The Jeep's fuel injectors control the injection of pressurized fuel into the combustion chamber of the engine. Fuel injectors are electronically controlled and spray the fuel in a fine mist to allow the fuel to combine more evenly with the air in the combustion chamber. Fuel injectors are fitted into your Jeep's engine and fuel lines and are secured in place with O-rings. Vibration and decomposition of the O-rings can result in leaks at the high pressure fuel line or from the point of connection to the engine. Pressurized fuel lines will trickle a constant flow of fuel through leaking seals, unless repaired.
Turn the Jeep's ignition key to the "electronics only" mode. The fuel pump will pressurize the fuel system.
Inspect the fuel injectors for leaks. Vibration, corrosion and material decomposition can result in failure of O-rings securing the injector to the fuel rails or engine. If the fuel is leaking at the fuel rail connection, the O-ring should be replaced. If the fuel is leaking inside the engine -- which may be evidenced by the Jeep's on-board computer reporting lean or rich fuel to air ratios for a cylinder -- the injector should be replaced. Both O-ring replacement and injector replacement will require removal of the injector.
Remove the key from the ignition.
Depressurize the fuel system. Disconnect the fuel safety cut-off switch -- which disables the fuel pump -- and start the Jeep to consume the fuel in the lines to reduce the pressure, then disconnect the battery.
If your Jeep is not equipped with a fuel safety cut-off switch, disconnect the battery and remove a fuel line to reduce the pressure on the line. Catch any fuel in a clean cup and return to the tank. Replace the fuel line.
Remove any components required to access the fuel rails or fuel lines connected to the fuel injector. Air intake tubes, vaccuum tubes, electrical plugs and bolt on-devices should be carefully documented to allow replacement when the injector has been serviced.
Disconnect the fuel rail from the engine. Some fuel rails are bolted to the engine to reduce vibration. Remove the bolt and set aside.
Disconnect the electrical plug on the fuel injector. Move the plug away from the injector.
Remove the fuel rail from the top of the injector. Rock the fuel rail back and forth and pull directly away from the injector. The injector is secured in place with an O-ring. Once the fuel rail is removed, inspect the injector to ensure the O-ring is in place. If the O-ring is not on the injector, retrieve the O-ring from the fuel rail connection.
Remove the injector from the engine. Grasp the injector with your hand and pull directly away from the engine. Remove the O-rings from the injector and discard.
Inspect the injector for leaks or damage. If the injector has already been confirmed as damaged, or inspection reveals damage, discard the injector.
Install new O-rings on the injector. The injector nozzle and fuel rail connection point will each have an O-ring installation point. Before installing the new O-rings, coat them with a thin layer of motor oil. The motor oil will lubricate the O-ring during installation to reduce the likelihood of tearing. The lubrication will also assist in the proper seating of the O-ring in the fuel rail or engine. If replacing the injector, the new injector may have O-rings installed. Lubricate the O-rings before installing the injector on the engine.
Press the injector, nozzle end first, into the injector hole on the engine. You may feel a slight popping sensation as the injector O-ring is seated in the fuel injector hole. A correctly seated injector will resist removal from the engine.
Install the fuel rail onto the fuel injector. Press the fuel rail onto the connection point until the injector is full seated into the fuel rail. Correctly seated rails will resist removal.
Replace any engine components removed to gain access to the fuel injector.
Connect the Jeep's battery. Turn the ignition key to electronics only mode and wait 10 seconds to allow the fuel pump to pressurize the system. Inspect the fuel rails and fuel lines for leaks. Start the Jeep to confirm installation.
