Replacing Your Duramax Fuel Pressure Regulator: Step-By-Step Guide

If you're experiencing a surge at idle every few seconds, it may be time to replace your fuel pressure regulator. This is a labor-intensive but rewarding DIY project that can save you a lot of money compared to taking your vehicle to a mechanic. The process involves removing and disconnecting various parts of your engine, such as the air intake pipe, A/C compressor, drive belt, water outlet tube, electrical connectors, and fuel lines, before finally removing and replacing the fuel pressure regulator itself. It is important to clean and dry the area thoroughly and to be careful not to damage any O-rings during the process.

Disconnect the negative feed from the batteries

Disconnecting the negative feed from the batteries is an important first step when replacing the fuel pressure regulator on a Duramax engine. This is because forgetting to do so could be dangerous, as one person who has performed this procedure notes.

To disconnect the negative feed from the batteries, you will need to have a 1/4" breaker bar to hand. You should use this to remove the belt from the pulleys. Place the head of the bar into the square socket on the belt tensioner, then push on it towards the passenger side. With your right hand, you can then lift it off the AC Compressor unit.

This step should take place as part of the preparation stage of the replacement process. Before beginning work, it is also important to gather all the necessary tools and materials. For this job, you will need an LBZ FPR, new oil, anti-freeze, and a range of tools including various wrenches, screwdrivers, sockets, and a magnet wand.

Remove the belt from the pulleys

To remove the belt from the pulleys, you will need a 1/2" breaker bar. Place the head of the bar into the square socket on the belt tensioner. Push on it towards the passenger side and then lift the belt off the AC Compressor unit with your right hand.

You can also use a 1/2" breaker bar to remove the belt from the pulleys. This tool is designed to remove tension from the belt, allowing you to slip it off the pulleys. Place the head of the bar into the square socket on the belt tensioner, which is located on the passenger side of the engine. Push the breaker bar towards the passenger side of the vehicle, then lift the belt off the AC compressor unit with your free hand.

It is important to relieve the tension on the belt before removing it from the pulleys. This can be done by pushing the breaker bar towards the passenger side of the vehicle, as mentioned above. Alternatively, you can use a belt tensioner tool to relieve the tension. Place the tensioner tool on the belt tensioner and squeeze the handle to release the tension. Once the belt is loose, you can remove it from the pulleys by hand.

When removing the belt, be careful not to let it fall into the engine compartment. It is a good idea to have a rag or piece of cardboard handy to catch the belt if it slips. Once the belt is removed, set it aside in a safe place where it will not be damaged or contaminated.

Disconnect the two connectors on the AC unit

To disconnect the two connectors on the AC unit of your Duramax, follow these steps:

First, make sure you have gathered all the necessary tools and materials, including a 15mm socket. It is also important to note that this process will involve working with fuel lines and electrical connectors, so proceed with caution and ensure a safe work environment.

Now, locate the AC unit and the two connectors you need to disconnect. They should be clearly marked, as shown in the picture referenced in the source. Once you have identified the connectors, use the 15mm socket to loosen and remove the four bolts that secure the AC unit to the engine. These bolts should be marked with white circles and arrows in the image.

After removing the bolts, carefully move the AC unit out of the way by flipping it towards the passenger side battery. This will give you better access to the connectors. Now, you can proceed to safely disconnect the two connectors. Ensure that you are only disconnecting the connectors associated with the AC unit and be cautious not to interfere with any other components.

Once the connectors are disconnected, set the AC unit aside and continue with the next steps in the fuel pressure regulator replacement procedure. Remember to work carefully and consult a professional mechanic or a detailed guide if you are unsure about any steps in the process.

Remove the coolant stack

To remove the coolant stack, you will need to perform the following steps:

Firstly, using a sharp object, open the clip that holds the wire harness together. This will allow you to split the wire group up. Next, remove the red bolt from the thermostat housing and set the bracket aside. Then, remove the two bolts that hold the metal piping to the engine. Following this, remove the four bolts using a 13mm socket. Note that the other bolt at the front does not need to be removed.

Loosen the hose clamp on the coolant pipe. Then, take a straight pick and insert it into the hose end. Move it around the circumference of the pipe to break the connection, which will make the removal of the hose easier. Pull the hose off the pipe and wedge it against the brake cylinder and the fuse box. Finally, lift the pipe off the engine and flip it towards the turbo.

Remove the turbo horn

To remove the turbo horn, you will need to follow these steps:

Firstly, disconnect the sensor on the manifold. This will give you access to the 10mm bolt that needs to be removed. Next, using a swivel socket and/or a 10mm wrench, remove the three bolts on the inlet horn. A useful tip for removing the left bolt is to take a long pick or screwdriver and apply inward pressure on the bolt. This can be done in combination with a speed wrench. Once all three bolts are removed, you can pull out the horn. It is also good practice to inspect your turbo wheel for any chips or other issues at this stage.

The next step is to disconnect the FPR connector. This is the white circle marked on the picture guide. Then, using a pair of pliers, remove the two fuel line clamps. These are marked in blue on the picture.

Now, you will need to make a tool for the next step. Take a screwdriver bit extension/drill bit and a 1/4" wrench. You will also need to purchase a T25 bit. This combination will work well for the next step.

The next step is to remove the three bolts from the FPR/CP3. Before you start, make sure you spray some penetrating oil on the bolts and clean the heads so that your bit will sit properly.

Once the bolts are removed, you can start to install the new FPR. It is recommended to use a dab of weatherstrip and gasket sealer on the bolt so that you can place it in the lower hole. This will allow you to pull the bit out once the thread has started. Once the sealer dries, you can either pick it out or leave it in so you can pull the "plug" out in the future if needed.

Finally, you can start to reassemble the parts, putting everything back in reverse order.

Frequently asked questions