How to clean a fuel injector

A fuel injector, in simple terms, is typically built using both solenoid components, and a fuel injector assembly. Fuel starts by going through a fuel filter, passing solenoids and through the valve spring. From here, fuel passes into the spray tip and fires atomised fuel into either the inlet or manifold, or in some cases the cylinder head, in which are angled so that the spray of fuel is fired towards the inlet vale. There are two different types of injectors, dependent upon the vehicle and injection system type.

In essence, fuel injectors are small electro-mechanical devices that are responsible for spraying fuel into the intake valve to power your vehicle. Since the fuel acts a natural lubricant for the injector, it’s understandable why and what types of critical damage water (or condensation) can do to your fuel filter and injectors – removing the necessary (fuel) lubricant to the inside of this vehicle part and in turn damage, rust, or even destroy your injectors and engine overtime. Also, since an injector is made out of a screen, magnets such as the magnet coils, and steel or metal injector needs and ports the amount of damage, rust, wear, and tear condensation and water could cause become a little more obvious to vehicle owners.

Since injectors are responsible for opening and closing at the same rate of RPM”s as the engine, one could appreciate how critically important proper functionality of this part is to the powering and maintenance of your vehicles performance.

Cleaning Your Fuel Injector: How it’s done

From engine and acceleration hesitation, shaking, poor gas-economy all the way to unusual or poorly inconsistent idling, there are plenty of various signs and reasons for wanting to change your fuel injectors. However, it is recommended to simply just do it at it’s regularly scheduled maintenance period, as opposed to waiting to experience these types of common problems, false sensors, or other lapses in vehicle performance.

Vehicle owners may elect to clean their vehicles fuel injector on their own, and it doesn’t take too much expertise or tools to get the job done. In fact, it’s as simple as purchasing a fuel-injector cleaning kit and a fuel-line disconnect tool.

Before getting started – Keep in mind that while most fuel injector kits are universally designed for any type of vehicle, that it’s important to read the back instructions before purchasing, and again before using just to be sure, as they can differ. Also, the necessary cleaning fluid is also typically sold separate from the tools and canister, so ensure you purchase the right brand and model canister and tools specifically designed for your vehicle and model.

Also, before diving in, ensure you understand your engines layout, where your fuel injectors are located, and also identify the fuel pump and all of its parts and positively understand them before taking anything apart or changing parts.

Step 1Before taking the first step which is disconnecting the fuel pump from its injectors, it’s important you connect the fuel return line, or opt to using a U tube (purchased separately) so that while you’re changing the fuel injectors the gas stays in and returns back to the tank as necessary. Keep in mind that dependent on your vehicle type and model that you might have to also temporarily remove the fuel pump relay and/or fuse. Bare in mind, that through this process disabling the fuel pump or return line may set off a faulty-code, which will have to be adjusted or set later on.

Included instructions should help understand how to disconnect the fuel pump, and also how to use and insert a U tube, or connect your fuel return line as necessary.

Step 2 – Disconnect your pressure regular vacuum line to avoid both confusion and unnecessary leaking or any dangers to you while performing the injector and filter change, cleaning, or repair.

During this step, if you’re comfortable, attempt to remove any fuel varnish or build-up in the throttle body or intake tract using an appropriate, vehicle approved aerosol cleaning spray. Also take into consideration stopping and cleaning your combustion changes and intake valves also using a similar “top cleaner” product from the auto-parts store. If you have an engine that is burning oil this can be especially helpful, and while you have your engine and hood propped up it wouldn’t have to replace the spark plugs as well as changing your oil and filter in the process – this will optimize your vehicles total performance post-injector cleaning.


Step 3 – The next step requires connecting your cleaning kit via the test port to your fuel pressure. This is located, via the instructions you should be referring to, and found in your engine, attached to your vehicles ‘fuel rail’ (see instructions; blueprint).

For understanding how to fit and attach the hose to your fuel port refer to instructions, be careful, and take your time. If unsure, contact your manufacturer, or consider looking at online images that match your vehicle, model, and engine layout – specifically the fuel port.

Keep in mind through this step that the cleaner is in in fact flammable, so it’s critical that you ensure your vehicles fuel injectors have no exposure to fuel during this process.

Step 4– Since unwanted and extreme pressure can build up in your fuel system, causing combustion (an explosion or fire), it’s very important that you open up your fuel cap at or before this step. As the warnings should indicate in your instructions cleaning kits in general have a tendency to create one big burst of pressure at once, making it nearly impossible to reverse any damage done by making such a dangerous mistake.

Step 5 – The next step involves turning your vehicle on and testing your ignition that when the fuel pump shuts off that your engine will not turn over. Keeping your fuel pump off is very important.


Keep in mind it can take 10 minutes or more for all of the cleaner to cycle through and clean your injectors and become acclimated both the liquids and familiarization of exposing your injectors to a foreign object or fluid. As you complete this step, in theory, your engine should turn off on it’s own after the cleaner has been fully used up if done correctly.

Step 6 – As you come up to your final steps, reset the fuel pump (critical) and replace your gas cap to secure both fuel and pressure. It’s important that the fuel pump and pressure regular vacuum house are also reconnected, otherwise harm could be done to your fuel filter injector system or engine. Is your pressure regulator reconnected? Good.

Step 7 – The final step in the process of cleaning out your fuel injectors consist of turning your vehicle back on again to ensure everything is running – and sounds – smooth. It’s recommended to take your car for a short ride, that it’s not accelerating rough, having any seemingly RPM-related problems, and that the engine is performing well, quietly, and as it usually does – or better!

Final pieces of advice

Assuming you followed the directions step by step, if for any reason you are experiencing unusual performance or sounds, it’s recommended to have your vehicle looked at by a professional, licensed mechanic. A rapid clicking sound in a balanced sequence coming from your injector represents optimal and proper functionality. You can test its operation by using a long screwdriver to feel and measure the clicks, frequency, and any unusual patterns.

If after cleaning your fuel injectors your vehicle still is experiencing unusual or poor idling, RPM response, acceleration, or other unusual performance issues it may very well be necessary to replace your fuel injectors, or consider a tune-up if you haven’t had one in a while – check your


Keep in mind that if it’s been a while since you changed or cleaned your injectors that the necessary amount of cleaning chemicals may not be able to cycle through to clean your fuel injectors as-needed.

If interested, you can do pressure, CO, and HC level checks via your emissions or utilizing the injector-pressure-drop test to determine if at all, how effective your fuel injector cleaning efforts have been.

While it can be both cheaper and convenient to clean your fuel injectors on your own, if in doubt or uncertain of your level of comfort with your vehicle it may be best to leave this up to your trusted and licensed local mechanic. Considering the different types of combustible mistakes or damages to the engine that could be done, this might be most practical. If in doubt of any of these steps or you do not feel you understand, refer to either the instructional manual or consider bringing along a trusted friend to supervise and assist you as needed. It’s always helpful to have a second pair of hands or eyes, and there’s nothing wrong with sharing the work with a loved one or friend, especially if they use your vehicle too.

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