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Most Common Bad Fuel Injector Symptoms

ByTsukasa Azuma-June 25, 2024

Any issue with it will badly affect the engine performance and may make it difficult to drive. It is necessary to detect bad fuel injector symptoms before your precious car gives up suddenly.

Vehicles manufactured before the 1980s were equipped with a carburetor. But, automobiles these days have the advanced electronic fuel injection system instead. Being a part of this system, a fuel injector does the job of spraying fuel into the engine.

What does a fuel injector do? Well, it supplies the engine with fuel to help with the internal combustion process. It sprays fuel into the engine’s cylinder via a nozzle. 

The Engine Control Unit (ECU) monitors the injector’s function and makes sure that it sends the right amount of fuel to the engine at the right time.

Bad Fuel Injector Symptoms

Fuel injectors are unlikely to malfunction if you clean them regularly. When you are not on top of the maintenance, it can get clogged with dirt and fail completely.

What happens when fuel injectors go bad? It definitely affects the engine performance. 

A bad fuel injector will mess up either with the amount, timing, angle, pressure, or pattern of the sprayed oil. Either way, the car won’t operate the way it should be.

Here are some common symptoms of bad fuel injector:

Engine Performance Issues

Fuel injectors not working properly means the engine does not get enough fuel sprayed onto it. 

As a result, the combustion process does not kick off, causing the engine to misfire and creating several performance-related problems like struggling to accelerate, pausing after pressing down the gas pedal and yielding lower fuel economy.

Fuel injectors not working properly means the engine does not get enough fuel sprayed onto it. (Photo: Mechanic Base)

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All these problems happen due to the incorrect air/fuel ratio. A delay, in this case, will lead to overheating and even stalling the engine.

Rough Idling

Due to the incorrect amount of fuel into the engine, the vehicle’s RPM falls below the optimal level when idling. As a result, it starts doing rough or convulsive idling. The engine can halt too if the RPM level drops too low.

Engine Vibration

The sprayed fuel from the injectors assists with the combustion process. When one of them is faulty, its corresponding cylinder will be unable to fire. The aftermath is the constant hiccup or vibration of the engine at the time of driving.

Vibration is one of those bad fuel injector symptoms that match to many other engine issues stemming from other sources. Diagnose the fuel injector system to make sure that the problem is with the injectors.

Check Engine Light Comes On

After all these engine troubles, it only makes sense that a malfunctioning injector will trigger the check engine light. 

The ECU sets off the light upon sensing an anomaly like engine misfire, clogged injectors, or an electrical issue.

Fuel Leak

Due to old age, the fuel injector may develop a hole or get damaged. The oil will leak out of the opening when this happens, making it leak from the injector’s body. 

It could come from the injector’s seal tool, which will only worsen over time. A visual inspection is enough to discover the trace of gasoline on the injector’s surface or on the fuel rail.

Smell Of Fuel

A chain reaction of fuel leak will be fuel odor. It is either a leak in the injector or its seal, you are going to smell gasoline. 

It happens because the oil is not getting burned as the injector does not function properly. A faulty sensor or fuel lines can also be the culprits. 

No matter what the reason is, any sort of gasoline odor should be addressed right away, lest they turn into a huge safety hazard.

Failed Emissions Test

The bad fuel injector symptoms also include excessive emission due to incomplete or irregular burning of the gasoline. A leak in the injector can make the air/fuel ratio so rich that it can burn the catalytic converter.

Fuel injectors are vital in the operation and driveability of a car. You should take the car to a professional mechanic if it shows any of these signs mentioned above.

The bad fuel injector symptoms also include excessive emission due to incomplete or irregular burning of the gasoline. (Photo: ceat.com)

Solutions And Repair Costs

Majority of injector symptoms occur due to not cleaning them regularly. It is easy to prevent the clogging if you do the cleaning at every 30,000 miles. 

A bottle of cleaner does not cost more than $15. A professional service may charge $50 to $100 if you need deep cleaning for extremely dirty injectors.

You’d be glad to know that cleaning is the solution to most problems of bad fuel injectors. Or, you may need to change the O-rings in case there is a leak. 

Sometimes, replacing the injectors is the only way, which will set you back for approximately $800 to $1,500.

FAQs

1. How can I tell if one or more fuel injectors are failing?

You can detect a failing fuel injector by paying attention to the symptoms mentioned above. Additionally, a diagnostic scan tool can help identify which specific injector(s) may be causing issues.

2. What is the cost of replacing a fuel injector?

The cost of replacing a fuel injector can vary depending on your vehicle’s make and model, the number of injectors needing replacement, and labor costs. Generally, it can range from a few hundred to over a thousand dollars.

3. Is it safe to drive with a bad fuel injector?

While you can technically drive with a bad fuel injector, it’s not advisable as it can lead to reduced engine performance, lower fuel efficiency, and potential engine damage. It’s best to address the issue promptly.

4. Are all fuel injectors in my vehicle the same, or do they vary by cylinder?

In most vehicles, the fuel injectors can vary by cylinder, meaning each cylinder has its own injector. However, some older or simpler engine designs may have a single injector for all cylinders.

5. What are the signs of a fuel injector leak?

Signs of a fuel injector leak may include a strong smell of gasoline, visible fuel leaks around the injector, poor fuel economy, and potentially hydrolock (if fuel leaks into the cylinder)

6. Can a fuel injector cause my engine to stall or hesitate?

Yes, a failing fuel injector can cause engine hesitation, stumbling, or even stalling because it disrupts the proper air-fuel mixture required for combustion.

Check out this video from haile auto garage to learn how can we clean the injector nozzle of our car by ourselves!

Final Words

In conclusion, understanding the most common bad fuel injector symptoms is essential for maintaining your vehicle’s performance and efficiency.

Fuel injectors play a crucial role in delivering the right amount of fuel to the engine for combustion. When they start to fail, it can lead to a range of issues that affect your vehicle’s overall performance.

Tsukasa Azuma is an awesome car blogger of Car From Japan. He owns a car repair shop at downtown Osaka, and he put all that experience to good use in his sharing posts. Tsukasa’s blog is one of the best resources for information about keeping your favorite imported car running smoothly. Moreover, because of being passionate to learn about the recent happenings in auto industry, he doesn’t only provide great car maintenance tips, he also always updates latest trends in among car brands and share them in his own interesting viewpoint.

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