I originally read this procedure on the Pelican Parts BBS. I tried the procedure and found it worthwhile, so I felt it would be useful to write it down as a tech article. While I kept the gist of the procedure intact, I added/modified a few of the steps that I felt made the procedure easier.
Thanks to "944Pilot" and "Porschemotorsport" for the procedure.
Warning/Disclaimer: This procedure involves working with your fuel system, as well electrical components in close proximity to your fuel system -there is a chance of seriously injuring/killing yourself or causing serious damage to your car if you screw up - gasoline burns, gasoline vapor explodes, and electricity can shock you, cause sparks, and other assorted unpleasant things - 'nuff said.
- 10mm socket
- Small Flathead screwdriver
- Adjustable wrench
- 2 hose clamping pliers
- Rags for clean up
- A couple of medium sized Baggies and rubber bands
- 4 x Fuel injector seal kits (Pep Boys - Borg-Warner kit #274081, $2.49 each - comes with O-rings, washer, and the "hat")
- 2 cans of carburetor cleaner
- 2 cans of brake cleaner
- New, clean ATF
- 1 short length of hose to fit the injector
- Hose clamp for the same
- Compressed air source
- Battery charger with 2mv setting
- 2 wires, about 12 - 24 inches long
- 1 Push button, momentary, normally open switch. (about $3.00 at radio shack)
- 2 alligator clips
1. Depressurize your fuel system -by pulling the fuel pump fuse and running the engine until it quits.
2. Disconnect the negative from the battery
3. Disconnect and remove your spark plug wires - now is a good time to inspect for damage - replace as necessary
4. Put a baggie over your distributor - secure with rubber bands (Note spilling fuel in your distributor can cause an explosion when you start the car)
5. Clamp the fuel feed and return lines running to the fuel rail
6. Disconnect the vacuum hoses running to the fuel regulators
7. Remove the plastic fuel rail cover (depending on how your wires and hoses are routed, you may have to do this earlier)
8. Disconnect the wiring harness from your fuel injectors, move the wiring harness out of the way
9. Unbolt the fuel rail from the engine
10. Pulling lightly, remove the fuel rail/injector assembly from the car, you can flip it upside down and rest it on the shock tower.
11. Using your drip pan and the adjustable wrench, loosen the large bolt on the front of the fuel rail and drain the fuel from the rail (NOTE: if you have to remove the bolt, DO NOT lose the sealing ball inside the bolt)
12. Pry the retaining clips off of the injectors
13. Grasp the injector and pull it out of the fuel rail - you may have to wiggle it a bit to work it loose - keep your injectors in order - make sure that injector #1 goes back in cylinder #1 (this isn't a requirement, but it seems like a good idea to me)Cleaning Procedure:Now that the injectors are off, take a moment to clean the injector mounting points on the fuel rail with carb cleaner and a Q-tip. Do the same for the injector ports on the engine and the fuel injector wiring harness terminals
1. Spray the injector with brake cleaner to remove dirt, grime etc.
2. Work the little plastic "hat" off of the injector tip (Warning!: Don't damage the actual injector tip)
3. Slide the O-ring and plastic washer off of the injector
4. With the small screwdriver, work the top O-ring off (Where the injector connects to the fuel rail)
5. Spray it down with brake cleaner again, use a lint free towel to wipe the O-ring surfaces down
6. Fill the injector with carb cleaner, prop it up (not resting on the tip!!!) and let the cleaner drain through it - you can remove the O-rings, hats, and the like from the others while it is draining.
7. Attach the hose to the injector tip, again, being extremely careful not to damage it, secure with the hose clamp.
8. Now it is time to backflush the injector - to get the injector to open up, you must apply voltage to the injector. This is done with the battery charger. The trick is, you must "Pulse" the voltage, DO NOT apply constant voltage to the injector. You can do this by turning the charger on and off repeatedly, or, you can wire a simple circuit to make this much easier:
A. Take 1 wire, attach an alligator clip to one end, strip the other end.
B. Take the other wire, cut it in half, strip all ends, attach an alligator clip to one end, then wire the switch to the pieces of wire, making one wire again.
C. Connect the alligator clips to the injector terminals, the bare ends of the wire to the battery charger wires.
9. Fill the hose with carb cleaner,.
10. Turn on the battery charger, apply a compressed air source to the end of the hose. If you rigged up the switch assembly listed above, there will not be any power going to the injector until you push the button, if you didn't, you have to turn the charger on/off every couple of seconds, with the switch, just repeatedly push the button.
11. After the hose is empty, do it again.
12. Now flush the injector the other way twice.
13. Spray the injector down again with brake cleaner.
14. Time to reassemble the injector. Holding it tip up, slide the washer, O-ring, and then the hat from the kit. Flip the injector over and install the other O-ring.
15. Lube the O-rings with clean ATF, reinstall on fuel rail.
16. Repeat for the other 3 injectors
17. Fuel rail installation is the reverse of removal.
18. After installation, put the key in the ignition and turn the key to "ON" for a few moments to build fuel pressure back up.
19. Start the car.
This procedure took me about 60 minutes to accomplish. Since it was done, I've noticed the engine runs a little smoother, and the acceleration is a little quicker.
Michael Van Bibber (AFJuvat)