How To Clean Fuel Injectors

Providing a consistent mix of air and fuel to your cylinders for combustion, fuel injectors are an integral part of what makes the engine in your 4x4 work. They’re also key to the efficiency of your vehicle and are constantly under pressure, so it’s important to pay attention to them if you want to get the very best performance. 

No matter what make or model 4x4 you own and regardless of whether you have a diesel or petrol engine, fuel injectors are always present. So, this month at Milner Off Road, we wanted to talk to you about dirty and clogged fuel injectors, how they impact performance and how you can go about looking after them.

Signs of dirty or clogged fuel injectors

If you’ve got dirty or clogged fuel injectors, it might be hard to know their condition without taking a look under the bonnet and removing each injector one by one. However, there are a few signs of fuel injector issues that you can be on the lookout for if you conduct some regular checks and maintenance.

• Leaking fuel - You’ll either see the fuel when you open your bonnet or you’ll be able to smell it. This is an obvious sign of a cracked or blocked fuel injector.
• Lower mileage - A tricky thing to gauge, but if you pay keen attention to how many miles you usually get after filling up and notice that mileage level dropping, then it could be due to poor performance from your injectors.
• Inconsistent drive - When an injector pumps too much or too little fuel into the engine, you’re likely to see issues with starting the ignition or surges while you’re driving.
• Inconsistent RPM when idling - Possibly the easiest way to spot a fuel injector issue is if your engine’s RPM gauge fluctuates while idling, indicating an issue with the supply of fuel.

What happens if fuel injectors are clogged?

When your fuel injectors become dirty or clogged, several things can happen. Firstly, the issue of clogging can simply mean that not enough fuel is being injected into the cylinder from the fuel rail; this results in less power and less efficiency. When your injector filter becomes dirty, usually due to rust getting in there, it can also impact performance, either breaking the component or creating a leak elsewhere.

If your fuel injectors are constantly spraying, this might indicate that there is an electrical problem with the component instead.

How do I clean fuel injectors?

The good news is that there are several ways in which you can clean fuel injectors on a 4x4. The first and safest method is to visit your local garage where they can test, diagnose and - if there is an issue - clean your fuel injectors professionally. 

If you want to tackle this issue yourself, we strongly advise that you only do so if you follow safety precautions and have the right tools and experience. Diesel injectors, in particular, work under extreme pressure, so never put your hands near while they are running.

Here are a few basic steps to follow:

1. Find your fuel injectors and the fuel pump, then disconnect the injectors from the pump and disconnect the pressure regulator.
2. Connect a fuel injector cleaning kit via the fuel port — don’t forget to remove the fuel tank cap to avoid a pressure build-up.
3. Start your engine to trigger and put the cleaning solution into use. This might cycle for anywhere between 5 to 10 minutes, then you can turn your engine off again.
4. Disconnect the fuel injector cleaning kit and reattach the fuel pump and pressure regulator.
5. Start your engine again to check if any of the symptoms persist.

​Again, we only recommend tackling this if you know what you’re doing, otherwise you should contact a professional.

If your fuel injectors still display issues after this, you might want to consider replacing them with new ones to ensure the best performance of your vehicle.

How often should fuel injectors be replaced?

With regular cleaning and maintenance, fuel injectors should last for at least 45,000 miles. However, the length of time that your fuel injectors will last will vary depending on the make and model, so there isn’t a definitive answer to this question. 

If you need new fuel injectors for your 4x4, look no further than Milner Off Road. We supply injectors, primer pumps and suction control valves for 4x4 owners around the world so that you can get the parts you need, when you need them.