How to Complete a Carb-to-EFI Fuel Injection Conversion

July 2, 2012

Switching from a carburetor to electronic fuel injection is critical for gas savings. Learn the 6-step process of EFI fuel conversion.

EFI Fuel Conversion

A fuel injection conversion replaces a carburetor with a fuel injection system. There are fuel injection conversion kits that make the entire process very easy. Older cars have carburetors, but electronic fuel injection (EFI) offers greater fuel efficiency and improved performance. One of the most difficult parts of the DIY fuel injection conversion is tuning the chip that runs the EFI.

Tools and Materials

  • A wrench
  • Injectors
  • A laptop
  • A conversion kit
  • A throttle body
  • Sensors
  • An EFI system
  • A wiring harness
  • Machining tools (option: take it to a machine shop)

Remove the Carburetor
Take off the fuel lines and hoses that come from the carburetor. The carburetor is mounted to the manifold by nuts. Use a wrench to remove these and take the carburetor off. If it is in good shape, it's possible to sell it as a used part; if not, then it can go to a junk yard.

Install the Injectors in the Intake Manifold
Injectors need to be installed into the intake manifold. Welding will be involved, so it may be necessary to bring the vehicle or part to a machine shop. Most intakes can be modified using weld in bungs for injectors. Once the injector spot is available, the injectors slide into place and with o-rings for the seal. Injection fuel rails are also necessary, but these need to be machined. Depending on the type of conversion kit, it may come with a ready-to-go manifold that accepts injectors. Many companies also produce ready to go injector manifolds.

Install the Throttle Body
The throttle body regulates the air going into the valves. Universal models are the easiest for conversions. Bolt the throttle body on and hook it up at the throttle linkage. This is connected to the accelerator pedal. An idle air controller is needed with the EFI throttle body. This goes into a small passage that pushes extra air past the throttle plates. It opens or closes the passage depending on how much air is needed in the manifold. Most throttle bodies come with an IAC already installed.

Install the Sensors
In order for the EFI system to monitor and change the injection, several measurements need to be taken. If they're not already in place, several sensors need to be installed. An oxygen sensor, manifold air pressure sensor, air temperature sensor, coolant sensor and throttle position sensor are needed. These are fairly easy to install, as most easily screw into the engine. The kit should contain everything you need. If not, there are sensor packages available.

Adjust the Distributer
Because the new EFI system controls the timing and advance of the ignition, these will need to be locked out of the distributor. The vacuum and mechanical advance also need to be locked out. Most distributors will be fine with a bank-to-bank EFI system. If sequential fuel injection is used, then a dual sync distributor maybe needed.

Set up the Electronics
The electronics are of main importance in an EFI system. The easiest way to install one is to get an aftermarket system, because it's very difficult to reprogram a factory control unit. All of the necessary components are programmed in and by connecting the computer to a laptop you can customize the different settings. Most of the systems will simply need to be mounted and plugged in using a wiring harness. Once you have tuned everything to the desired performance, the vehicle is all ready to go.

Related Questions and Answers

What is the Average Price of a New Fuel Injection Pressure Regulator?

If you have to replace the old fuel injection regulator, read the following. First find out the exact make and model of the car that you are repairing. It will mention the exact kind and variety of fuel pressure injection system that is used. Then you can check with online spare part websites to find the right part. For example, Bosch offers several different varieties and they are priced anywhere from $79-$200 depending on the kind of car and model. Stick to the brand that is mentioned in the owners manual to get the perfect fit and performance.

How Much Money will I Save if I Replace a Fuel Injection Pressure Regulator by Myself?

You can replace a fuel injection if it becomes faulty. The process is simple and there are many video tutorials present online that you can take a look at to learn the process. Make sure that you also read the Owners manual of your car to find the right spare parts. Usually a replacement Fuel Injection Pressure Regulator will cost about $40-$200 depending on your car model. Installing it at a professional garage will cost about $50-$100. Just by installing it yourself, you have saved yourself about $200. Just ensure that you have the relevant technical expertise to work with cars before proceeding.

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