How to Change an Electronic Fuel Injector

Fuel injection systems come in many configurations. This 4 cylinder 1999 Saab engine has its fuel injectors connected through four independent yellow fuel hoses.

It is one of the most common systems installed on gasoline operated vehicles. Similar to a carburetor, a fuel injection system has to provide the right amount of gas-air mixture, but instead of using engine vacuum, injectors operate through pressure and electrical current. This makes the injection system more efficient. However, their electrical operated coils sometimes open or short out, making the injector useless. Following these simple steps, you can change one, two or all of the injectors to restore the electronic fuel injection system in your vehicle in minutes.

Things You'll Need

• Small screwdriver
• Ratchet and socket set
• Wrench set

Instructions

1. Open the hood of your vehicle.

2. Relieve the fuel pressure system by using a small screwdriver to push the inside stem of the pressure (test) Schrader valve located on the fuel manifold rail-read the Tip section at the bottom for more information.

3. Disconnect the cable from the negative terminal of the battery.

4. Disconnect the fuel hose from the fuel manifold rail-on some vehicle models you might have to remove the upper manifold from the lower manifold for access to the fuel manifold rail.

5. Unplug the fuel injectors’ electrical connector and remove the return fuel hose if necessary for access to the fuel injectors.

6. Remove the bolts or studs that hold the fuel manifold rail in place using a ratchet and socket or wrench-some models provide access to individual injectors by removing a single holding bolt. Look carefully at your system configuration.

7. Lift the fuel rail and injectors assembly. You might have to carefully move the assembly from side to side to lift the injectors out of their lower manifold bores.

8. Remove the failed injector out of the rail by hand using a twisting motion and being careful not to damage any injector assembly components.

9. Apply a light coat of engine oil to the new o-rings and, if necessary, replace the boot and seals; carefully mount the new fuel injector in place using a twisting motion.

10. Install the fuel manifold rail making sure all the injectors are properly mounted on the lower intake manifold and install the bolts or studs.

11. Plug the fuel injectors’ electrical connector; reconnect the fuel hoses, upper manifold and negative cable to the battery terminal.

Tips & Warnings

• Consult your car service manual for the proper procedure to relieve fuel system pressure and locate parts and components on your particular vehicle. You can buy a service manual at most auto parts stores or consult one for free at a public library.

• When working in your car fuel system, make sure you are in a well ventilated area, away from appliances with open flames like dryers or water heaters and do not allow smoking near your vehicle.