Fuel Injector and Fuel Rail Removal and Installation

Overview

This procedure outlines how to remove and install the fuel injectors and fuel rail on a Porsche 944 S / S2 with a 16v engine. It’s essential for replacing faulty injectors, servicing the fuel system, or performing maintenance to ensure proper engine performance.

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Tools Required

• 10mm (3/8 inch) socket, ratchet, and 6-inch (152mm) extension
• Flat tip screwdriver
• Thin head 24mm (15/16 inch) open end wrench
• 19mm open end wrench
• Small flat tip screwdriver or probe
• Catch rags

Parts Required

• Fuel injector O-ring seals (if worn) – 944 110 901 00
• Fuel injector caps (hats) (if damaged) – 944 606 115 00

Step-by-Step Procedure

1. Prepare the Vehicle

1. Disconnect the negative lead from the battery to ensure safety while working on the fuel system.

2. Disconnect Fuel Lines

2. Place catch rags under the fuel pressure damper (front of the fuel rail) and fuel pressure regulator (rear of the fuel rail) to catch any fuel spills.
3. Use a thin head 24mm (15/16 inch) wrench to hold the fuel pressure damper retaining nut, then disconnect the fuel supply line using a 19mm wrench.
4. Loosen the retaining clamp on the fuel return line with a flat tip screwdriver and disconnect it from the fuel pressure regulator.

3. Disconnect Vacuum Lines and Wiring

5. Disconnect the vacuum lines from the fuel pressure damper and fuel pressure regulator.
6. Remove the plastic cover from the fuel rail by lifting it off carefully.
7. Using a small flat tip screwdriver or probe, gently disengage the wire clips on the fuel injector electrical connectors, then disconnect the plugs and move the wiring harness aside.

4. Remove the Fuel Rail

8. Using a 10mm (3/8 inch) socket with a 6-inch (152mm) extension, remove the four fuel rail retaining bolts. Note that the two bolts nearest the intake manifold may be hard to see due to their position under the damper and regulator.
9. Disconnect the spark plug wire retaining clips from the fuel rail. If the spark plug wires for cylinders #3 and #4 interfere, disconnect and remove them as needed.
10. Grasp the fuel rail firmly and pull it upward to separate it from the intake manifold. The fuel injectors will come out with the rail.

5. Remove Fuel Injectors (If Needed)

11. Observe how the retaining clips hold the fuel injectors in the fuel rail before removing them.
12. Remove the retaining clips and pull the fuel injectors out of the fuel rail.
13. Inspect the injector O-ring seals (944 110 901 00) and caps (944 606 115 00) for wear or damage. Replace if necessary.

6. Install Fuel Injectors (If Removed)

14. Secure the fuel injectors into the fuel rail with their retaining clips, ensuring they are properly seated as observed during removal.

7. Install the Fuel Rail

15. Ensure all fuel injectors are correctly attached to the fuel rail with their clips.
16. Lower the fuel rail onto the intake manifold, ensuring the injectors align with and insert into their holes.
17. Tighten the four fuel rail retaining bolts (M6) to 8 Nm (6 ft-lbs) using a 10mm (3/8 inch) socket.
18. Route the spark plug wires as you install the fuel rail, reconnecting any removed wires for cylinders #3 and #4.
19. Position the fuel injector wiring harness along the top of the fuel rail and reconnect the electrical plugs to the injectors.
20. Reinstall the plastic fuel rail cover.

8. Reconnect Fuel and Vacuum Lines

21. Reconnect the fuel supply line to the fuel pressure damper using a 19mm wrench while holding the damper nut with a 24mm (15/16 inch) wrench.
22. Reconnect the fuel return line to the fuel pressure regulator and tighten the retaining clamp with a flat tip screwdriver.
23. Reattach the vacuum lines to the fuel pressure damper and fuel pressure regulator.

9. Finalize Installation

24. Reconnect the battery negative lead.
25. Turn the ignition on to pressurize the fuel system.

Post Procedure Checklist

• Check for fuel leaks around the fuel supply line, return line, and injectors.
• Ensure the fuel rail is securely fastened and doesn’t move.
• Verify all electrical connectors and vacuum lines are properly attached.
• Start the engine and listen for irregular noises or performance issues.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manual, Volume 1
• Youtube