Jeep Cherokee Fuel Injectors

How to change an injector or fix a leaking O ring

Begin by obtaining the proper sized O rings. These are available from your local Jeep dealer or from a Crown Distributor like me. It is important that you get the proper sized O rings as you don’t want fuel leaking down on the hot manifold.

You only need a few simple hand tools to replace an injector or change the O rings. On the 90 and earlier Cherokees, the fuel rail is held in place by four bolts with 13 MM heads. You will need a pick to remove the old O rings. I found a magnet handy for getting the bolts out once they were loosened.

Also, since you are going to be spilling fuel on a potentially hot manifold, be sure to have a big fire extinguisher on hand just in case.

Even if you are just replacing one injector, you have to remove the entire fuel rail. On this 1989 Cherokee, the rail is held in place by four bolts.

After the bolts are loose, I used a magnet to fish them out of the brackets.

With all the bolts loose, pull the fuel rail away from the manifold. This will pull the injectors out of the manifold. To service an injector, first remove the electrical connector. I use a pick to gently pry the clip back so it will pass the detente on the injector. Be careful not to loose the clip as they are expensive to replace.

Next remove the clip that holds the injector to the fuel rail. It just slides off. I use the pick again to help get it moving. Don’t loose these either as they are not available form Jeep separate from the fuel rail.

One it is unclipped, pull the injector out of the fuel rail. Sometimes it helps to twist it, to get it out.

I used the pick to pull the old O rings off the injector. Note: on the Jeep, the brown O ring goes on the manifold end and the black O ring goes on the Fuel rail end.

Insert the injector back into the fuel rail. I found it helpful to put a drop of oil on the O rings to get them back into the fuel rail. Again twisting it helps to get it in. Reinstall the clip that holds the injector to the rail. Make sure the slots are properly aligned. If they are not, you may not have the injector seated properly. The clip will slide on easily when the injector is properly seated.

Twist the injector to the proper position and reconnect the wire. Make sure the clip seats with a click in the detente.

Repeat with procedure with the remaining injectors.

One you are ready to reinstall the fuel rail, carefully align the lower part of the injectors with the manifold openings. Use the heel of both hands to press the fuel rail into place and seat the lower part of all the injectors.

One the injectors are seated, replace the bolts that hold the fuel rail in place. Look around for vacuum tubes that have been knocked out of place during the procedure. The MAP sensor line and the vacuum line to the fuel pressure regulator will likely be knocked loose by moving the fuel rail around. reconnect them before starting the engine.

Turn the key to on and listen for the fuel pump to run. Do not start the engine yet. Inspect for leaks first. If you see a leak, loosen the fuel rail and wiggle it around to seat the leaking injector. Again twisting the injector may help.

Once you have a seal, start the engine and check for leaks again. If you see any, shut off the engine immediately and reseat the leaking injector.