What will be your top priorities if you’re a diesel vehicle owner or in the process of having one? Among other things, performance and fuel efficiency will be at the top of the list. In the diesel automotive world, performance typically means optimal power output, torque, smooth idling, noise and vibration levels, emission compliance, and engine longevity.
Did you know that Diesel fuel injection systems and injectors play a significant role in all these factors?
Large OEMs like Bosch, Denso, Stanadyne, Lucas, and several others make considerable investments in R&D in the design and production of injectors and injection systems.
This blog will provide meaningful insights into injectors, their role, possible challenges, troubleshooting, and, more importantly, how to test fuel injectors.
Basics of Diesel Fuel Injection and Injectors:
Injectors are parts that spray atomized fuel (fuel in a mist form) into the combustion chamber to enable the combustion of air and fuel, which will then propel the vehicle.
The injector technology allows it to dispense the right amount of fuel at the right time and flow rate, making a complex process possible.
Overview of Fuel Injection System:
The injection system is made of
- Diesel Tank
- Transfer pump
- Fuel filter
- High-pressure pump
- Interconnecting tubes and hoses
- Fuel injectors
- Supporting accessories
The system has a low-pressure side and a high-pressure side, with fuel injectors located on the high-pressure side.
How do Fuel Injectors Work?
Injectors are precision products manufactured with high tolerances and several working components. For example, an electronic fuel injector (the preferred choice) has a needle valve, nozzle, and solenoid coil within its body and other parts like seals, poppets, plungers, and springs.
A solenoid is nothing but a coil of wire that, when energized, allows the fuel to flow into the needle valve section of the injector.
The needle valve allows the fuel to flow into the chambers at high pressures of 10,000 Psig – 30,000 Psig through the nozzle. The pressure is approximately 30,000 times higher than the atmospheric pressure at the ground level!
Signs of a Faulty Fuel Injector
If you’re a diesel vehicle owner, you could have faced some of these challenges at some point:
- Rough Idling
- Engine Stalling
- Lower power and torque delivery
- Excessive noise from the engine
- Poor fuel efficiency
- Higher emissions
Some of these may be directly attributable to fuel injectors. These are the common symptoms to watch out for.
A properly performing injection system and injector would provide optimal performance minus all the abovementioned challenges.
Understanding Fuel Injector Challenges
As per the manufacturer’s recommendations, optimal performance can be recovered when periodic maintenance is performed at scheduled intervals.
In a few cases, the engine integrity could be compromised if injectors are not periodically tested and maintained.
Dirt and other contaminants can enter the injector and interfere with its internal components’ function. Driving conditions and wear and tear could also cause problems.
As the injector components are manufactured to higher tolerances using unique materials, any damage can compromise their functioning, leading to costly repairs or replacements.
How to Test Fuel Injectors?
After determining that fuel injectors could be the source of your problem based on the signs, it’s time to start with the diesel fuel injector testing.
Sound/Vibration Test
Before you decide to clean the injectors or re-build or even replace them, perform the following tests to understand if the problems can be traced to the injectors.
Take sufficient safety precautions as you will work on the engine with its hood open.
- Pop the hood and locate the fuel injectors.
- Once you locate the injectors, place the metal end of a long screwdriver on one of them. The engine should be running to perform this test.
- You will observe the ‘clicking’ sound produced by the injector due to the opening and closing of the needle valve within it.
- When you put your ear closer to the plastic handle of the screwdriver, you can hear the clicking sound or vibrations produced by it.
- Do this for all the injectors. If you don’t hear a clicking sound or associated vibrations for any specific injector, you have located the defective injector.
Testing with a Test Light
This is a DIY method for testing your fuel injectors.
Get a test light. These are affordable and available at any online or local store. A test light comprises a lightbulb enclosed in a casing connected to two wires.
Before starting the test, take all safety precautions to avoid the risk of shock or fire.
Turn on the key, but don’t start the engine. Doing this will activate the vehicle’s electrical circuit.
- Turn on the ignition (do not start the engine).
- Attach one alligator clip to the battery negative terminal.
- Locate the fuel injectors and identify the wire carrying a constant 12V supply.
- Plug the clip into this wire. If the test light glows, the injector is functioning.
- Repeat for all injectors.
Checking the Electronic Control Module (ECM) Output
Once you have completed the above test, test the other wire carrying the electric signal to the injector from the Electronic Control Module or ECM. Think of ECM as the onboard computer that controls all the engine management aspects.
Alert: Recall that two wires are carrying electrical signals to an injector. You have already tested one of them.
- With the engine running, connect the test light to the +ve battery terminal and the clip to the ECM signal wire on the injector.
- Throttle the engine and check for a flashing light. No flash indicates a faulty injector.
If any injectors fail this test, you know the source of the problem.
Professional Assessment
For comprehensive testing, visit a service center with an injector test bench. These tests, performed in a controlled environment, include:
- Leak Test
- Fuel Spray Pattern Test
- Flow Rate Measurement
- Response Time of Injectors
- Electronic Functionality
Results from these tests help technicians determine specific issues and decide on repairs or replacements.
Conclusion
Recognizing and testing faulty injectors’ signs can save you from costly repairs and downtime. Regular testing and maintenance of your fuel injectors ensure that your vehicle runs smoothly, with improved fuel efficiency and reduced emissions.
If you want comprehensive diagnostics, expert repairs, and test fuel injectors, trust professionals specializing in diesel fuel systems. Diesel Components Inc. offers state-of-the-art testing and repair services to keep heavy-duty and on/off-highway vehicles in peak condition.
Contact us at (952) 890-2885 to schedule an appointment and keep your engines in shape.
You can also visit our professionals at Diesel Components Inc.
