Before you begin the process of replacing a fuel injector or fuel injection rail, you need to think about safety. Always keep fire safety in mind when you are working with fuel. You also need to be sure you are wearing eye protection. Even if you've released the pressure in the fuel injection system, there could be some fuel flying when you start disconnecting high pressure lines and removing injectors.
Be sure to follow the procedure for relieving the fuel system pressure.Very important!
Look over your car's injection system. Some systems are easily accessible and others are practically buried. Plan your attack so your job can be organized
It's a good idea to get a fuel injector puller if you are removing fuel injectors. There are other ways to do it, but you risk damaging expensive fuel injection components.
Disconnecting the Fuel Rail
If your fuel injection system has a fuel rail to deliver fuel to the fuel injectors, you will ahve to remove this before you are able to remove the injectors. This is an easy job.
First, disconnect the main fuel line at the end of the rail. There may be an additional line at the other end, so remove that one, too. The fuel rail is help in place by screws or bolts, depending on your car's setup. Remove these screws or bolts.
If your wiring travels over the top of the rail, see the next step to disconnect the wiring first. With everything disconnected from the rail, pull it away from the fuel injectors. Most fuel rails are just pressed onto the injector tops, once you've removed the hold down screws or bolts it should pull away, with a little oomph.
Most fuel injector wiring plugs are held securely in place by a springy wire (see pic). To remove this wire, just insert a flat head screwdriver in the space between the spring and the plug and pry it carefully away. It will come out easily. Don't lose it!
If your car uses a fuel rail to deliver fuel to the injectors, you removed it in the previous step. If you don't have a fuel rail, you'll need to remove a fuel line from the top of each injector. It's just as easy to remove, just do it carefully.
With the fuel delivery out of the way, you're ready to disconnect the fuel injectors. Each injector will have a plug at the top (or on the side near the top) that connects to the wiring harness.
Pulling the Fuel Injector
With all of the other stuff out of the way, you're ready to yank the injector. Unfortunately, many people really do try to yank them out. Remember, your fuel injectors sit right in the middle of the delicate are of the engine, so any piece you break off might fall in, and this equals big pain in your fanny.
The safest way to remove a fuel injector is to use a fuel injector puller. There are other ways to remove fuel injectors, but if you aren't careful you could damage some expensive fuel injection components.
Besides, the injector puller makes it so easy, just slide it underneath the lip in the injector housing and pop the injector out.
Your fuel injector goes into what amounts to a hole in the intake manifold (or your head if you're lucky). When you remove the injector, you leave this hole open. Be very careful to keep anything from falling in. This can be a real chore to fix.
In the immortal words of every auto repair tutorial, installation is the reverse of removal! You'll need to lubricate the new injector seals before they go in, and remember to go easy, don't force anything in.