How to Free Stuck Fuel Injectorsby Richard Rowe
It's one of the more frustrating parts of DIY car maintenance; spending two hours doing the hard part, getting to the easy part and finding out that something's conspired to make it not-so-easy. Finding out that your injectors are stuck in the fuel rail or manifold can be a real facepalm moment -- which, in itself, can prove far more painful than the process of breaking the injector loose.
Check around the injector for any metal clips or screw-on retainers that might be holding it in place. Almost all fuel injectors use something to secure the injector to the rail and those metal clips can camouflage themselves pretty effectively on the underside of the rail. Carefully pull the clips loose with a set of needle-nose locking pliers. Use an impact screwdriver to break a sticking retaining screw, if needed.. Set the driver on its lowest setting to avoid stripping the screw head.
Twist the injector by hand. Very rarely will you find a standard fuel injector keyed to the manifold or rail. Almost without exception, fuel injectors use round mounts and O-rings to seal to the rail/manifold. So, once you have any retainers free, the fuel injector should turn freely in its mounting hole. If it turns at all, which it likely will, then it will come out if you work it correctly. If not, you'll need some chemical assistance.
Spray the area around the fuel injector mating area -- where it connects to the rail or manifold -- with a liberal amount of penetrating oil and allow it to sit for ten minutes or so. If you have injectors that plug into the top of the rail and pass through, then spray around the bottom of the injector as will. Injectors generally stick because the rubber sealing ring dries out and sticks to the rail and injector. The purpose here is to both lubricate the outside of the ring and thoroughly saturate the ring to soften it.
Turn the injector clockwise and counterclockwise, if possible, to disperse the lubricant. If the injector wont turn, then wiggle it in a circular, oscillating motion to cause the O-ring to "breathe" the lubricant in and out. Take your time here, and don't be shy with additional lubricant. Keep going until the injector rotates in the housing. Turn the injector so that its harness plug runs parallel to, and directly over, the fuel rail.
Slide a large flat-head screwdriver between the fuel rail and the injector plug. Push in and twist the screwdriver. You probably won't have clearance to properly lever the injector up and, even if you could, you'd end up doing it too quickly. As you twist the screwdriver to open up a slight gap, spray the area again with lubricant. Slowly lift the injector and set it back down to distribute the lubricant and break any vacuum that may be present between the injector and the fuel rail.
Pull up and twist the injector out. Think of the injector like the cork in a wine bottle; you can expect it to fight back a bit. You can use a set of channel-lock pliers to get the injector out, but be very, very careful not to squeeze down or snap the top of the injector off. Take your time -- as long as the injector turns, it will come out eventually.