How to Tell if Fuel Injector is Bad – 3 Important Signs

Increased fuel consumption, poor engine Performance are all signs to tell if fuel injector is bad or not. Fuel injectors are located in the intake manifold and spray fuel through a tiny nozzle.

The sold function of the injector is deliver fuel to the combustion chamber via a special nuzzle as fuel mist. The injector uses a delivers fuel to the combustion chamber as mixed fuel mist instead of a strong jet stream in the case of a carburetor.

How to Tell if Fuel Injector is Bad or Dirty

Dirty fuel injectors are the most common cause of poor ignition quality. Dirty fuel injectors can lead to some serious issues like hard starts, low combustion efficiency, and loss of power.

It is important to know how to tell if your fuel injectors are bad or just dirty. The best way to do this is by testing the fuel pressure on startup. If you have a digital gauge, then it is easy to test the pressure by using this method:

  • Start the engine and turn it off after 5-10 seconds
  • Gently push on the throttle until it reaches its idle speed
  • Wait for about 15-20 seconds and then disconnect the air hose from your gauge or let go of throttle gradually

When the throttle valve opens, your fuel injector sprays fuel to mix with the air and then enters the engine’s combustion cylinders. If for any reason, the injector stops to perform its functions normally then it will affect the engine performance.

Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. Now the big question is how if fuel is injector is bad or not and how to fix a clogged fuel injector.

Common Signs to Tell if Fuel Injector is Bad

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If a fuel injector is bad, it means that the injector has failed or is failing to preform its normal function. A number things can cause an injector to malfunction or even stop working totally.

One of the things that could make a fuel injector to be bad is dirt, another thing is tiny carbon in the fuel. Without intentionally introducing dirty the injector it self an get clogged from residues in the fuel.

Below are the most common and evident sings and symptoms of a clogged or bad injector

  1. Difficulty is starting the engine.
  2. Poor idle.
  3. Failed emissions.
  4. Poor engine Performance.
  5. Engine does not reach full RPM.
  6. Strange increased in fuel consumption.
  7. Rough engine performance.
  8. Surging and bucking under various throttle loads.

This signs and symptoms remains the same with all injectors regardless of car brand or manufacturer. If you notice any of the above mentioned symptoms in your car when you should consider replacing the injectors or cleaning them.

There some remedies that are said in the case of injector dirt and clog. An injector cleaner is a very good product and step forward to keep the injector in a good working condition.

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How to Maintaining and keep Injectors Clean

Maintenance is what determine how much a car in general lasts. whether or not your are driving a new car if your don’t maintain it, the car will get spoilt early than it should.

The same principle or maintaining your car applies to the fuel injector lifespan as well. The fuel injector needs to be kept clean at all times regardless of being new or old.

Like i said before one the ways to keep the injector clean is by using the injector cleaner. Apart from the use of injector cleaner, there are three ways to keep your EFI system flowing and your engine running which includes:

  1. Use TOP TIER detergent fuels (this is not the same as octane level). Only certain brands are classified as TOP TIER, whose fuel contains detergents to keep EFI systems running clean with every fill-up.
  2. If not using TOP TIER fuels, in-tank fuel injector cleaner every 5,000 miles will make up for the detergents not added in the fuel.
  3. Drive regularly. There’s nothing a vehicle can’t endure more than not being driven. As stagnant fuel ages, it can separate and evaporate, leading to the formation of deposits in the EFI system. If you must park your vehicle for a time, add fuel stabilizer to the last tank of the season and run the engine at least 15 minutes to get stabilized fuel to the injectors.

Can fuel injector cleaner cause problems?

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There a lot of injector cleaner products in the market but the only tested and trusted injector cleaner that will not damage your car is Techron from Chevron. Even with the use of fuel injector cleaners, with time the injector get old dirty and sometimes fail totally.

One may also ask, how often should I put fuel injector cleaner in my car? The times to use the fuel injector cleaner depends on the type of transmission you have:

  • Gas-injector cleaners should be used every 1,550 miles.
  • Diesel-injector cleaners should be used in every tank.

If you find your self in this condition where the fuel inject has totally failed or has been blocked by dirt, replacement might be the best option. You could also try removing the injectors and try a bench injector cleaning.

What Happens When a Fuel Injector Fails?

The fuel injector is a part of the engine that makes sure that the right amount of gasoline is being injected into the engine. If a fuel injector fails, there are some symptoms that may present themselves.

One of them is an engine hard start, another one is poor acceleration, If you have noticed either one of these symptoms, it’s important to have your vehicle checked by a mechanic as soon as possible.

Fuel injectors are not an easy part to replace so if you notice any symptoms related to this part, it’s best to have your vehicle looked at by a mechanic as soon as possible.


Fuel injectors are a vital part of most fuel-injected engines. They allow fuel to be sprayed into the engine at a high pressure, which allows the engine to run more efficiently and also reduces emissions.

It is recommended that you have your injectors inspected by a professional if your car is over five years old, or if you have been having any issues with starting or idling. These can be signs that your fuel injectors need to be replaced.

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