What are the Symptoms of Dirty Fuel Injector? | What are the Causes of Bad Fuel Injector

A fuel injector plays a crucial role in the fuel injection system. It is most commonly used in nearly all modern car models. It is responsible for delivering fuel to the engine. Fuel injectors are designed to provide the optimal amount of fuel to the engine cylinders, ensuring efficient combustion. A faulty fuel injector can lead to numerous issues. This article describes the bad fuel injector symptoms, causes, and how to replace them.

What is a Fuel Injector?

A fuel injector is an electronically regulated valve that precisely distributes the right quantity of fuel into the engine cylinder or intake manifold. The powertrain control module (PCM) uses the data of the injector and measures the necessary fuel amount based on factors such as air-fuel ratio, temperature, speed, and engine load.

Fuel Injector

The primary function of a fuel injector is to deliver an ideal amount of air-fuel mixture to the engine cylinder for effective combustion. In doing so, it minimizes exhaust emissions, increases fuel efficiency, and enhances engine performance.

Fuel injectors are widely employed in diesel and gasoline engines, with their design and functionality varying according to the fuel type and engine in which they are utilized.

Symptoms of a Clogged or Bad Fuel Injector

The illuminated check engine light is one of the most common symptoms of a bad fuel injector. A bad fuel injector may also produce some other symptoms such as engine stalling, misfiring, excessive vibration, poor fuel economy, fuel smell, hard starting, engine knocking, or failed emission tests. 

Let’s discuss these symptoms of a clogged fuel injector in detail:

1) Check Engine Light Illumination

A blinking check engine light on your car dashboard is one of the most apparent symptoms of a potential issue with your fuel injector. If a fuel injector is dirty or clogged, it may not supply fuel to the engine efficiently, prompting a warning signal to alert the driver.

Check engine light

However, remember that the check engine light can also indicate other problems, so it is advisable to take your vehicle to a mechanic for a diagnostic scan.

To check your fault code memory at home, use an OBD2 code reader, which is relatively inexpensive.

2) Engine Stalling

A bad fuel injector may also cause engine stalling or rough idling at low RPM. Insufficient or uneven fuel supply causes the vehicle speed to drop less than the ideal level during idling, leading to a rough or even erratic idle. If your RPM falls very low, your vehicle may stall, requiring a restart.

Engine Stalling due to a clogged fuel injector

3) Engine Misfiring

Engine Misfiring

If a fuel injector is damaged, clogged, or dirty, your engine may misfire. This can negatively impact fuel efficiency, acceleration, and power output. Addressing this issue is crucial, as engine knocking can also occur, resulting in significant damage to the engine.

Read More: Engine Misfiring Causes and Symptoms

4) Engine Vibration

If your engine isn’t getting sufficient fuel, it may start to vibrate after completing a power cycle. In a turbocharged engine, a clogged fuel injector may have hazardous consequences, potentially leading to engine damage due to detonation.

Engine Vibration

During high RPM turbocharged operation, the engine needs a substantial amount of fuel, and if the fuel injector fails to provide it, detonation may be produced, which may lead to engine vibration.

5) Poor Fuel Economy

When the engine doesn’t receive the proper amount of fuel necessary for combustion, it demands more fuel from the injector. This leads to reduced fuel economy as your vehicle’s PCM overestimates the required fuel, resulting in unnecessary fuel consumption.

Poor Fuel Economy

6) Bad Fuel Odor

A noticeable fuel smell while driving is another clear symptom of a faulty fuel injector. This smell can occur if your injector is leaking or not closing properly. Whether it’s an external leak in the engine compartment or a leak into the exhaust pipe, both scenarios are dangerous, as they may cause the vehicle to catch fire.

Burning fuel Smell

7) Failed Emission Test

A change in the fuel injector’s spray pattern, resulting in either too much or too little fuel being injected into the combustion chamber, can also cause your vehicle to fail an emissions test.

Failed Emission Test, signs of clogged fuel injector

Excessive or insufficient fuel can increase emissions, preventing the catalytic converter from functioning effectively.

8) Hard Starting

A defective fuel injector may also make it challenging for the engine to start, particularly in a cold climate. This is because the injector might not deliver the appropriate amount of fuel required for the engine to ignite.

Hard Starting

9) Fuel Leak

A fuel leak in the engine compartment is one of the clear signs of a bad fuel injector. Fuel injectors are usually made of plastic. They can crack over time and cause an external leak. If you observe a fuel leak in the engine compartment, it is crucial to replace the affected injector promptly to avoid the risk of an engine fire.

Fuel Leak due to a leaked fuel injector

10) Engine Knocking

Furthermore, a faulty fuel injector may lead to engine knocking. A knocking noise is a metallic noise resulting from improper fuel combustion. If not addressed on time, this can lead to long-term engine damage.

Engine knocking Noise

Causes of A Bad Fuel Injector

The fuel injector goes bad or clogged due to one or more of the below-given reasons:

1) Contaminated Fuel

The contaminated or low-quality fuel may cause debris, dirt, or other foreign particles to accumulate within the fuel injector. These particles may clog or damage the injector over time.

2) Fuel Additives

Certain fuel additives may participate in deposit formation within the fuel injectors. While some additives help in cleaning the injectors, others may cause residue buildup and blockage.

3) Corrosion

Corrosion is one of the major causes of a faulty fuel injector. Moister or water in your fuel system may lead to internal corrosion in the fuel injector, damaging its components and reducing fuel delivery efficiency.

4) Prolonged Engine Idling

Prolonged engine idling may result in fuel vaporization, leaving deposits within the fuel injector. These deposits can build up over time and cause clogging.

5) Worn Parts

As time passes, a fuel injector’s internal parts may wear out or become damaged, affecting its capability to supply the appropriate amount of fuel and consequently impairing engine performance.

6) Fuel Varnish

Fuel breakdown can cause a varnish-like substance to form, particularly in cars that are not driven frequently. This substance may collect within the injectors, leading to clogs or poor functioning.

7) Poor Fuel Filter Maintenance

The fuel filters are used to trap solid contaminants before they reach the injector. If you don’t change or clean these filters regularly, they may become clogged, permitting solid dirt to pass through and damage the fuel injectors.

8) Insufficient Fuel Pressure

Inadequate fuel pressure may result in a malfunctioning fuel injector, as proper pressure is required for fuel atomization and delivery. This issue can stem from a clogged fuel filter or a bad fuel pump.

9) Electrical issues

Wiring issues may lead to the failure of the fuel injectors. If the injector does not receive the correct electrical signals from the powertrain control module (PCM), it may not function as intended.

Fuel Injector Location

Fuel injectors are usually located on the intake side of the engine, beneath the fuel rail, which is frequently mounted on the intake manifold.

In gasoline-powered vehicles, a fuel injector is almost always installed on the intake manifold, while in diesel vehicles, it is generally installed in the cylinder head.

Fuel Injector Replacement Cost

The replacement cost of the fuel injector varies according to the vehicle model, labor cost, and the type of brand.

The average replacement cost of the fuel injector is from $90 to $510. A fuel injector itself costs from $60 to $305, while the labor cost is from $40 t $205.

FAQ Section

What is the function of the fuel injector?

The main function of a fuel injector is to deliver an ideal amount of air-fuel mixture to the engine cylinder for effective combustion.

What does a bad fuel injector sound like?

A bad fuel injector can produce sounds such as engine knocking or pinging, which resembles a metallic tapping noise caused by improper combustion due to incorrect fuel delivery. Additionally, it may cause engine misfires, characterized by irregular or stuttering sounds during acceleration or idling.

What happens when fuel injectors go bad?

When the fuel injector goes bad, it produces different signs such as check engine light illumination, poor engine performance, engine stalling, misfiring, hard starting, engine idling, engine knocking, or fuel leaks.

How long do bad injectors last?

The lifespan of bad injectors can vary widely depending on the severity of the issue and driving conditions. Some can be expected to last between 80,000 and 100,000 miles. If a fuel injector is faulty or malfunctioning, it is important to address the problem as soon as possible to prevent further damage to the engine or other components.

Can I drive with a bad fuel injector?

Although it is technically possible to drive with a damaged fuel injector, it is not recommended, as it can cause the engine to run lean. This can lead to reduced performance, potential engine damage, and decreased fuel efficiency.

What are the signs of a clogged fuel injector?

  • Check engine light illumination
  • Engine stalling
  • Engine misfiring
  • Engine vibration
  • Poor fuel economy
  • Bad fuel odor
  • Failed emission test
  • Hard starting
  • Fuel leak
  • Engine knocking
Read More

Leave a Comment