How to Clean Fuel Injectors | The Automative Guide

Back in the day, pumping fuel into your internal combustion engine may be quite a taxing job. Nowadays, in order to catch up to modern efficiency as well as laws governing fuel emissions and efficiency, the carburetor becomes the past. Now, we have the fuel injector.

Before talking about the fuel injector, let’s have a little bit of history. When modern vehicles became a trend, it had always been manufactured with the carburetor. It is a device that supplies fuel to the internal combustion engine by mixing it with air suctioned by the carburetor. However, because it involves more than just pumping fuel into the engine of the vehicle, carburetors, or carb, are quite complex to deal with. This is because it has five circuits you have to be familiar with.

The carb’s circuits are composed of: the main circuit, providing the right amount of fuel for decent driving; the idle circuit, giving enough fuel to keep the engine idling; the power enrichment circuit, needed to give that extra fuel boost going uphill or carrying heavy load; the accelerator pump, for an extra pump of fuel during acceleration; and, the choke, delivering enough fuel to heat the engine. This numerous circuits need fuel thus making this a complicated task. As we the 21st century hit, laws governing fuel efficiency proved carb to be an unlikely device for cars to maintain fuel efficiency. Although there was a time when electronic carburetors came out, the fact that it was still a complex device to work with made it even more difficult to fit the requirements of the laws imposed by the government hence came the fuel injector.

What is a fuel injector?

fuel injectorsA fuel injector, as the name suggests, is a device that directly injects liquid fuel into the combustion chamber of your engine. Now, it has actively replaced the carburetors in vehicles. Fuel injectors are now the devices used in injecting fuel into the internal combustion engine.

Are there different types of Fuel Injectors?

Yes, there are. There are three ways fuel injectors inject fuel and four types of fuel injection schemes.

Types of Fuel Injectors

Top or Rail Feed Fuel Injectors are inverted. Fuel enters from the top and is squirted at the bottom towards the engine.

Side or Galley Feed Fuel Injectors are fitted inside the fuel rail. Fuel enters from the side of the injector.

Hose Feed Fuel Injectors receive fuel from hoses.

Types of Fuel Injection Systems

injection system

Throttle Body Injectors (TBI) or Single Point Injectors was the first of the types of fuel injectors. This single point injectors were the first generation alternative to carburetors thus providing a more accurate fuel meter with less cost and more efficiency. It replaced the carb with one or two nozzles in the throttle body.

Port or Multi-Point Fuel Injection (MPFI), as the name suggests, has a separate nozzle for each cylinder in the throttle body. It is a more direct way of injecting fuel to the engine because it is right at the intake port—where it got its name—of the throttle body. Since it is direct injection, it provides more accuracy making sure that the fuel goes straight to the cylinder. This gives lesser time for the fuel to condense thus achieving a more precise air to fuel ratio.

Sequential Fuel Injection (SFI), or Sequential Port Fuel Injection (SPFI) or Timed Injection is type of multi-port injection that sprays fuel as soon as their connected intake ports open. Unlike MPFI, which sprays fuel simultaneously thus causing more fuel to hang around in engine idling, SPFI control each nozzle independently making a more accurate fuel injection when needed by each of the intake ports. It is considerably a minor alteration of the MPFI but works just as well.

Direct Injection literally sprays fuel directly onto the combustion chambers. It doesn’t have to pass through the valves in the process. Though it was a design used by diesel engines, gas engines, nowadays are also using direct injection—known as the Direct Injection Gasoline (DIG). This is an elevation of precision compared to the above mentioned injection schemes. This now allows a more even and complete fuel combustion capability for the engine. Because of this method, it lessens emissions effectively. This also allows maximum use of the fuel because it has lesser areas to go through lessening condensation and other possible leakages.

How do Fuel Injectors work?

In a nutshell, here is how fuel injectors work: Every time you step on the gas pedal, your car’s engine burns fuel for it to work. Stepping on the accelerator or the gas pedal opens the throttle valve. The throttle valve allows air to enter triggering the Engine Control Unit (ECU) to increase fuel rate as it welcomes more air into the engine. The ECU automatically prompts the fuel injectors to open fire and release fuel into the internal combustion engine. As soon at air enters and mixes with the fuel, faster combustion occurs making your car speed up.

Fuel injectors are tiny devices controlled by the ECU—which is the brain of the engine—to release a metered amount of fuel into the combustion chamber of the engine. It serves as a tiny pressurized fuel pump under your hood. It was built to open and close multiple times in a second. When the injector is triggered by the ECU to release fuel, and electromagnet pulses the valve to open. This now allows pressurized fuel to spray through the tiny nozzle.

The nozzle is devised to ‘atomize’ the fuel—meaning to turn the liquid fuel into a fine mist or vapor for it burn more quickly. As soon as the needed amount of fuel is sprayed into the combustion chamber, the ECU demands the nozzle to shut preventing further fuel to spray through. The amount of fuel needed for acceleration or even at full throttle is equivalent to an equal amount of air that mixes with the fuel to make it more combustible by the engine.

At what point should you replace your Fuel Injectors?

The engine is the heart of your vehicle, without it life won’t pump through your car. Making sure that your engine is functioning properly is the key to maintaining a properly functional vehicle. Generally speaking, a fuel injector is supposed to last the entire lifespan of your vehicle but there will always be variables that may affect your fuel injector. Here are key indicators of a problematic fuel injector:

Your Engine Misfires

fuel injectors problemsThis is a common and fixable problem. Instances occur when SPFIs missed a dose of fuel into one of the cylinders causing one of the cylinders to misfire. When sequential doses of fuel is engaged it may happen that not enough fuel pumped into the injector would be able to release enough fuel for a cylinder making the car run less smoothly and in the long run will cause promising damage to your engine. This is when MPFIs come in handier than SPFIs because they spurt fuel simultaneously compensating for the missed dose of fuel.

Pre-ignition or Detonation

fuel injector detonationPre-ignition or detonation happens when your injector is dirty or worn-out. Detonation—not in a dangerously bomb explosive definition—is when faulty fuel injectors cause remaining gas at the end of its burning cycle sparks and simultaneously combusts. In a general sense, it comes harmless to the driver and the passengers but has major potential damage on your engine and some of your car’s main components. Detonation also causes pitting and scuffing around your pistons.

Pre-ignition happens when the air and fuel combusts before the spark plugs ignite. This then causes extraordinary high engine temperature and damages your pistons. This may be caused by other problems in your engine but mainly it is a clear indication of a faulty fuel injector.

Your Engine Shuts off

car engine shut offWhen your engine shuts off because it’s flooded by fuel, it’s a big problem. It’s like the heart that stopped pumping and too much blood is pouring into the heart. This is caused by leaking injectors. It suffocates the engine. The danger doesn’t just end there. When you get to fix the flood and the leak, you have to make sure that your engine is cleaned up because if you don’t, the fuel that evaporated and settled on the engine will cause a more extensive damage when you start the ignition.

How to clean Fuel Injectors?

There are three common problems to deal with in fuel injectors: dirty fuel injectors, clogged fuel injectors, leaking fuel injectors caused either by a faulty valve or a crack. The dirt that either makes the fuel injector dirty or clogged can be from contaminated gas or diesel. Dirty fuel and even air pollution can clog the valves causing a faulty fuel injector.

Planning on going to a mechanic to do the job for you? No need! You can clean your fuel injectors yourself! There are two ways of doing it.

  • Manual Cleaning

Manual cleaning fuel injectorThis is the cheapest and most effective yet dirtiest and most time consuming way of cleaning your fuel injectors. However, this is only recommended by people who have extensive knowledge in disassembling your car engines. Disassembling your engine isn’t something a novice can do. It needs special care and extreme caution in dealing with parts removal from your car.

The problem with manually cleaning your fuel injectors come AFTER the cleaning. You have to conduct tests—which professionals are required to do—in order to check if the cleaning was done properly and that there are no other elements that entered the injector causing further problems. You have the need to conduct CO and HC emission tests as well as injector pressure drop test.

After these, doing another round of cleaning cycle is also required to fully clean and de-clog your injectors properly. And one of the things you need to make sure of is the proper use and mount of solvent needed to do the job. Choosing the right solvent will also cause a problem to other parts of your engine.

  • Cleaning with a Fuel Injector Cleaning kit

Fuel Injector Cleaning kitThis is the best way of cleaning your fuel injector yourself.  Make sure you stick to the instructions exactly to lessen possible problems in the future.

  1. Take the fuel pump (it must be turned off) and connect it to the fuel return line to the gas tank.
  2. Disconnect the pressure regulator and hook up the cleaning kit to the fuel port.
  3. Remove the gas tank’s fuel cap to prevent pressure from building up.
  4. Turn the ignition to avoid the engine from turning over.
  5. Open the valve on the kit until it matches the pressure reading for your vehicle—normally it comes written in the car’s service manual. If in case you lost the manual, it may also be written in the kit’s instruction manual.
  6. Turn on the engine and let it run for about five minutes or until the solvent is used up. Sometimes, the engine will shut off on its own. This allows the cleaner or solvent to pass through the injectors.
  7. Remove the fuel return line and rest the fuel pump switch. Cover the gas tank.
  8. Reattach the pressure regulator.
  9. Turn on the ignition to check if the fuel injector is already cleaned up or working properly.
  10. You should pay attention to possible noises that may indicate something else is wrong but overall a good smooth clean rev verifies a good fuel injector cleaning.


Fuel injectors are comparably the same to the valves in the heart. They are responsible for controlling the amount of fuel that enters the internal combustion engine. They are vital to the efficient use of fuel inside your engine. With these, car owners are able to pocket in more bills due to fuel savings and go further with better mileage due to the way fuel injector regulate the maximum use of fuel in the engine. Thank you for your reading. Browser our website and find out more information about car.

How to Clean Fuel Injectors | The Automative Guide
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1 thought on “How to Clean Fuel Injectors | The Automative Guide

  1. I didn’t know that there were different types of fuel injectors! My friend took a look at my car and told me that it needs new fuel injectors and I had no idea what to buy. I’ll have to do some research to find the right kind of injector for my car! Thanks for the information!

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