Replacing The Fuel Pressure Regulator In A 964 Porsche

Replacing the fuel pressure regulator in a 1991 C2 964 is a complex task that requires careful attention to multiple components. The fuel pressure regulator is located at the back of the engine compartment, and accessing it involves removing some or all of the intake manifold. It is attached to a bracket at the bottom of the throttle body, and special tools such as flare nut wrenches may be required for its removal. Before beginning the replacement process, it is recommended to consult repair manuals or seek advice from experienced individuals to ensure a proper understanding of the procedure.

Removing the fuel pump fuse while the engine is running

To replace the fuel pressure regulator on a 1991 C2 964, you'll first want to relieve the pressure in the fuel system. With the engine running, remove the fuel pump fuse (not the DME relay). The engine will die shortly, and the remaining fuel will be under much less pressure, which will be helpful when you break the lines open.

Next, you'll need to locate the fuel pressure regulator. It is at the end of the engine in the far back of the engine compartment. You will need to remove some or all of the intake manifold. You will want to have a set of flare nut wrenches.

The FPR is attached to a bracket at the bottom of the throttle body. Disconnect the return line so that you can get the closed end of the wrench on the 24mm nut that attaches it to the bracket, rather than the open end. Undo the fuel lines and the centre nut, and the FPR will come out.

When you're ready to install the new FPR, simply follow these steps in reverse. Be sure to use new gaskets or O-rings to seal the intake to the engine.

Removing the intake manifold

To remove the intake manifold of a 1991 Porsche 964 C2, you will need to set aside a long day or two, as it is a complex process. Here is a step-by-step guide:

Firstly, gather your tools and materials. You will need a flathead screwdriver, a 10mm wrench, a punch, a 6mm Allen, and a 5mm Allen. It is also recommended to have a parts drawing or diagram from the parts catalogue to refer to during the process. This will help you identify all the screws and parts that need to be removed. Ensure you have a replacement intake manifold and the necessary gaskets ready.

Next, begin the removal process:

• Remove the fuel rail and injectors.
• Remove the two screws and the air intake to the airbox using the flathead screwdriver. This will give you access to the intercooler to throttle body tube. You may also need to remove the entire airbox, depending on the systems you plan to work on.
• Remove the clamp on the tube to the intercooler using the flathead screwdriver. Completely remove the tube by disconnecting the two hoses connected to it.
• Disconnect the throttle switch connection from the switch mounted on the throttle. The switch will remain mounted to the throttle body. Also, disconnect the vacuum hose from the bottom of the throttle body.
• Using the 10mm wrench, remove the two bolts holding the throttle cable to the intake manifold.
• Remove the 10mm bolt holding the dipstick tube to the manifold.
• Use the punch to gently tap the Allen head bolts. Clean the bolt heads, then ensure that the 5mm Allen socket is properly seated. Remove the two bolts at the rear of the manifold by the oil filler tube.
• Depending on your manifold, there may be several vacuum lines and hoses attached. Use the flathead screwdriver to remove them.
• With a 13mm socket, remove the banjo bolt for the vacuum lines between the three and four intake runners.
• Using a 6mm Allen, remove the eight Allen head bolts on the manifold.
• If the manifold is stuck, gently tap it with a rubber mallet to loosen it. Remove the manifold from the motor, ensuring you also remove the old gaskets and clean the mounting surfaces.
• Immediately cover the intake ports with rags and tape to prevent anything from falling into them, as they lead directly to the combustion chamber.

The removal process is now complete, and you can proceed to replace the fuel pressure regulator and perform any other necessary maintenance. Reinstallation of the new intake manifold is the reverse of the removal process. Take your time and carefully follow each step in reverse order, ensuring all connections and fittings are secure.

Disconnecting the return line

The fuel pressure regulator is located at the end of the engine, in the far back of the engine compartment. To access it, you will need to remove some or all of the intake manifold. It is attached to a bracket at the bottom of the throttle body, and disconnecting the return line will make it easier to remove the 24mm nut that secures it.

Before beginning any work, it is important to take safety precautions when dealing with the fuel system. Make sure to have a fire extinguisher nearby and disconnect the battery to disable the power going to the fuel pump. It is also recommended to wear protective gear, such as fuel-resistant gloves and safety glasses.

To disconnect the return line, first locate the fuel pressure regulator and identify the return line. The return line is the hose that carries the excess fuel back to the fuel tank. Once you have identified the return line, use a fuel hose quick disconnect tool to safely detach it from the regulator. Be prepared to catch any residual fuel that may spill out with a drip pan and a towel.

It is important to work carefully and avoid damaging the return line or any other components in the engine bay. If the return line is cracked or damaged, it should be replaced to prevent fuel leaks.

After disconnecting the return line, you will have better access to the 24mm nut that secures the fuel pressure regulator to the bracket. Use a flare nut wrench to remove this nut and set it aside. With the nut removed, you can now carefully lift the fuel pressure regulator out of its bracket.

Remember to work slowly and deliberately, taking care not to drop any tools or parts into the engine compartment. Once the fuel pressure regulator is removed, you can proceed to install the new one, following the manufacturer's instructions and torque specifications.

By following these steps, you will be able to successfully disconnect the return line and replace the fuel pressure regulator on your 1991 C2 964.

Removing the throttle body

To remove the throttle body of a 1991 C2 964, follow these steps:

Firstly, disconnect the cable from the negative terminal of the battery. It is important to wait for approximately 20 seconds or longer after turning the ignition switch to the "LOCK" position before proceeding. This step is crucial for safety reasons and to avoid any potential electrical hazards.

Next, remove the left-hand engine hood side panel to access the engine compartment. After that, you will need to drain the engine coolant. Refer to the appropriate maintenance manual or a trusted online source for detailed instructions on how to drain the coolant safely and properly.

Once the coolant is drained, disconnect the throttle cable from the throttle linkage. This will involve detaching the cable from the throttle body or carburettor, depending on your vehicle's specific setup. Then, disconnect the accelerator cable from the throttle linkage as well. This step may vary depending on the vehicle, but it typically involves releasing a clip or clamp that secures the cable to the throttle linkage.

Now, remove the air cleaner or air filter assembly. This step may vary depending on your vehicle, but it typically involves unscrewing or unclipping the air cleaner housing and carefully lifting it out. Make sure to note the orientation and positioning of any hoses, tubes, or sensors connected to the air cleaner for proper reassembly.

At this point, you will need to disconnect various sensors and valves connected to the throttle body. This includes the throttle position sensor connector and the idle speed control (ISC) valve connector. Carefully detach the connectors by gently pulling them away from the throttle body.

Additionally, there are several hoses that need to be disconnected from the throttle body:

• Two vacuum hoses from the EGR vacuum modulator.
• Vacuum hose from the EVAP VSV (Evaporative Emission Control System Vacuum Switching Valve).
• Water bypass hose from the water outlet.
• Water bypass hose from the water bypass pipe.
• Air hose from the A/C VSV (Air Conditioning Vacuum Switching Valve).

After disconnecting all the necessary components, you are now ready to remove the throttle body itself. Locate and remove the bolts securing the throttle body in place. The number of bolts may vary depending on your vehicle, but make sure to keep them organised and safe for reassembly. Once the bolts are removed, carefully lift out the throttle body, being mindful of any remaining attached hoses or connectors.

If necessary, you can also remove the ISC valve from the throttle body. This step may be required if you are replacing the ISC valve or performing further maintenance on the throttle body assembly.

Removing the fuel lines

To remove the fuel lines of your 1991 C2 964, you will first need to locate the fuel pressure regulator. It is at the end of the engine in the far back of the engine compartment. You will need to remove some or all of the intake manifold to access it.

Before you begin, make sure you have a set of flare nut wrenches. It is also important to protect your hands by wearing fuel-resistant gloves. You should also keep a fire extinguisher nearby.

To remove the fuel lines, start by disconnecting the return line. This will give you better access to the 24mm nut that attaches the fuel pressure regulator to the bracket. Use the appropriate wrench to loosen and remove this nut.

Next, undo the three fuel lines that connect to the fuel pressure regulator. These can be tight, so you may need to use some force, but be careful not to damage the surrounding components. Once the fuel lines are undone, the regulator should come out with the throttle body.

If your fuel lines are very hard or show signs of damage, such as bulging or cracking, it is recommended to replace them. You can purchase new fuel lines from specialised retailers.

Frequently asked questions