A fuel nozzle is a pressurized liquid or powder distribution mechanism. It is responsible for supplying the combustible mixture and its subsequent efficient combustion.


Sometimes the operation of this mechanism is disrupted due to clogging. How to know if fuel injectors are clogged, what are the symptoms of clogged fuel injectors and how to fix the problem in time, we will reveal in this article.

What causes clogged fuel injectors 

What do fuel injectors get clogged? Let’s figure it out!

The most common problems of clogged fuel injector of any type include the deposit emergence on the walls of parts, which are the result of using low-quality petrol or diesel. The basis of these deposits are chemical compounds and particles (for example, sulfur) found in automobile combustibles.

As a consequence the contamination in the flammable liquid supply system and the occurrence of interruptions in operation, loss of engine power, excessive consumption of gasoline and lubricants.


Another reason for a fouled atomizer is fake filters, or untimely replaced filters.

Symptoms and signs of a clogged fuel injector

Everything has its signs and now you will learn how to know that the fuel injectors are clogged. Here are some common symptoms of it:

  • engine vibrations and rough idling,

  • engine misfire,

  • bad diesel or gasoline consumption,

  • combustible leaks and smell,

  • exhaust system toxicity.


Let’s talk about each of them!

Engine vibrations and rough idling

Can clogged fuel injectors cause vibration?


Or can clogged fuel injectors cause a car to stall?


Let’s analyze! Sometimes small vibrations of the engine are normal, but the vibrations in this case are sharp and strong. A faulty nozzle will cause the affected cylinder to fail to ignite.This will cause the engine to vibrate while driving due to lack of petrol or diesel. In most cases, this is accompanied by an engine stop or rough idling. A stalled engine usually occurs if the RPM drops too low or suddenly.

Engine misfire

The motor will misfire while driving if insufficient petrol or diesel is sprayed into the engine due to a fouled nozzle. A car might sputter, stumble, or lose RPMs. After stepping on the gas the vehicle won’t pick up speed and you will feel the vibration. The nozzles should be diagnosed and then cleaned or replaced. 

Bad diesel and gasoline consumption

The nozzles are under a heavy load due to insufficient gasoline for combustion. This overloads them greatly. In fact, there is enough gasoline, but the engine control unit thinks that this is not the case. The reason is a fouled combustible nozzle.

Combustible leaks and smell

A clogged fuel injector can also cause gasoline or diesel to leak. For this reason, the engine will again not have enough fuel. It will simply drip from the nozzle body. To determine this, you can inspect the fuel nozzle or smell unburnt combustible in the vehicle.

Sometimes combustible lines or a faulty sensor telling the ECU to inject more fuel, can be the cause of the smell.

Either way, you need to find what's causing the bad gas smell and fix it right away before your safety is at stake.




Exhaust system toxicity

A broken nozzle causes incomplete combustion of petrol. Because of this, the catalytic converter burns out and emissions increase.

What happens if your fuel injectors are clogged?

With a small fouling, there are no special problems with the engine. Usually, there is an increase in gasoline consumption by 1-3 liters per 100 km. When using bad gasoline, detonation may occur.


At the average stage of fouling: the difference in the productivity of the nozzles is about 10-15%. At idle, the engine begins to run unevenly. The exhaust comes with chaotic blows. Gasoline consumption increases noticeably and acceleration dynamics worsen. Detonation and a pungent unpleasant smell from the exhaust pipe appear. 


The difference in injector productivity reaches 20-50% at the critical stage of fouling. The engine vibrates a lot. One or more cylinders may not idle at all. When you try to sharply press the gas pedal, sounds can be heard in the air filter housing. Symptoms of the first two stages are also present in a more apparent form.

How to check if fuel injectors are really clogged?

It is not easy to diagnose this problem, because the symptoms of clogged fuel injectors are similar to many others. Engines consist of complicated mechanisms and there are usually several parts in the system that can produce similar symptoms when failing. 


If a vehicle sat for an extended period with petrol in the tank, it can be supposed that the combustible system is gummed up with bad gasoline or diesel, varnish and sediment. In this case it is better to clean the whole combustible system.


You can find a broken combustible atomizer by disconnecting the connectors one by one. If the motor speed decreases, then the nozzle works well, if it doesn’t, then the atomizer is broken.


There is a certain algorithm for determining whether the injectors are fouled, but it is quite complicated for a non-professional person. It is better to contact a service station when you suspect something wrong with an atomizer and see some symptoms pointing out the problem.This process can take hours.

How to clean clogged fuel injectors

How to clean clogged fuel injectors

Car owners often wonder how to fix clogged fuel injectors, can clogged fuel injectors be cleaned?

In the case that the inspection revealed that the main cause of the failure is the atomizers, they must be replaced or cleaned.


There are 2 main ways to clean the nozzles:

 • flushing the nozzle with washing liquid,

 • cleaning the atomizers with additional ultrasonic.


Special petrol or diesel additives can be used to increase the octane number. For optimal cleaning of the entire combustible system, we recommend using BIZOL GDI POWER CLEAN. It can be filled directly into the diesel or gasoline tank at every maintenance or every 10,000 km. This additive reduces deposit formation and increases nozzle life regardless of what causes clogged fuel injectors.

For optimal cleaning of the entire fuel system, we also recommend using BIZOL Gasoline System Clean+ g80.uct-range. 


Contamination of the atomizers is inevitable, but regular cleaning of the parts will allow you to maintain the best performance of the car.


During ultrasonic washing, the nozzles are removed from the engine and placed in an ultrasonic bath, where they are washed using the cavitation effect.


If you have no particular problems with the car, the engine idles smoothly, then of course it is better to do liquid cleaning of the nozzle. The procedure is useful not only for the atomizers themselves, but also for the engine (removes soot from the valves and combustion chamber). With the first and second stage of clogging of the nozzles, liquid cleaning will easily cope!


In situations where the nozzles cannot be cleaned, they are partially or completely replaced.


So, now when you are driving your vehicle remember to keep an eye out for symptoms that might indicate dirty, leaking or fouled nozzles. Or avoid them by using cleaners and additives regularly.

How to clean clogged fuel injectors
GDI Power Clean 0.5L

  • Effectively removes deposits on the surface of the injector needle tip and throughout the combustion chamber   

  • restores the original performance of the engine  

  • ensures regular engine running and reduces fuel consumption  

  • reduces maintenance costs  

  • ensures environmentally friendly, low-pollution combustion  

  • reduces the risk of engine damage due to LSPI (Low Speed Pre-Ignition).

Gasoline System Clean+ g80 250ml

  • cleans injectors efficiently  

  • removes carbon deposits from intake valves and combustion chamber 

  • increases the performance of engine

  • reduces fuel consumption and lowers emissions  

  • extends the life of the fuel system

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