Here's the complete guide on Fuel injector problems, repair, and mainteance!


Posted by: Henry Egan

Share this post:

Latest news articles

Did you know that a leaking Fuel Injector might cause car fire or even more detrimental causes? Read on to learn all about its problems, repair, and maintenance tips!


Fuel injectors play a very pivotal role in the internal combustion engine, as they help in regulating vehicle speed and acceleration by constantly varying air/fuel ratio entering the engine. The device is responsible for taking fuel in its natural liquid form and then supplying an atomized form of this liquid to the intake manifold of a vehicle's engine for its onward injection to the engine's combustion chamber.

To achieve this function, the fuel injectors are mechanically connected to the car's throttle, such that when you step down more on the throttle, more fuel is allowed into the engine through the injector, and thus, the higher vehicle speed is achieved.

However, leaking fuel Injectors is one of the most common fuel injector issues reported by vehicle owners and mechanics. So, in a situation where one of the fuel injector parts malfunctions, like the O-Ring, then there is always a chance of fuel leaking from the body of the injector and that is a perfect recipe for a car fire. To find out more about how leaking injectors can result in a car fire please go down to the leaking fuel Injector problems, repair, and maintenance section below.


Fuel Injectors have completely replaced the carburetor

But first, we'll like you to gain a solid idea on the working of fuel injectors, it's better to get acquainted with the different types of fuel injector and fuel injector functions:

Fuel injector types:

  • Throttle body fuel injector
  • Multi-port fuel injector
  • Sequential fuel injector and
  • Direct fuel injector

Please check out the following article on What is the Fuel injector? Why is it important? for a detailed explanation of the different types of fuel injectors and the fuel injector working principle.

Fuel Injector problems, repair, and maintenance

1. Fuel Injector problems

Leaking injector, a Good Recipe for a car fire

Fuel injector leakage can be either external or internal, with both capable of causing a fire. As you must have seen in the What is the Fuel injector? Why is it important? the article, one of the conditions for the proper working of the injectors is for fuel to be supplied to them at considerably high pressure by the fuel injector pump.

This condition usually poses its mechanical failure concerns on the injectors, as most of them tend to fail by cracking on the sides due to the high fuel injector pressure (especially obvious in substandard injectors). This kind of failure results in external leakage as fuel can be seen leaking away from the body of the injector and down the side of a usually hot engine block, a good recipe for a car fire.

On the other hand, fuel injector failure also tends to result from faulty or damaged fuel injector seal ( the O-Rings). O-Ring induced leakage is generally noticed in the Multi-port fuel injector system and sequential fuel injector system that make use of fuel rails to supply gasoline to the different injector ports simultaneously.

Damaged O-Rings allow fuel to leak past them on the side into the engines intake manifold rather than through the fuel injector nozzle. This results in the wet flow of petrol within the intake manifold rather than an atomized form of fuel that is usually required within this manifold. As a result, liquid fuel might find its way into the combustion chamber and then go past it to the oil sump below.

When the sump gets filled, the seals may begin to fail and the mix of fuel and oil will leak onto the body of a usually hot sump. Another very good recipe for a fire.


Leaking fuel injectors are a great recipe for a car fire

Dirty or clogged injector or lines

This is one of the biggest issues noticed with fuel injectors. The nozzle can become dirty over time so without adequate maintenance, this nozzle becomes blocked partially due to the dirt it has accumulated. When the engine is shut off the heat is soaked up by the injector which causes leftover fuel in the injector to evaporate leaving some deposit behind which would block the system in the long run.

Check out the following video on cleaning your fuel injector:

Cleaning Dirty or Clogged Fuel Injectors - DIY Without Using Expensive Equipment

2. Fuel injector repair

Before we dive into fuel injector repairs, let me give you the possible fuel injector leak symptoms and of course how to diagnose these fuel injector symptoms respectively.

Symptoms of fuel injector malfunction

  • Increased fuel consumption
  • Hard start when the engine is hot
  • Emission test failure (You can check out the Simple technique of testing fuel injectors)
  • Oil thinning which can lead to serious engine failure
  • Engine knock or detonation
  • Engine pollution
  • The engine does not reach full rpm
  • Smoke from tailpipe
  • Surging and buckling under various throttle loads and generally poor performance

How to diagnose or detect fuel injector problems

  • If you observe any of these signs or symptoms use a code reader. The electronic control unit (ECU) will pop up logged errors, if the engine misfires because of one bad injector, the error code will point to the injector in question.
  • Another way is to use an engine stethoscope. To diagnose this problem place the tip of the stethoscope on each injector and listen to the sound it makes normally a working injector will make a sharp clicking sound, therefore, the absence of this sound signifies a problem with that particular injector, so remove check and repair or replace the injector.

Now to fix a fuel injector one will either replace completely bad parts or change the whole injector or just clean clogged parts. See below for some repair tips.

  1. Replace faulty O-ring
  2. Replace the old one with new injector if the nozzles or any internal components is cracked
  3. Injector seals and washers are cheap and can easily be replaced by loosening with a wrench
  4. Dirty injectors: Have them inspected and cleaned out at regular intervals using fuel injector cleaner and fuel Injector Lubricant. You can learn  How to clean fuel injector DIY by clicking on the link
  5. Clogged injectors: They can be repaired if the problem is noticed in time but a total overhaul will be required if it is too late.

Fuel injector flow testing

The cost of fuel injector flow testing falls within ₦2000 to ₦5000 or less per injector depending on the make of the vehicle. Flow testing can be carried out under the following subheadings.

  • Leak inspection this could be internal or external
  • OHM testing: this is to verify the condition of the injector coil, which is tested for resistance across the terminals of the injector coil
  • Spray Pattern Verification: Spray patterns are evaluated to investigate for deposits of dirt on the nozzle which affects the spray pattern. This can be corrected fuel injector cleaning
  • Pulse operation: pulses can be observed when the vehicle is started from idle to full throttle any discrepancies can be detected and resolved
  • Flow rate verification using a fuel injector flow calculator: These checks for internal deposit or condition that affects the rate of flow, cleaning the injector can correct this problem
  • Seal replacement: Damaged seals are replaced when problems are detected

 Cost of repair

 The cost of repair of fuel injectors can go from ₦5000 to ₦30,000 and an overall average of ₦50,000. This also depends on the make of the vehicle.

3. Fuel injector maintenance

With adequate maintenance, fuel injectors can last as long as the engine itself the following are some of the ways or methods of maintaining a fuel injector. For at least every 40000 km or 25000 miles once you have the fuel injector checked and cleaned or if you use your car more frequently then a lesser mileage

  • Use of fuel additives: Add fuel injector cleaner to the fuel tank, some fuel additives manufacturer claimed that it gives the vehicle extra power and increases fuel efficiency.


A properly working fuel injector improves overall fuel efficiency

  • Regular engine service: Change the oil and air filter regularly because overused engine parts put extra loads on the vehicle's fuel injection system.
  • Driving habits: cars used for shuttles and driven too hard at the same time will give the injection system problems since the engine does not have enough time to cool before embarking on another journey. One should make sure that he gives his car engine enough cooling time.

Cost of maintenance

Maintenance cost is quite affordable costing between ₦5000 to ₦20,000, this could be more depending on the vehicles make. All you need do is have handy the fuel injector kit,  fuel injector oil, and fuel injector filter.


Running a fuel system cleaner through the vehicle couple of times a year is a great idea as this will help keep the injector, fuel pump, and fuel lines clean and clear of carbon build-ups it will also increase the service intervals of injectors. The fuel injectors do not last forever but one can make it seem so with regular maintenance. With injector systems, better gas mileage has been observed compared to older technologies like the carburetor with its different carburetion styles.

We hope you learned something new and important on fuel Injector problems, repair, and maintenance section below. Look out for this article that highlights 7 obvious symptoms to know a damaged fuel injector.

>>> Arm yourself with the best Tips & Advice, and market info on

>>> All topics to check out: Latest car newsCar Prices, and Reviews.

Henry Egan

Henry Egan


Henry Egan a poet, essayist, content writer, blogger and technical writer who is willing to read just that last material to develop the best content possible. Henry feels he is more of a new generation writer with a sassy and swanky style. You can be sure you'll get all the facts in and never get bored with his articles.

He has got a flair for technical reviews on automobile and cars. He studied Mechanical Engineering but his first love remains Literary Art.

See more