Porsche Parts Catalog Porsche Accessories Catalog Porsche Technical Articles Porsche Tech Forums
 
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
Bookmark and Share

Pelican Technical Article:

Fuel Injector Replacement

Steve Vernon

Time:

3 hours3 hrs

Tab:

$1 to $1,800

Talent:

**

Tools:

22mm, 19mm, 17mm wrench, 5mm Allen, flathead screwdriver,

Applicable Models:

Porsche 993 Carrera (1995-98)
Porsche 993 Carrera 4 (1995-98)
Porsche 993 Carrera 4S (1996-98)
Porsche 993 Carrera S (1998)
Porsche 993 Targa (1996-98)
Porsche 993 Turbo (1996-97)

Parts Required:

Injectors, O-rings

Hot Tip:

Use care working with fuel

Performance Gain:

Proper engine performance

Complementary Modification:

Replace fuel filter

If your car is starting to run rough, getting horrible gas mileage or has an error code, there is a good chance it is time to replace the fuel injectors. Modern fuel injectors are made of plastic and we do not recommend having them serviced or rebuilt. Older mechanical injectors were opened by fuel pressure alone and were easier to service; newer injectors are made of plastic, need an electronic pulse from the ECU to open and are better replaced than sending them out for service.

A properly working injector will send a precise amount of atomized fuel into the induction system at a designated time. A weak or improperly working injector can do everything from send no fuel, to leak raw, non-atomized fuel into your engine.

The first step in diagnosis is to go over the basics. Is the fuel pump operating? Is the fuel filter clogged? Is there actually any fuel in the vehicle? Believe it or not, many people overlook these steps. The fuel injectors for the 993s are not cheap, so before you change yours out, make sure they are faulty and check the fuel pressures. Please see our article on fuel pressure testing for additional assistance.

Be prepared: Work in a well ventilated area. Keep a fire extinguisher near you at all times and know how to use it correctly. No sparks or open flame around and if you smoke now would be a really good time to quit: at least for the couple of hours it might take you to perform this job.

Just as with the fuel filter, injectors, or any other component of the fuel system, it's best to relieve the fuel system of any pressure before you go opening it up. You can do this by opening the fuel filler cap and/or removing the fuel pump fuse from the car's fuse panel and then starting the car and allowing it to idle until it runs out of fuel. Also, be sure to use some protective gloves and goggles whenever you're working with fuel.

Some fuel will spill out no matter what you do so be prepared to catch it with some rags and dispose of the rags in accordance with the regulations in your area. Never store fuel soaked rags anywhere; they are very dangerous.

You are going to be opening holes that go into the engine so before you begin get a can of compressed air and blow all the dust and debris away from the injector ports.

Before you begin working on the fuel system you want to de-pressurize it.
Figure 1

Before you begin working on the fuel system you want to de-pressurize it. The best way to do this is to remove the fuel pump and oxygen sensor fuse from the fuse box in the front trunk and then start the engine and let it run out of fuel. Open the front trunk and pull back the carpeting closest to the windshield. The fuse box is on the right side. Remove the cover and check your owner's manual to determine the right fuse. On our 1995 it was fuse number 26. The panel is set up so fuses 1-15 run along the side and fuses 16-41 run along the top. There is a fuse puller and spare fuses in the box (red arrow). Do not remove the DME relay as this will not allow the engine to run and you will not be burning the fuel in the system off. Remove the fuel pump fuse and run the motor until it stalls.

The injectors and fuel rail on the left side of the motor for bank 1-3 are located below the heater blower motor (red arrow) and you will need to remove this to replace the injectors.
Figure 2

The injectors and fuel rail on the left side of the motor for bank 1-3 are located below the heater blower motor (red arrow) and you will need to remove this to replace the injectors. Please see our article on removing your Varioram or non-Varioram heater blower for additional assistance.

With the blower removed you can see the fuel rail (red arrow) and the injectors.
Figure 3

With the blower removed you can see the fuel rail (red arrow) and the injectors.

Use a 22mm wrench to support the fitting on the pressure regulator and a 19mm wrench and separate the fuel line (red arrow) from the regulator.
Figure 4

Use a 22mm wrench to support the fitting on the pressure regulator and a 19mm wrench and separate the fuel line (red arrow) from the regulator. Even though you have run the system dry there will still be fuel that will escape when you separate the line from the rail so be prepared to catch it and dispose of it correctly. Disconnect the vacuum line (yellow arrow) from the top of the regulator.

Squeeze in the clip on the injector electrical connections and pull them straight back and off (red arrow).
Figure 5

Squeeze in the clip on the injector electrical connections and pull them straight back and off (red arrow). Remove the clips and harness from the rail.

The mount on the rear of the rail is partially blocked by a large wiring connection.
Figure 6

The mount on the rear of the rail is partially blocked by a large wiring connection. Remove the connection and separate them (red arrow) to give you more room to work

Use a 5mm Allen and remove the two mounting bolts (red arrows).
Figure 7

Use a 5mm Allen and remove the two mounting bolts (red arrows).

Wiggle and pull the injectors and rail straight up and out from the intake manifold.
Figure 8

Wiggle and pull the injectors and rail straight up and out from the intake manifold.

The injectors are held into the mounts on the rails by a single clip (red arrow).
Figure 9

The injectors are held into the mounts on the rails by a single clip (red arrow). Use a flathead screwdriver and slide the clip off.

You can now pull the injectors out from the rail.
Figure 10

You can now pull the injectors out from the rail. When installing injectors it is a good idea to use a small amount of white Lithium grease on the O-ring when installing it into the rail. Always replace the O-rings (red arrows) every time you remove and reinstall the injectors.

Once you pull the injectors out from the intake manifold you should immediately plug the injector holes with clean shop towels or rags.
Figure 11

Once you pull the injectors out from the intake manifold you should immediately plug the injector holes with clean shop towels or rags. These openings go directly into the head and combustion chamber and you do not want to drop anything down into them.

The injectors and fuel rail on the right side of the motor for bank 4-6 are located below the air box (red arrow) and you will need to remove this to replace the injectors.
Figure 12

The injectors and fuel rail on the right side of the motor for bank 4-6 are located below the air box (red arrow) and you will need to remove this to replace the injectors. Please see our article on removing your Varioram or non-Varioram air box for additional assistance.

You will also need to remove the A/C compressor so please see our article on A/C belt replacement for further information.
Figure 13

You will also need to remove the A/C compressor so please see our article on A/C belt replacement for further information.

On the right side rail use a 17mm wrench to support the rail (yellow arrow) and a 19mm wrench and separate the fuel line (red arrow).
Figure 14

On the right side rail use a 17mm wrench to support the rail (yellow arrow) and a 19mm wrench and separate the fuel line (red arrow).

Disconnect the injector connectors and remove the wiring harness form the rail in the same manner as the left side rail and injectors.
Figure 15

Disconnect the injector connectors and remove the wiring harness form the rail in the same manner as the left side rail and injectors.

Remove the two 5mm Allen bolts from the rail (red arrows) and pull the rail out from the intake.
Figure 16

Remove the two 5mm Allen bolts from the rail (red arrows) and pull the rail out from the intake. The rest of the procedures are the same as for the left side. Installation is the reverse of removal. Expect the car to run a little rough for the first few seconds while the air is removed from the lines.

Bookmark and Share

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Fri 12/9/2016 03:07:11 AM