To Clean a Fuel Filter Without Removing It

Engine hesitation is a common issue experienced by drivers, typically when accelerating. When the engine does not receive enough fuel or misfires due to a clogged fuel filter, this results in the engine hesitating instead of running smoothly.

When you press down the gas pedal, the throttle body opens up to allow fresh air to enter the engine. The vehicle’s computer reads the amount of air that entered the engine and demands the appropriate amount of fuel to be sprayed by the fuel injectors. However, a clogged fuel filter will restrict the flow of fuel from the fuel tank into the fuel injectors causing the engine to hesitate.

This too can be checked by an OBD2 scanner. Connect the OBD2 scanner to the vehicle’s computer and look for a P0171 code. This code means that there is more air than fuel in the combustion chamber.

4. Crank but no start

A clogged fuel filter can be a common cause of a car that turns over but will not start. The role of the fuel filter is to ensure the fuel coming into the engine is clean and free from any impurities that could potentially cause damage or engine misfiring.

When the fuel filter becomes clogged, it restricts the flow of gasoline to the engine, leading to problems when starting as well as poor idle quality due to insufficient fuel available in the injector rail.

5. Engine stalling

When a fuel filter becomes clogged, it hinders the steady flow of clean fuel from reaching the engine. A clogged filter can cause the engine to run erratically, leading to such things as misfiring and stalling. Over time, dirt particles accumulate in the filter and its tiny pores become blocked.

This restricts the amount of gas that is able to reach the fuel injector, causing a decrease in fuel pressure for the engine which in turn causes reduced performance and eventually leads to stalling. As a regular part of vehicle maintenance, it is important to check and replace your car’s fuel filter every 20 000 kilometers or yearly (whichever comes first) in order to keep your car running smoothly.

6. Low fuel pressure

When the fuel filter becomes clogged, it restricts the flow of fuel and reduces the fuel pressure. This low fuel pressure affects how well the engine can run and will eventually cause problems if not addressed. Without enough fuel pressure to keep things running smoothly, cylinder combustion and other functions are affected as well.

Low fuel pressure also causes incomplete or erratic burning of the fuel which increases emissions, creates a misfire that reduces performance, or causes an overall loss in power. If left untreated, a clogged fuel filter can even result in complete engine failure.

Testing the fuel pressure in your car is a relatively simple job that requires the use of a fuel pressure gauge. The first step is to locate the Schrader valve, inscribed with the words “fuel injector” or “test port,” usually on one of the metal fuel lines near the engine. Once you have found this port, attach one end of the pressure gauge to it and open up your hood. Start your car’s engine and let it run for about thirty seconds, then take a reading from the gauge.

Check the owner’s manual to find out what exactly is considered normal fuel pressure for your vehicle.

Vide Polowenski

General Mechanic with over 20 years of experience specializing in General mechanics, exhaust systems, fuel systems, and fuse-related problems.

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