Fuel Injector Buyer's Guide
- The fuel injector is a fuel delivery component that’s responsible for spraying gasoline or diesel into the combustion chambers.
- The number of fuel injectors depends on how many cylinders are in your engine.
- The injectors are controlled by the computer, which magnetizes the electromagnetic coil to open the valve. In contrast, the valve closes when the computer cuts the supply of electric ground and lets the metal spring to relax.
- The two main categories of fuel injectors are top-feed and side-feed.
- Top-feed fuel injectors are subdivided into three: regular, hose-end, and direct.
- Side-feed fuel injectors have two subcategories: throttle body injectors and manifold side-feed injectors
- In an ideal setting, a fuel injector should last anywhere between 50,000 and 100,000 miles.
- Fuel quality and fuel filter maintenance determine how long your fuel injectors are going to last.
- A fuel injector costs around $15 to $655.
What is a fuel injector?
The fuel injector is a fuel delivery component that’s responsible for spraying gasoline or diesel into the combustion chambers. It’s simply a special valve designed to receive and deliver fuel to the cylinders. It is electronically controlled to fully or partially open and close depending on the data collected by various sensors in your vehicle.
The number of fuel injectors depends on how many cylinders are in your engine. A six-cylinder engine or a V6 has six injectors assigned per cylinder. They are installed suspending from a slim bar called the fuel rail which runs along the top or side of your engine block.
How does the fuel injector work?
Fuel injectors are powered the moment you turn the ignition switch on. That, however, is an incomplete circuit so the small valves remain close. The circuit will only be completed if the computer sends signals in the form of an electrical ground that activates the electromagnetic coil. Once magnetized, the coil will pull the valve’s sealing mechanism, allowing the fuel to flow through the injector right after passing the fuel filter.
In contrast, the valve closes when the computer cuts the supply of electric ground and lets the metal spring relax. This return spring is what forces the sealing mechanism (either a pintle, a ball, or a disc) to shut and cut the fuel supply. This cycle of opening and closing the valve happens at an extremely fast rate or hundreds of times per minute.
Types of fuel injectors
Since there are different types of fuel injection systems, you’ll find a diverse selection of fuel injectors in the market. Below are the most common types of fuel injectors depending on the application.
The top-feed type usually has the fuel inlet provision on the top and uses a vertical fuel flow that runs from top-to-bottom. There are three subcategories of top-feed injectors: regular top-feed injectors, hose-end injectors, and direct fuel injectors.
Regular Top-feed Injectors
This is the type that uses a common fuel rail that mounts the top of the injectors. The connection is sealed either by an O-ring or an injector clip depending on the design. Meanwhile, another O-ring seals the connection between the intake manifold and the injector.
Hose-end injectors feature a rubber hose that connects it to the fuel rail. The hose is held in place by a clam an is directly inserted to the injector’s ferrule. This type of top-feed injector is commonly found on older vehicles. Hose-end injectors were deemed unreliable because the rubber hose has the tendency to become brittle and crack due to temperature changes.
Direct Fuel Injectors
Direct fuel injectors use a common fuel rail and heavy-duty O-rings that seal the point between the fuel rail and the injector. They inject highly atomized fuel into the combustion chambers under high pressure.
Direct injectors operate at pressures 450 to 3000 PSI. The typical pressure at which top and side-feed injectors operate ranges from 38 to 100 PSI.
Side-feed injectors are more compact than top-feed partly because they fit inside the fuel rail. The main difference between top-feed and side-feed injectors is that a side-feed fuel injector has the fuel entering from the holes at the side instead of on the top. Since it fits inside the fuel rail, the injector is submerged in fuel for the most part.
There are two subcategories of side-feed injectors: throttle body injectors and manifold side-feed injectors.
Throttle Body Injectors (TBI)
This type of injector is used in single-point injection systems. It is located in the same area where the carburetor used to sit. Depending on the size of the engine, manufacturers fit one or two of this, while aftermarket setups use up to four. This is rarely used nowadays as injectors are becoming closer and closer to the cylinders.
Manifold Side-feed Injectors
As the name implies, this type of side-feed injector is located in a common fuel rail that’s mounted on the intake manifold, close to the cylinder head. It features two O-rings that are found on the top and between the fuel rail and cylinder head.
Multi-port fuel injector
Multi-port fuel injectors are more advanced than single-port, throttle-body injectors. These injectors spray fuel simultaneously into the cylinders, and they are highly efficient in metering gas into the engine, resulting in better, more precise fuel delivery. Multi-port fuel injectors don't come cheap, but they do offer more power and greater fuel economy. If you want to enjoy these benefits, then you must be willing to pay the price and shell out more money.
Sequential multi-port fuel injector
Sequential multi-port fuel injectors are the most advanced and offer the most precise fuel delivery. Each injector is programmed to spray fuel to a particular cylinder right before it fires unlike the multi-port, which delivers fuel simultaneously. Quicker response, better fuel economy, and greater power per stroke are just some of the benefits of this type of injector. However, this can be quite heavy on the pocket, so you have to weigh the pros and cons first before purchasing it.
When to replace your fuel injector
In an ideal setting, a fuel injector should last anywhere between 50,000 and 100,000 miles. This specification, however, is affected by the type of fuel you use and how regular you replace various fuel filters. Low-quality fuel can cause carbon deposits to accumulate and clog your fuel injectors. If this happens, you’ll experience problems like lean fuel mixture, troubles in turbocharging, and engine detonation or knocking.
Also, be cautious about externally leaking fuel injectors as they can light your car on fire.
Signs of a bad fuel injector
Faulty fuel injectors can damage your engine if the problems pile up. Make sure to deal with it as soon as you find out about it. To be able to do that, take note of the bad fuel injector symptoms you may encounter if your injectors are in bad shape.
- Ignition difficulties
- Wild engine vibration
- Degraded performance
- Poor or rough idling
- Knocking or spark plug detonation
- Poor fuel economy
- Failed emissions test
- Difficulties reaching high RPM
- Strong gasoline or diesel odor inside and around the car
- Oil thinning
- Thick smoke coming from the exhaust
How much is a fuel injector?
OE fuel injector replacements on CarParts.com consist of remanufactured and new assemblies from reputable brands. A fuel injector costs around $15 to $655. You can purchase individual pieces or a package of up to a set of eight. Filter your search by selecting your preferred OE replacement brand, series, or by simply indicating your vehicle’s year, make, and model.
How to Replace Your Fuel Injector
Fuel injectors deliver a precise amount of fuel to the cylinders for optimum fuel combustion. This pressurized fuel is necessary to keep your engine running at peak operating performance.
Damaged fuel injectors will not be able to spray fuel into the combustion chambers properly, creating an imbalance in the air/fuel mixture. This can affect the engine's operation, so you need to replace a busted fuel injector right away. Here are the tools you'll need and the steps in replacing a damaged fuel injector:
Difficulty level: Difficult
Tools that you need:
- Flathead screwdriver
- Allen socket
- Fuel injector puller
- Open-end wrench
- Safety glasses
- Protective equipment (gloves, closed-toe shoes)
Step 1: Start by disconnecting the fuel pump relay and main fuel line. Discharge the fuel lines first for safer fuel injector removal.
Step 2: Loosen the screws holding the fuel rail connector to the engine block. Disconnect all wiring connected to the rail and tug it away from your fuel injectors.
Step 3: Unclip the electrical wiring connected to the busted fuel injector. Using a fuel injector puller, pull out the said fuel injector. You can do this by sliding the puller underneath lip in the housing and popping out the injector.
Step 4: A hole is left open in the intake manifold once the damaged fuel injector is popped out. Leave it open but don't let anything fall inside it. Be very careful with the open hole, as this will require additional repair work if it gets damaged. Give the new injector seals proper lubrication first before you install them.
Step 5: Place a new fuel injector inside the hole. Reconnect all wirings and tighten the screws back in place. Reconnect the main fuel rail to the engine block. Do a road test to confirm if the fuel injectors were installed correctly.