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Vehicles have complicated electronics. When fixing a vehicle, knowing where to look is a start, especially when learning about power and your fuel injectors.

The average car electronics setup controls many parts of your vehicle. They also use a variety of methods to keep your fuel systems running safely and efficiently.

The fuel injector is somewhat uniquely controlled by a combination of a fuse, an electronic wire, and the ECU, or electronics control unit. A vehicle's fuel injector will pulse on and off using the ground wire to cause gas to be injected or to stop the flow.

We'll discuss where power comes from in your vehicle, how the fuses work, and what to do in the event that the fuel injection system stops working.

We've worked with mechanics and done our research. We'll dive in and explain how the fuel injector is powered – so you can do something about it.

Table of Contents

About fuel injectors

Most people who are wondering how a fuel injector is powered are either dealing with a mechanical issue in their vehicle, or are generally trying to learn about cars. You might also be looking at a wiring diagram for your vehicle, somewhat confused by all the wires and parts laid out.

Briefly, the fuel injectors themselves take a feed of fuel from the fuel pump at a certain pressure, and spray it into the combustion area, where it can be used to power the engine. The injector works precisely, and also makes the gasoline presented into a fine mist that is more easily made combustible within the engine.

So what makes this work?

The fuel injector is connected to the electronics control unit, which is basically a wiring harness attached to a circuit board. Given how reliant vehicles are upon electronics, the ECU amounts to the brains of the entire vehicle. The ECU helps coordinate electronic signals to all powered parts to deliver the energy needed, at the right time.

The ECU connects via wires to a fuse that is often located under the hood. The fuse itself has the primary purpose of protecting the electronic units within the vehicle from either an excessive amount or power, or a lack of power.

Power is provided via one of these wires, which has a “hot” wire and a ground wire that conducts electricity to a harmless base in your vehicle. Within your vehicle, it is possible that your ECU turns off the ground wire very quickly to signal power to the fuel injector.

I have a problem with my fuel injector, I think. Where should I start?

Your problem could be a bad fuse, a bad wiring harness, or a bad wiring relay.

Start with the fuse

While vehicles don't blow fuses often, they are one of the easiest parts to fix on a vehicle. Check your vehicle manual to see where the fuse box is located under the hood. You may want to consult an additional diagram about your vehicle to know where the specific fuse is for your fuel injector. A small pliers (or even your fingers) could be useful to remove the fuse itself and check it. A good fuse will visible show the connection between two wires and not appear burned. A bad fuse has a broken connection and can look visibly burned. A burned fuse can also be an indicator that the ECU and battery are somehow sending too much or not enough electricity.

If the fuse is bad, find the part number and replace it!

Check the power cables

There are power cables leading from your ECU and fuse box to the fuel injector. First, check to see what range of voltage/amperage should be present on the wire. Use a multimeter to see how much electricty is coming through. If you aren't getting a reading and the fuse is working properly, you might just have a bad wire. Replacing a wire isn't quite as easy as replacing a fuse, but it's relatively inexpensive.

Wiring harness

The wiring harness can be the least fun to work with, and is our last step. There can be an issue within the wiring harness – like loose connections or broken cords, that cause the connection to the fuel injector to be bad.

Can the fuel injector itself also go bad?

It's possible. Test the fuel injector by using an ohmmeter on either terminal on the fuel injector and see if the readings fall within normal guides. If they don't, the injector itself might need replacing.

Fuel injector problems


Fuel injectors act as a pass through for fuel, so they might become clogged over the course of your vehicle's lifetime. Removing a clog can be fairly simple, including the use of fuel system cleaners that break up carbon deposits. Clogging is most commonly caused by using aged or low quality fuel that eventually gels up or doesn't burn completely. Prevent clogs by not storing gas in your tank for an excessive amount of time and by using high quality fuel from your gas station.

A clogging fuel injector won't necessary stop your engine completely, but it can lead to obvious under performance because the injector is unable to deliver the amount of fuel needed.

Can bad fuel injectors stop my engine?

Unfortunately, they definitely can. A completely clogged fuel injector or unpowered fuel injector stops your engine from receiving any fuel, so the engine won't start or run. This is not an especially common problem though as most fuel injectors last for the life of the vehicle.

How do I maintain my fuel injector?

The honest answer here is to use fuel system cleaner at some intervals. Otherwise, you can readily leave your fuel injector alone to do it's work, and you'll probably never notice it.

How much does it cost to replace a fuel injector?

The answer depends entirely on the vehicle. A larger performance engine will probably exceed $1000 with parts and labor while smaller engines with smaller injectors might run in the $350 to $500 range. One potential positive about replacing fuel injectors is that besides stopping the engine, they are unlikely to cause a catastrophic chain of problems within the engines parts.

Can an ECU issue make the fuel injector do weird things?

The ECU has a major impact on how the fuel injectors work because the ECU all but tells the entire engine what to do. The electronics control unit is busy calculating the driver's input and the vehicle's speed – and a series of math that could be the subject of another article all in itself! To simplify: The wrong math can throw off a fuel injector and make the vehicle underperform.

What Sends Power To Fuel Injectors?

About The Author

Charles Redding

Charles Redding

I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.

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