8 Signs of a Bad Fuel Filter and What You Can Do About It

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Fuel filters are typically an overlooked part of an engine’s fuel system. But, the fuel filter plays an important role, and unfortunately, it’s hard to determine when it’s going bad.

Don’t worry; I’m here to clear up some of the confusion. In this post, I will go over eight signs that will help you determine if your fuel filter is bad.

Let’s get started.

1. Difficulty Starting Your Vehicle

If your car is having a hard time starting, this can be a sign of a bad fuel filter.

Your engine needs fuel to start. With a clogged or bad fuel filter, your engine won’t get enough fuel to run properly.

When your engine is not receiving enough fuel, your engine is trying to run on a lean-fuel combination.

A lean-fuel combination can result in your engine not starting, misfires, and difficulty starting.

2. Misfiring Engine

Clogged or bad fuel filters limit the amount of fuel that will reach your engine.

This causes a lean fuel-to-air mixture. When there is more air than fuel reaching your engine, this will result in your engine misfiring.

The downside of a clogged fuel filter is that misfires can happen at any time. Remember, fuel should be running to your engine constantly.

With a clogged fuel filter, if at any time while you’re driving, the flow of fuel mixture runs lean, your engine will begin to misfire.

If you experience random misfires, this is a sign that you have a clogged or failing fuel filter.

3. Reduced Engine Power

When your fuel filter is failing, this will cause a low fuel pressure. Low fuel pressure does not always cause misfires or issues with your engine starting.

In some cases, when your fuel filter is failing, it will cause your engine to underperform. A key sign that your engine is underperforming due to a bad fuel filter is a drop in your engine’s power.

You might notice that it takes more effort for your engine to reach its gears. You might also notice that you need to push down on your gas pedal harder to reach the same power level.

When this happens, it feels like your engine has suffered a decrease in horsepower.

4. Reduced Fuel Economy

One side effect of a failing fuel filter is reduced fuel economy.

If your fuel filter is not functioning properly, your engine will underperform. Two key signs your engine is underperforming are reduced engine power and poor fuel economy.

Clogged fuel filters reduce fuel economy for two key reasons:

  • Reduces quality of the gas in your engine
  • Your engine works twice as hard for the same work, which reduces fuel economy.

An easy way to determine if you are experiencing reduced gas mileage is refilling your tank more frequently.

This is especially easy to measure if you follow the same commute every day.

Let’s say you refill your tank every Monday. If all of a sudden you need to refill on Saturday, then this might be a sign of reduced gas mileage.

In newer vehicles, the gas mileage is displayed on your dashboard or the central display.

Keep track of this value over several weeks.

You can compare your MPG to the MPG recommended for your car’s specific year and model.

An easy way to determine your vehicle’s average gas mileage is using the U.S Department of Energy’s fuel economy website.

If your car does not display the MPG on the dashboard, you can use an app to track your MPG.

If your car has a lower MPG than the recommended MPG for your vehicle, I suggest you inspect your spar plugs.

5. Engine Stalling

If you continuously drive on a bad or clogged fuel filter, this can lead to your engine stalling.

Stalling typically occurs when your engine is not getting enough fuel or working too hard to get started.

With a bad fuel filter, your engine begins to overwork. In addition, the clogged filter lowers the fuel pressure and reduces the amount of fuel that will reach your engine.

These two situations together will cause your engine to stall.

6. Engine Stalling Frequently

If you continuously drive on a bad or clogged fuel filter, this can lead to your engine stalling.

Stalling typically occurs when your engine is not getting enough fuel or working too hard to get started.

With a bad fuel filter, your engine begins to overwork. In addition, the clogged filter lowers the fuel pressure and reduces the amount of fuel that will reach your engine.

These two situations together will cause your engine to stall.

Typically, once your engine starts stalling due to a bad fuel filter, the occurrences will only continue. If your engine starts stalling more frequently and all other parts of your vehicle are operating properly, this is a sign that your fuel filter is failing.

7. Check Engine Light Comes On

If your check engine light turns on, this can be a sign that your fuel filter is failing.

When your fuel filter is failing, it can cause many other issues with other parts of your fuel system and the engine, such as spark plugs, fuel pump, and fuel pump lines.

These can also trigger the check engine light to turn on.

The great thing is that you don’t need to guess why your check engine light turns on.

You can use a simple ODB scanner. Before, ODB scanners were overwhelming and hard to use. Now there are simple scanners and Bluetooth scanners that you can use.

One of the most common OBD codes to sign your fuel filter is bad is the P0087.

This is the code to indicate an issue that there are issues with your fueling system and pressure.

8. Failing Fuel Pump

A failing fuel pump is one of the most common side-effects of a failing fuel filter.

What happened is that when the fuel filter is not operating correctly, it puts additional stress on your fuel filter.

The result is that your filter will begin to wear out faster. In addition, to the additional stress, the poor fuel quality and particles in the engine will damage the fuel pump.

If you are experiencing issues with your fuel pump, you should also inspect your fuel filter. But, of course, the vice versa is true also. So, any issues with your fuel filter, you should also inspect your fuel pump.

What Does The Fuel Filter Do?

The fuel filters primary function is to clean the fuel before it gets it reaches the engine. The fuel filter ensures that no particles or unwanted items reach your engine. 

The fuel filter works by acting as a filter that all the fuel must run through before it reaches the engine. 

Fuel remains in the gas tank until the car is running. When the car is running the fuel line will begin to pump fuel through the fuel filter and into the engine. This will ensure that no particles reach the engine and keeps your engine clean. 

Frequently Asked Questions (FAQ's)

Should You Clean or Replace the Fuel Filter?

If you are having issues with your fuel filter, then you should always replace it.

All the fuel that enters your engine will pass through your fuel filter. So it’s always best to replace your filter then try and clean it.

Depending on the type of filter and the material used, you might not be able to clean your filter.

For example, nylon or paper-based fuel filters can’t be cleaned.

Since fuel filters can be as cheap as $50, it’s more economical for you to replace your fuel filter than to clean and use an ineffective and dirty filter.

What Happens If You Don't Change Your Fuel Filter?

If you don’t change your fuel filter frequently or once it’s gone bad, this can lead to engine damage and damage to the other parts of your fuel system.

One of the main issues with not changing your fuel filter is that it begins to allow debris to enter your engine. This debris can cause engine damage.

A damaged or bad fuel filter can also cause your fuel pump and fuel lines to begin to fail.

A failing fuel pump will increase the debris in your fuel. This will lead to additional stress on your engine and fuel system, causing them to fail and break down faster.

How Often Should You Change Your Car's Fuel Filter?

As a standard rule, you should change your fuel filter every 30,000 to 120,000 miles. However, the frequency with which you change your fuel filter will depend on the quality of the filter and the year of the car.

If you are driving an older car, such as those older than 2005, it should be changed every 30,000 to 50,000 miles.

Newer cars should be changed every 50,000 to 150,000 miles. Newer vehicles can typically be changed less often because filters are more effective.

Higher quality filters can last much longer than cheaper filters. These filters typically use more effective and durable materials that make them more effective.

Change lower quality filters more frequently. These filters typically use materials that wear down faster.

What Is the Fuel Filter Warning Light On?

The fuel filter warning light is an indicator that the fuel filter has collected sufficient water from the fuel.

Inside the fuel filter, there is a sensor that tracks the amount of water. Once the water is approaching the maximum water level, the warning light will turn on.

When the light turns on, this is a sign that it’s time to empty your fuel filter.

Some cars will automatically empty their fuel filter. If this is the case when the light turns on, it’s a sign that there was an issue draining the water.

Is it Safe To Drive When The Fuel Filter Warning Light Means?

Yes, you can drive with the fuel filter warning light. When the fuel filter warning light comes on, it’s not an immediate emergency.

The important thing is that you address the warning light within the next couple of days. After that, the water should be emptied to avoid water from getting inside the engine. If water gets inside the engine, it can cause serious issues.

It’s also important that you change your fuel filter at regular intervals.

How Much Does It Cost To Replace Your Fuel Filter?

The price of a fuel filter can vary from $10 to $100. The price to replace your fuel filter will depend on if you are replacing the filter yourself or if you will hire a professional. 

The average price for a fuel filter is around $25 to $50. Filters in this price range provide quality fuel filters at a reasonable price. 

Replacing a fuel filter is a relatively easy repair. For most mechanics, it will take less than two hours to complete. You can expect to pay between $50 and $150 for labor. 

The total cost to replace the fuel filter with a professional should be anywhere between $75 and $125. 

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