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Mitsubishi Evo X Fuel Injector Installation

Erik Blume  September 18 2019

Tools required

  • Socket wrench
  • 10mm socket
  • 12mm socket
  • Socket extension
  • Torque wrench
  • Pliers
  • Flat head screwdriver
  • Small screwdriver or pick
  • sil glyde or vaseline
  • Penetrating oil (PB Blaster, WD40, etc.)

Installing aftermarket Evo X injectors is a simple task but can be quite nerve-racking if you've never done it before. Thankfully, we've got an awesome technical article to help you through the process.

You'll be able to complete this task with basic mechanical tools, though some additional specialized tools will make the process much easier. Feel free to contact us with any questions you have or any problems you run into during the job!

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Step 1- Relieve fuel pressure from system

  • Open the in-car fuse panel located above the hood release lever, below the steering wheel.
  • Locate the connector with the single blue wire, and unplug the connector (Fuel pump, circled in red).
  • Start the car. It will stall out.
  • Crank the car for a few seconds to be sure there is no pressure left in the fuel system.

Step 2- Remove the fuel rail

  • Start by removing the upper intercooler piping and disconnecting the top half of the wiring harness. Tuck harness out of the way like shown.
  • Disconnect the PCV hose form the valve cover(left image), remove the fuel pressure regulator hose from the return hard line (circled in yellow), and remove the vacuum line from the fuel pressure regulator (circled in red)
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  • Unbolt the fuel return hard line at the 5 points circled. Use a 10mm socket and wrench to remove the 4 screws and 1 nut.
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  • Move the fuel return hard line out of the way.
  • Release the fuel rail feed line by popping the red clip to the right using a flat head screwdriver. (Do not remove the clip from the coupling).
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  • Remove the 2 fuel rail bolts using a 12mm socket and wrench.
  • Pull the fuel rail out. You want to pull the injectors straight out of the intake manifold.
NOTE: Be sure not to drop or lose the 2 black plastic fuel rail spacers (circled)
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Step 3- Replacing the fuel injectors

Note: There is still gasoline in the fuel rail, you can let it slowly drip out of the feed line, or remove one injector carefully, and then the fuel will pour right out.  
  • First remove the retaining clip from each injector by prying them gently with a screwdriver. You do not want to bend the clips. (Clips circled)
  • Pull each injector out of the fuel rail. It may help to use some penetrating oil in the o-ring area. Note: If the o-ring stays in the fuel rail when the injector is removed, make sure to remove it with a small screwdriver or pick. Be sure not to scratch the fuel rail.
  • Apply Sil Glide or Vaseline to the top o-ring of each injector. Insert the injector into the rail with a light twisting motion. The electrical connector will be on the opposite side as the rail mounting tabs as shown. Be careful not to tear or damage the o-rings.
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  • Place the retaining clips back onto the injectors. Be sure that the clip is fully seated, and the fuel rail is locked to the injector
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Step 4- Reinstall the fuel rail

This is done in reverse order of the fuel rail removal with a few important notes.
  • Use Sil Glide or Vaseline to lubricate the injector lower o-rings, then align the injectors with the ports in the intake manifold and press the injectors and rail into place. (Make sure the plastic fuel rail spacers are in place)
  • Reconnect the fuel inlet line to the fuel rail, and lock the connector in place. Install the 2 fuel rail bolts and tighten to 107 in-lbs (12 Nm)
Note: Apply Sil Glide or Vaseline to the fuel rail inlet nipple before installing fuel line connector
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  • Re-attach the fuel return hard line and tighten fasteners to specified torque (4 screws, 1 nut). Red to 49 in-lb (5.5Nm), green to 75 in-lb (8.5 Nm), and orange to 98 in-lb (11 Nm)
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  • Reconnect the upper half of the wiring harness to all connectors. If using plug-and-play adapters for the injectors, connect them in line with the stock injector connectors. (as shown)
  • If you are using solder-in connectors, you will need to cut off the stock connectors and solder the new connectors in their place. (not shown)
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  • Reconnect the fuel pressure regulator return hose, fuel pressure regulator vacuum line, and PCV hose.
  • Reinstall your upper intercooler pipe, and you are done under the hood!
  • Reconnect the fuel pump connector on the inside fuse panel and the install is complete.

Installation of new Evo X injectors requires a retune. Do not try to start the car or drive on new injectors if the car has not been tuned for them.

  • Once you have the proper tune installed, start the car and check for fuel leaks.

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