Test Fuel Injectors

How To Test Fuel Injectors? Easiest Tips & Tricks

What Is An Injector?

In order for an engine to run smoothly and efficiently, it needs the right amount of fuel/air mixture. The amount of fuel/air mixtures varies depending on the size and design of the engine. Traditionally, this responsibility’s delegated to the carburetor. However, with time a better alternative arrived – the fuel injector.

Fuel Injectors vs Carburetors

The main difference between fuel injectors and carburetors is that the former uses valves and the latter a tube. Carburetors create a vacuum via the tube which pulls in the fuel. Meanwhile, fuel injectors use two valves – choke and throttle. The choke helps the engine to run lean by decreasing the amount of air and increasing the flow of fuel. Furthermore, the throttle valve regulates the fuel/air flow to the engine. The openness of the throttle determines the acceleration of the vehicle.

In the fuel injector vs carburetor debate, the former wins the race. Especially, the introduction of Electronic Fuel Injectors has ceased any debate.

Fuel Injector: A Guide

Well, the question remains. “How do fuel injectors work?”. Apart from its definition, the working of a fuel injector’s complex. In today’s age, a fuel injector has become an integral part of every vehicle. This is primarily because the principles of combustion dictate that the better the quality of the air/fuel mixture, the better the combustion. This results in better engine efficiency and lower emissions.

Since its inception, the prolific run of injectors has led to heavy investment in its advancement. With time, 2 types of injectors came to the front. Diesel and gasoline fuel injectors

> Gasoline Fuel Injector

Gasoline fuel injectors spray gasoline directly, through the intake manifold, or throttle body. Then, the spark ignites the injection in the combustion chamber for combustion. We can further differentiate between these designs. The contemporary direct gasoline injector uses a multi-nozzle hole. Whereas, the intake manifold and throttle body utilize a pointless nozzle.

> Diesel Fuel Injector

Diesel fuel injectors spray diesel directly into the combustion chamber. Once sprayed, compression ignition takes place in the diesel engine’s combustion chamber. The difference between this injector and a gasoline fuel injector is that the former requires a higher injection pressure.

Fuel Metering

Fuel injectors play a part in fuel metering as well. The latter controls the duration of the injection quantity, pressure, and timing of the fuel. To this end, 2 routes exist.

> Mechanically Controlled Fuel Injectors

In these fuel injectors, the springs and plungers manually control fuel metering. These parts take input from the cam or fuel injection pump.

> Electronically Controlled Fuel Injectors

On the other hand, the other type of fuel injector electronically controls its functions. The electric solenoid takes the input from Electrical Control Module (ECM).

Testing Fuel Injectors

Granted, fuel injectors go through multiple complex processes in their construction. This propels many people to think that only a trained hand can test it. Although true in many cases, there are many instances where a DIY approach is adequate.

> Look For Signs

It’s wise to look for any clues that indicate that the injector’s compromised. The signs of a bad fuel injector include but aren’t limited to the engine misfiring, stalling, or a rough idle. However, these symptoms may be the result of another problem as well. Hence, it’s best to get a second opinion.

> Test The Spray Pattern

The first test that you must run is to visually observe the fuel spray. In order to do that, take the cover off the air cleaner housing. Then, ask someone to start the engine. Observer the spray pattern that comes out of the injector. If the resultant pattern is in a V-shape, then the fuel injector’s fine. However, an irregularity in shape and spray is likely signally a malfunction. Moreover, it is a major red flag if no fuel is sprayed out.

> Listen To The Clicking

Electronic fuel injectors are more complex than their analog counterparts. Thus, it makes it difficult to examine it yourself without compromising its structural integrity. However, there is a way to test it.

First, get yourself a mechanic’s stethoscope or similar equipment. Then, press the parking brake and open the hood after starting the vehicle and letting it die. Subsequently, listen to the noise inside the injector using the earpiece. If you’re hearing a clicking sound from the inside, then all is well. However, the absence of any sound means there is something wrong.

> Checking A Dead Injector

In case of a dead injector, check the injector’s coil. In order to run this test you’ll need a multimeter and the resistance value of your coil. Once obtained, remove the electrical connector of the injector after turning off your car. Put the digital millimeter to the same value of your coil’s resistance. Then, investigate the injector electrical terminals. If your resistance reading differs from the specified reading, then that’s the signal to replace your injector.

Bottom Line

At the end of the day, checking fuel injectors can be a tricky task. However, instead of going to the mechanic for every inconvenience, make sure you go through a few DIY methods first. This will not only educate you on the workings of your car but limit the possibility of any scams.

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