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8 Signs Of A Failed Fuel Injector

August 17, 2020

8 Signs Of A Failed Fuel Injector

Your vehicle is built with a variety of intricate parts. As a vehicle owner it’s impossible to be familiar with every part and purpose. If your vehicle has been diagnosed with a failed fuel injector and you are trying to learn more about this part of your vehicle, we are here to help! In this blog we will discuss the purpose of your vehicle’s fuel injector, 8 signs of a failed fuel injector and answer frequently asked questions associated with a failed fuel injector.

What is the purpose of a fuel injector?

The basic function of a fuel injector is to supply your vehicle’s engine with fuel. The injector sprays “injects” fuel into the cylinder of the engine through a nozzle so that the internal combustion process can begin. The fuel must be delivered at the right time, amount, pressure, angle and spray pattern.

The Engine Control Unit (ECU) makes sure the injector sprays fuel at the right time and in the right amount so the correct air/fuel mixture is created. The ECU is your vehicle’s central computer or “brain” that manages different parts, including the fuel injector.

It also determines when fuel is needed and pushes gasoline from the tank, through fuel lines, and into the fuel injectors. 

Sometimes the fuel injector will get dirty, clogged or completely fail and need to be replaced.

a graphic depicting engine control unit

8 Signs Of A Failed Fuel Injector

an image showing check engine light

1) Your check engine light turns on – Obviously this light could mean a lot of things, a failed fuel injector could be one of them.

Any time an injector delivers less fuel than needed (or more in some cases), the engine’s efficiency is lowered and can trigger the check engine light to come on.

2) Rough idle or engine stalls – If your vehicle is not getting enough fuel or an uneven supply of fuel, the Revolutions Per Minute (RPM, which is the unit of rotational speed or the frequency of rotation around a fixed axis) while idling drops below the optimal level and results in a rough or even violent idle. If the RPM falls too low, the car will actually stall and you will need to restart.

3) Engine surge – If the fuel injector is spraying too much fuel into the engine cylinder, this will create a surge in the engine causing your acceleration to be much slower. When you drive, you’ll notice that the engine RPM will change noticeable under constant load rather than remaining at a constant RPM.

an image of person holding steering wheel

4) You feel or hear your engine vibrating – A failed fuel injector will cause the corresponding cylinder to not be able to fire. This means that while driving, the engine will vibrate or “hiccup” after it tries to finish each cycle without fuel.

5) Your engine misfires – If your vehicle’s engine does not get enough fuel spray due to a clogged injector, then the engine will misfire as you drive. Your vehicle will struggle to accelerate or there will be a pause after you step on the gas pedal.

6) Gas leak –  If your fuel injector is broken or cracked from damage or old age, then gas will begin to leak out of it. This is because the fuel won’t be able to reach the nozzle so it will leak from the body.

an image showing car mileage

7) Poor gas mileage – If the engine is not getting the right amount of fuel it needs for combustion, then it will place more demand on the injector to supply it with additional fuel. This results in poor gas mileage due to the excess fuel that the car’s engine control unit thinks is needed.

8) Failed Virginia State Emissions test – A broken or leaking fuel injector can cause an uneven or incomplete fuel burn and increased emissions are the result. In some cases, a fuel injector leak can cause the air & fuel mixture to be so rich that it eventually burns out the catalytic converter.

Frequently Asked Questions About A Failed Fuel Injector

Can I drive with a failed fuel injector?

We do not recommend you driving with a failed fuel injector. The issues can cause the car to stall every few moments or accelerate unpredictably, which is unsafe to you and other drivers on the road.

What is injector latency?

Latency is a measure of the amount of time it takes for an injector to fully open once it receives its signal to fire. It is usually measured in milliseconds or microseconds and is an important parameter when tuning.  Other terms synonymous with latency are dwell, offset, lag, etc.

Can I just replace one or some of my fuel injectors?

Although fuel injectors are individual, they are designed to work together with the other injectors so it’s almost always best to replace them all at the same time.