How to test your fuel Injector? A complete guide

Whether on a TBI, throttle body injection, or an EFI, electronic fuel injection system, testing your fuel injector is an easy process. the modern fuel injector system works more efficiently and is more reliable than the carburettor model used in the past. However, it is common for this system to get common problems. The good thing is that by using simple tools and equipment, you can diagnose your fuel injector at home(Fuel Injector Tester).

Fuel injector system

In the past, cars used to have carburettors in them, but modern cars are now manufactured with the modern fuel injector system that works more efficiently and reliably. The purpose of the fuel injector system is to provide the optimum flow of air and fuel to the combustion chamber for better performance of the engine. The modern fuel injectors system has a cylinder head for better control over the air-fuel mixture under any condition. With time, the build-up from the fuel impurities or external debris may cause issues in this system. A fuel injector tester is used to test the issues because these mechanical or electrical injector system problems may contribute to rough idling, misfires, the poor performance of the engine, fuel economy and even harmful emissions. To stay safe from major issues and spend more money on repairing or replacement, it is important to check the fuel injector once in a while.

How to test TBI injectors?

Inspecting and diagnosing problems in TBI injectors is easy as you can inspect them visually using simple tools. It is the first and easy method you can use to test your fuel injectors at home. In order to check the fuel spray, you need to follow these steps:

  • Take the cover off
  • Start the engine or crank if it does not start
  • Inspect the fuel spray and check the spray pattern coming out.

While inspecting the fuel spray, it is normal to observe fuel coming out partially atomised in an inverted pattern. However, if you notice an irregular pattern or solid spray, it means your injector is broken or is dirty. To fix a dirty fuel injector, adding a high-quality cleaning additive is an effective way. You can also take your vehicle to a garage for professional cleaning.

How to test the EFI injector?

The electronic fuel injection EFI system is different from the TBI as it does not have accessible spraying. So, you cannot inspect the spray pattern visually. Moreover, the structure of the fuel injector system in EFI is so complicated that there is no room for visual inspection of the injectors. Therefore, in order to inspect the system, the complete system needs to get disassembled. To check this system, you need to use some tools or get professional help. There are a few tests you can perform to check if there is an issue within the injector. For this purpose, you need to notice the signs and symptoms of faulty fuel injectors. Here are the steps you need to follow

  • Start the vehicle and let it idle for a few minutes.
  • Press the brake and open the hood for inspection.
  • Listen to the clicking or cranking sounds inside the fuel injectors.
  • If you hear a clicking sound, it means the injector is working well because the sound produces because of the opening and closing of the valve.
  • If you hear no sound coming from inside the fuel injector system, it means the solenoid is broken or you have a dead fuel injector. In this case, the computer does not send the pulse signal, which indicates there is an issue.
  • Repeat the same procedure on other injectors to make a note of the dead injectors. Then, to know what to do with the problem with the injector, you can perform a test.

Checking dead injector

To test the dead injector, you can check the injector’s coil as it is the first step you can do. You will need to have the resistance value for the coil inside the injector and a multimeter. Your car manual will also help you know the resistance value. In case you are unable to find out, you can also check it online. First, turn off the vehicle, remove the connector and put the digital multimeter to the right value. Investigate the electrical terminals. The resistance reading indicates that you need to replace the injector.


The fuel injector system plays an important role in the vehicle as the injectors spray fuel into the engine cylinders. In these cylinders, the fuel is mixed with air to create power. Since the fuel injectors are subjected to high pressure and high temperature, there can be consequences that can cause the engine to run badly or even stop running at all. To avoid these potential issues, keep checking the fuel injectors is essential. The easy ways given in this article will help you check the fuel injectors and keep them functional and in good condition.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button