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Fuel Injector Swap

While it may be theoretically possible to do this without removing the upper half of the intake manifold, you can't really see what you're doing unless the top half of the manifold is off. So, in order to be able to see what you're doing, the first step is to remove the intercooler and throttle body, and then remove the upper half of the intake manifold. This is complicated by a stamped piece of sheet metal that holds part of the fuel system in place. This piece of metal holds the two halves of the intake manifold together, and is attached to the lower half by the same bolt that holds the oil dipstick in place. The bolt goes into the lower intake manifold from the upper back side and is somewhat difficult to remove. Once it's out, the metal piece can be pried off of the manifold joint and the removal of the upper half of the intake manifold is simply a matter of unbolting it from the lower half.

Now that the upper half of the intake manifold is off, the entire fuel rail is easily accessible from directly above. There are two small bolts holding it to the lower intake, one from above and one from the front near the alternator and distributor. Once these are removed, you can pull upward on the fuel rail and the injectors should slide out of the lower intake manifold. Some force may be required if they are really crusted in. With the fuel rail out, you can now remove the injectors from the rail. You may need to spray the connection of each injector to the fuel rail with carburetor cleaner several times before they will come out. Over time, deposits in the fuel seem to make the injector O-rings stick very hard in the rail. With enough carburetor cleaner and time, they will come out, though. You also need to remove the electrical connector from each injector to complete its removal. The connector has wire in it that catches on lugs molded into the injector. The wire is not a complete loop, though, and can be easily pried away from the lugs using something like a small screwdriver. When both lugs are free, the injector should slide out of the eletrical connector.

If you're not using new injectors, you'll want to at least change the O-rings on the injectors that you're installing. Each pintle cap will probably break when you remove it to replace each lower O-ring, so what you want are kits that are available from NAPA and some other parts stores that include two O-rings and a new pintle cap. Then it's a simple matter of removing the old pintle caps and O-rings and installing the new ones on each injector. Then lube up the new O-rings with a little grease or Vaseline and install them back into the fuel rail. Attach the electrical connectors and install the rail into the lower intake manifold. Put the upper intake back on, and secure the metal piece and dipstick tube with the bolt that goes in from the back again. All that's left is the throttle body and intercooler and you're all set.

If you've installed bigger injectors than before, you will need to install a computer calibrated for the larger injectors if you have not already. The factory computers seem to be able to adapt to injectors approximately 10% oversized, such as putting 38lb/hr injectors on a car with a computer calibrated for 35lb/hr injectors. They do not seem to be able to deal well with larger jumps such as running 35lb/hr injectors on an old SVO computer designed for 30lb/hr injectors, or running 42s on a 35 box. They WILL run, but tend to load up with fuel at Wide Open Throttle (WOT).


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Page last updated: Friday, 28-Oct-2005 11:26:05 EDT