How to Detect and Fix Clogged Diesel Fuel Injectors?

The performance of a diesel engine is often closely linked to the condition of its fuel injectors and injection system.

Modern trucks and diesel vehicles have advanced and complex diesel injection systems. Vehicle owners should regularly check these systems according to the manufacturer’s recommendations to ensure they perform optimally.

Clogged fuel injectors can cause multiple challenges and negatively impact your vehicle’s ownership cost. 

This blog discusses the importance of fuel injectors and their maintenance, troubleshooting, and testing methods for servicing clogged fuel injectors. 

Diesel Fuel Injection

Diesel fuel injection systems in modern-day automobiles are technologically advanced. They are designed to ensure proper fuel delivery from the fuel tank to the combustion chambers. Let’s look at some of the main components of the system.

• Tank: The fuel tank acts as a storage for the fuel. It comes in varying capacities based on the type of vehicle and application.
• Fuel Filters: Diesel fuel may contain contaminants and residues that must be filtered before it can pass through pumps and injectors. Filters ensure that the contaminants in the fuel are removed before they are distributed to the other components.
• Fuel Pump: The pressure at which the fuel is injected into the cylinders determines the effective performance of your vehicle. Diesel fuel must be pressurized from atmospheric pressure to very high pressure (sometimes up to 30000 psi).
• Interconnecting Pipes and Tubes: These help in transporting the fuel from the tank to all other parts of the injection system.
• Injectors: Injectors are the final component in the system. They atomize fuel and inject it into the combustion chambers at very high pressure, in the right quantities, and at the right time.

Diesel Fuel Injector

A relatively smaller component that has a major say in the performance of your diesel vehicle. It is a technologically advanced part made of special materials to withstand higher pressure and higher temperatures. 

It receives signals from the vehicle’s Electronic Control Unit or ECU and injects the fuel into the cylinder through its nozzle in an atomized form (like a mist). 

A fuel injector is a single part made up of several functional components built within it. The core components of a common rail electronic fuel injector (EFI) are:  

• Needle valve
• Solenoid coil
• Nozzle

Why Do Injectors Fail?

Here are the main reasons why injectors fail:

1. Particle contamination: Though fuel filters in vehicles are supposed to remove contaminants, sometimes very small-sized particles in microns (1 micron = 0.001mm) can pass through them. 

Over time, the contaminants can clog the injector. In some cases, the contaminants could solidify and clog the sealing surfaces within the injector.

2. Water Contamination: Excess Water in the fuel is also a contaminant that can cause corrosion of the fuel delivery components. The corrosion of sealing surfaces within an injector can negatively impact its performance.

3. Deposits: Fuel left in the injector after the engine is shut down can solidify due to engine heat creating carbon deposits known as coking. The carbon deposits can clog the nozzle or the sealing area of the needle valve, disrupting fuel delivery.  

4. Incorrect Installation: Poor installation of fuel injectors and the adoption of incorrect practices while installing them can result in an injector missing a few components, like washers and seals. The missing parts, though small, can have a big impact on the injector’s performance.

Symptoms of Faulty Injectors:

Symptoms of faulty injectors can significantly impact vehicle performance. Here are the key indicators to watch for:

1. Engine Misfire: When the fuel supply to a cylinder is disrupted due to clogging of the injector, the vehicle may not be able to generate the rated power, causing it to misfire. The vehicle may splutter, stumble, or lose RPMs.
2. Rough Idle: Clogged or bad fuel injectors prevent the engine from getting enough fuel. So, when a vehicle is idling, the RPM may drop below the optimal value, leading to rough idle.
3. Poor Fuel Economy: When the ECU tries to compensate for the fuel not delivered to the engine by a clogged injector, excess fuel gets into the engine, leading to poor fuel economy.
4. Increased Emissions: Fuel that is not delivered in the right quantity and at the right time could lead to partial or incomplete combustion, resulting in higher emissions.

How to Test Fuel Injectors?

When you have noticed the signs of a bad fuel injector, it’s time to verify them. Here’s how you do it:

1. Test Light: Test lights are inexpensive and commonly available at local stores. To learn how to perform this test, see Testing a Fuel Injector (DIY).
2. Electrical Resistance: Using a multimeter, you can check if the resistance values of all the injectors match OE specs. 
3. Listening to Your Injectors: You can detect if the injectors are functioning properly by placing the metal end of a long screwdriver on them and keeping the other end near your ear. A distinct ‘clicking sound’ is produced by the opening and closing of the needle valve in the injector. If no sound is produced, it means the injector is not working.

When to Seek Professional Assistance

If you have tried all these methods and are still unable to pinpoint the problem, it’s time to seek help from professionals.

Note that clogged fuel injectors may not be the cause of your vehicle problems. Since there are hundreds of functional components in the engine, any of them could be malfunctioning resulting in poor performance. 

However, a trained mechanic or a professional can pinpoint the source of the problem by the process of elimination.

Diesel Components Inc. can offer comprehensive services for fuel injectors and other parts in the injection system. Operating as a family-owned firm since 1977, we have developed a reputation for servicing diesel engines and systems in the North American market.

Our service centers are equipped with injector test benches, which can perform several tests on injectors if they are found to be the source of the problem. Some tests that we perform are:

• Leak test
• Flow rate test
• Spart pattern test
• Response time test
• Electrical integrity test

Based on the test results, we can offer you an injector rebuild service or diesel injector repair option that will be executed by our OE-certified technicians. 

In addition, we can help you to decide if the injector must be remanufactured or replaced.