How to Test and Clean Fuel Injectors

mechanic fixing fuel injector

We all want the best mileage and performance from our vehicles, and one of the keys to an optimally functioning engine is a clean fuel injector. However, additives and hydrocarbons present in fuel can often leave gunk or buildup around the nozzle of the injector, causing poor fuel flow, ineffective atomization, and uneven distribution.

Ideally, you should be fueling your vehicle with a high-quality fuel that limits the amount of buildup in your injectors. However, even the most well-fueled injectors must be cleaned or replaced at some point.

Unlike many engine parts which require regular maintenance, there is no specific time or mileage that indicates when you need to clean your injectors. Fortunately, when your fuel injector is dirty, your vehicle has many ways to let you know that it is time to clean them.

Symptoms of a Dirty Fuel Injector

One of the first things you will notice is a significant reduction in power or acceleration. Reduced power is often due to an ineffective ratio of air to fuel, which can result from a clogged nozzle.

You may also notice a decrease in fuel efficiency as your engine uses more fuel to maintain the same level of performance. Stuttering and misfires can also indicate blocked injectors due to missed strokes.

These symptoms may not always result from dirty injectors. Other engine parts failing can also cause these problems. So, if you want to be certain that it is the injectors that need cleaning, you will need to perform a diagnostic test.

How to Test Your Injectors

Cleaning injectors can be a complex and laborious task, and, if you aren’t mechanically minded, you may damage important engine parts. Save yourself some time and trouble by performing a couple of simple tests before diving in.

To perform these tests, you will need a fuel pressure gauge, an injector tester, and a test light.

Check the Fuel Pump

  1. Locate your fuel pressure port along your fuel rail. Remove the plastic cap and attach the fuel pressure gauge with the correct adapter.
  2. Consult your car’s user manual to check the fuel pressure for your car’s make and model. This is usually between 50 and 60 Psi for most cars.
  3. Turn the key in the ignition to the ON position to prime the fuel pump.
  4. Observe the gauge reading to find the pressure of the fuel pump. Make sure to wait a couple of minutes for the pressure to stabilize before checking the final reading, as the pressure can oscillate.

Check if the Injectors Are Receiving Power

  1. Unfasten the connector for your fuel injector. The method for doing this will depend on your harness.
  2. Connect the test light to the negative terminal of the battery and apply the point of the test light to each of the two injector wires. The test light will light up with each one, indicating there is sufficient power going to the injector and, therefore, it is not faulty or damaged.
  3. Repeat this with each injector.

mechanic troubleshooting car engine

Check the Trigger Circuit

  1. Connect the test light to the positive terminal.
  2. Start the engine and leave it running.
  3. Test the opposite wire.
  4. Check for flashing or flickering, which indicates that the signal is being correctly transmitted to the ECM.
  5. Disconnect the wiring clips from the injectors and perform the test again; reconnect the wire with the test light attached to check that the flickering remains consistent.

If the injectors’ component and power supply are all functioning, the injectors are probably blocked and need cleaning.

How to Clean Fuel Injectors

If tests indicate the injectors are dirty, there are two methods to clean them. However, the easiest, most user-friendly, and often most successful method is to use a cleaning kit.

You will need an injector cleaning kit, air compressor, and fuel pump regulator.


Ensure the kit is compatible with your vehicle and the cleaning solvent is the correct one for the kit. Fill the kit canister with the solvent, and then connect the kit to the fuel port located on the fuel rail.

Disable the fuel pump, and either connect the return tube or a U-tube so that the fuel returns to the tank, and connect the fuel pressure regulator. Then check the fuel pump is inactive by turning over the ignition and opening the fuel cap to prevent pressure buildup.

Connect the compressed air hose and adjust the pressure according to the kit manual guidelines.

Start the car and let it run until all the solvent is gone from the canister.

Unless you are mechanically minded, other DIY methods of cleaning injectors are not recommended, as they can be dangerous and result in engine damage. If your injectors still don’t work after the cleaning kit, they are likely clogged and need professional cleaning.

closeup of car injection system

Final Thoughts

Testing and cleaning your fuel injectors in an important piece of maintenance for your vehicle’s engine—but, as always, prevention is better than cure. If you are not using premium fuel for your vehicle, it is advisable you periodically add a cleaner to your gas tank to prevent buildup from occurring.

If you continue to notice your car performs poorly, it is likely your injectors are worn and need replacing. The best course of action is to take the injectors to a mechanic for bench testing to determine the extent of the damage. Purchase durable, reliable fuel injectors to avoid any future performance problems.


Demystifying the EGR Diesel System

EGR part in use inside car

If you’re not a car enthusiast, you’ve probably only heard the term EGR when the local mechanic was giving you bad news about the repairs required to fix your vehicle.

It likely went something along the lines of, “Your EGR valve is having problems,” or “You need to change your EGR sensor.”

When it comes to either diesel engines or motors, EGR systems are a key component in increasing gas mileage and lowering carbon and CO2 emissions, all while lowering the working temperature of your engine.

If you like cars, you should know all about the EGR diesel system, how it works, and why it is used in 99% of diesel engines produced by automotive manufacturers.

What Exactly Is an EGR Diesel System?

EGR stands for “Exhaust Gas Recirculation.” Contrary to what you might imagine, this is a very simple process of recirculating part of the exhaust fumes back into the power stroke.

In layman’s terms, it means what would normally come out of your exhaust pipe is sent back into the engine to get burnt again—re-using the same air and diesel a second time around.

Why Use an EGR System?

There are a few different reasons to consider an EGR system. The first reason concerns pollution.

When your diesel engine compresses the diesel and creates combustion, not all the diesel gets burnt off. To avoid excess diesel-infused CO2 from entering our atmosphere, the system is designed to recirculate some of the exhaust.

The recirculated diesel is burned along with the unused diesel to get a cleaner burn, preventing global warming, smog, and a whole host of other environmental problems. This is done by using more of the diesel that would have been wasted out of the exhaust pipe, thus causing less pollution.

close up of used car EGR

It’s Efficient

The second reason for the system is efficiency. With the rising prices of fuel and the costs associated with burning fossil fuels, the less you waste, the cheaper it is, in terms of fuel costs.

The EGR uses less fuel as part of the combustion, as the diesel/air mix is partly used exhaust fumes, rather than 100% fresh fuel. By adding up to 50% exhaust back into the system, you need less diesel to cause the combustion that powers the motor, saving you money and fuel.

Doing this allows the computer to control the heat and get more efficient use out of the engine. This results in a lower running temperature and better efficiency. Consequentially, an EGR is sometimes called an “EGR cooler” when referring to the overall system.

These days, every major diesel car or truck manufacturer is using an EGR system in their engines. Ford introduced it in the late 1970s on their bigger model pickups and commercial fleet vehicles. Since then, all other major manufacturers have incorporated the idea and concept in some form.

With the help of EGR systems, the heavy polluting diesel engines of our youth are now much more environmentally friendly and can produce up to 60% fewer carbon emissions, though that’s still not a mandatory requirement in vehicle and engine production worldwide.

EGR valve isolated

EGR Regulations

EGR systems are regulated and mandatory in most developed countries, including Canada, the U.S., the UK, and Europe. They are not used in older models and developing countries where the rules governing pollution by vehicles are less regulated.

The EGR systems for large trucks and pickups now come with a huge degree of customization based on personal preference and need. In some cases, people opt to add additional aftermarket or performance versions of EGR systems to their trucks, cars, and buses.

Aftermarket performance EGR systems are some of the most sought-after custom jobs that enthusiasts make to their diesel truck engines, and, in most cases, come combined with ram air or super chargers. These systems are specially designed to increase power and/or efficiency.

Final Thoughts

Most diesel engines in the trucks and SUVs we love to drive wouldn’t meet federal pollution and fossil fuel guidelines without their EGR systems. As the world continues to become more polluted, we can still enjoy our big trucks without losing power or having to pay more taxes for our workhorse vehicles.

What fun would your F350 be with a 3.0-liter engine or, worse yet, a fully electric one? It would lack the power required to tow, haul, or move our goods and equipment.

There is nothing more exciting than the throaty growl of a diesel engine as it thunders under the hood of your truck. EGR systems help to make them more efficient, convenient, and responsible to both our pockets and our environment!