Fuel Injection Kit Buyer's Guide
- A fuel injection kit is a selection of components that work together to deliver the right amount of fuel to the engine at the right time.
- Each kit may include a combination of the following parts: fuel rails, throttle body, injectors, fuel pressure regulator, wiring harness, O2 sensor, MAP sensor, IAT sensor, TPS sensor, and IAC motor.
- Fuel injectors are mounted on the intake manifold and spray atomized fuel into each cylinder via a port before each intake valve.
- The engine computer uses data from various engine sensors to determine how long these injectors should stay open to achieve the optimal air-to-fuel ratio for engine performance.
- There are two main types of fuel injector systems: throttle body and port fuel injector systems.
- Throttle body or single-point fuel injection systems metered out fuel to multiple cylinders from a single injector in front of the intake manifold.
- Port fuel injector systems can be classified into two: multiport and sequential fuel injection systems.
- The cost of a fuel injection kit may vary depending on the year, make, and model of your vehicle. In general, OE replacement fuel injection kits will cost you anywhere between $1,000 to $4,500.
- A failing fuel injector system may cause an engine misfire, rough or poor idling, strong fuel odors, and reduced fuel economy.
Fuel injection systems have been around since the mid-50s. European vehicles adapted this technology which was originally used in wartime airplanes. It was the stricter emission standards of the 80s that led automakers in the U.S. to replace carburetors with a system that lets the engine run more efficiently. Since 1990, all vehicles manufactured for use in the U.S. have been equipped with fuel injectors.
If you’re looking for a replacement fuel injection kit for your vehicle, here are a couple of things you should know.
What is a fuel injection kit?
A fuel injection kit is a selection of components that work together to deliver the right amount of fuel to the engine at the right time. These parts ensure that the engine runs efficiently, and at the same time, produces minimal vehicle emissions. Each kit may include a combination of the following parts: fuel rails, throttle body, injectors, fuel pressure regulator, wiring harness, O2 sensor, MAP sensor, IAT sensor, TPS sensor, and IAC motor.
How do fuel injection systems work?
To understand how fuel injection systems work, there are two principles that you should know. The first is that the relationship between vehicle power and fuel consumption is directly proportional. The second one is that a proper air-to-fuel ratio must be achieved for optimal engine performance.
When you depress the gas pedal, the throttle valve opens and allows more air into the engine. Engine sensors detect this change and send a signal to the engine control unit or ECU. This prompts the latter to alert the fuel delivery system to pump more fuel towards the engine to maintain the optimal air-to-fuel ratio for combustion.
The fuel injectors are connected to fuel rails that supply the pressurized fuel delivered from the tank. These injectors are mounted on the intake manifold and spray directly into a port before the intake valves. As it receives a signal from the ECU, the electronically controlled valve opens and squirts a fine mist of fuel that is mixed with air and burned in the combustion chamber. The engine computer determines how long the injectors must spray into the engine, controlling the amount of fuel burned in the combustion chambers.
Types of fuel injection systems
There are two main types of fuel injector systems: throttle body and port fuel injector systems.
Throttle body fuel injection systems
This system was the first type of fuel injection system to replace carburetors. It is also called a single-point injection system because similar to its predecessor, it metered out fuel to multiple cylinders from a single injector in front of the intake manifold.
This type of fuel injection system was later replaced because the design caused fuel to pool in the intake manifold. The air-to-fuel mix that it delivered was also not consistent. Cylinders closer to the injector got a richer mixture, while those farther away received a leaner mix.
Port fuel injection systems
These systems were designed to have separate injectors for each engine cylinder. Atomized fuel is sprayed into a port located before each cylinder’s intake valve. This is where fuel is mixed with air before they are pulled into the combustion chamber for burning. Most modern vehicles are fitted with this type of fuel delivery system.
Multiport fuel injection systems
A multiport fuel injection system activates one group of fuel injectors at a time. One major disadvantage of this type is that a problem in the system can cause misfires to occur in multiple engine cylinders
Sequential fuel injection systems
A sequential fuel injection system sprays fuel into the intake valve by firing each injector individually. This type of system has better control over pulse width or the amount of time that the injector stays open.
How much is a fuel injection kit?
The cost of a fuel injection kit may vary depending on the year, make, and model of your vehicle. In general, OE replacement fuel injection kits will cost you anywhere between $1,000 to $4,500. Since this kit involves the installation of critical parts on and around the engine, we strongly recommend seeking the help of a licensed mechanic to ensure that all components are properly fitted and installed.
What are the signs of a bad fuel injection system?
The parts of a fuel injection system rarely wear out on their own. In the case of fuel injectors, problems typically arise when contaminated fuel enters the system. If you notice one or more symptoms below, it may be time to take your vehicle to a trusted mechanic.
Engine misfire and poor idling
A damaged fuel injector may cause an engine misfire or uneven idling. You may feel the engine sputtering or shaking when stopped at a traffic light. This can cause serious damage to the engine if ignored.
Noticeable fuel smell
A fuel injector that has a faulty valve may cause fuel to leak. If you notice a strong fuel smell in the engine bay, you may need to have your vehicle’s fuel injectors checked.
Reduced fuel economy
A sudden increase in fuel consumption can be a sign of a failing fuel injector that is no longer capable of atomizing fuel into a fine mist. A similar issue can also be caused by a sticking valve or faulty engine sensors.
Finding the right fit
Let CarParts.com help you find the right fuel injection kit with our website’s built-in vehicle selector. We’ve made it easier to purchase the right parts that are guaranteed to fit your vehicle. Simply select the correct year, make, and model of your vehicle to browse our selection of high-quality kits today.
DIY Car Maintenance: Cleaning with a Fuel Injection Kit
Fuel residue or foreign matter left in the fuel injection system can cause very poor vehicle performance, including dips in fuel efficiency and rough idling. To remedy such problems, turn to your handy fuel injection kit. This kit cleans out the gunk that accumulates in the ducts of the fuel injection system. It's recommended that you clean this system every 25,000 to 30,000 miles to guarantee maximum fuel efficiency. Here's how to do it:
Difficulty level: Easy
What you will need:
- Owner's repair manual
- Fuel injector kit
Step 1: Open up the hood and prop it open. Make sure that your engine is off while you're doing so.
Step 2: Detach the pressure regulator and hook up your cleaning kit to the port on the fuel rail.
Step 3: Unscrew the gas cap, which will in turn reduce the chance of excess pressure build up within the system.
Step 4: See to it that the fuel pump is turned off. To test if the fuel pump is on or off, try starting the engine. If it won't start, that means the pump is off.
Step 5: Determine the appropriate fuel pressure reading for your vehicle by referring to your owner's manual.
Step 6: Open the valve on the fuel injector kit until you reach the proper fuel pressure reading for your ride.
Step 7: Start your engine and keep it on for about five minutes or until the solvent container is empty. Your engine will shut down at this point.
Step 8: Place the fuel pump switch back into its normal position and screw on the gas cap.
Step 9: Uninstall the injector kit and attach the pressure regulator.
Step 10: Reattach your fuel pump and unplug the fuel return line.
Step 11: Turn on the engine and place a long screwdriver on the fuel injectors. Place the handle up to your ear and listen for a rapid clicking sound. This sound is an indication you're your injectors are in proper working condition.