Can a Bad Fuel Injector Damage My Engine?

If you pop the hood of a car from the ’60s, ’70s, or ’80s, you’ll likely see a carburetor sitting on top of the engine. Before the rise of electronic fuel injection (EFI), carburetors were the standard system used for delivering air and fuel to the combustion chambers in an engine.

Fuel Rail Assembly Removed From Car

As technology changed and advanced, fuel injection systems have taken over. EFI systems consist of a fuel pump, fuel rails, oxygen sensors, and fuel injectors. EFI also utilizes a computer to control the amount of fuel being injected into each cylinder. Electronic fuel injection offers better fuel economy, consistent power at verifying elevations, and generally less maintenance. While there are many components that make an EFI system work, in this article we are going to focus on the fuel injector, and the potential problems that can arise if one fails.

What is a Fuel Injector?

The fuel injector is a component that controls the amount fuel being delivered prior to combustion. These small parts connect to the fuel rail and the either the engine block (or the intake manifold on some port injected vehicles), and plug into a harness that communicates with the ECU

Volkswagen Fuel Injector

What Causes Fuel Injector Failure?

While EFI systems are generally pretty reliable, fuel injectors can run into some problems. The spray nozzle on the end of the injector can become clogged with carbon deposits, preventing it from closing entirely. The plastic electrical connection points are exposed to extreme temperatures and can become brittle, causing issues with connectivity. Lastly, rubber seals in the injector can dry out and crack, causing external leaks.

Symptoms of Fuel Injector Problems

Failed or failing fuel injectors can cause a variety of issues.

  1. Misfires
  2. Rough Running
  3. Sluggish Acceleration
  4. Reduced Fuel Economy
  5. Check Engine Light
  6. Fuel Oder

And more.

Can Faulty Injectors Cause Engine Damage?

Most of the time, the symptoms of a failed injector will be significant enough that you will get it fixed quickly. In all likelihood, you will not run into this sort of damage because you won’t be driving with a faulty injector for long. That being said, there are some serious (and expensive) consequences that can happen if you neglect to replace a bad injector.

Hydro Locking

If the injector fails in a way that causes it to dump fuel constantly into the cylinder, the engine can hydro lock. Hydro locking occurs when the path in the combustion chamber that normally compresses vapor and gasses is filled with liquid. The liquid is unable to compress to the same degree and can result in a bent connecting rod, piston damage, or worse.

Bent Connecting Rod Resulting From Hydro Locking
This connecting rod bent as a result of hydro locking from a failed injector dumping excess fuel into the cylinder.

If severe engine damage happens as a result of hydro locking, your motor will need to be rebuilt or replaced.

Bearing Damage

Oil’s lubrication capabilities are reduced when fuel is mixed in with it. Without proper lubrication, damage to the bearings can occur. If this happens, the engine will need to be opened up and bearings will need to be replaced.

Catalytic Converter Damage 

A faulty injector that consistently dumps excess fuel can damage the catalytic converters. When unburned fuel enters the catalyst, it can combust. The extreme heat given off by combustion can wreak havoc on the inside of the expensive catalyst. Replacing failed catalytic converters is extremely expensive.

Flooded Engine

If you have a failed fuel injector dumping excess fuel into your engine, it can end up flooded. In a similar situation to hydro locking, your engine can flood when you go to start it up and the injector fills the cylinder with unburned fuel. As a result, your car will not start.

Don’t Put Off Fuel Injector Issues

If you’ve noticed symptoms of injector failure while driving, don’t delay! While the risk of severe engine damage is relatively low, it’s not impossible. More importantly, replacing a bad fuel injector will improve the fuel economy, engine power, and overall drivability of your vehicle.

Fuel Injector Replacement at Scott’s U-Save

At Scott’s U-Save, we want to keep your vehicle running at its best and prevent catastrophic damage whenever possible. We have teams of ASE-certified technicians at our locations in New Lenox and Steger Illinois, as well as Schererville Indiana. Give us a call or schedule an appointment online today!


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