Fuel Pressure Gauge Cummins: Installation Guide

If you're looking to install a fuel pressure gauge on your Cummins engine, there are a few methods you can use. The most common approach is to utilise a tapped banjo bolt, which replaces the existing bolt that holds the fuel lines to the fuel filter assembly. This bolt is designed to accommodate a 1/8 pipe fitting, which is the standard size for most fuel pressure sensors. Another option is to install the gauge directly on the fuel rail, by unplugging the factory harness from the sensor and connecting the gauge's harness in its place. It's important to ensure that the harness is connected correctly to avoid any issues with starting the engine. When installing a fuel pressure gauge, it is recommended to use a snubber to protect the sensor from water hammer pulses and engine vibrations. The length of tubing used can also impact the accuracy of the gauge readings, with longer tubing providing more effective dampening of pressure pulses.

Using a banjo bolt to hook up the fuel pressure gauge

To hook up a fuel pressure gauge using a banjo bolt, you will need a tapped banjo bolt, which is commonly available from automotive vendors. This bolt replaces the factory bolt and is tapped for 1/8" NPT, allowing you to thread in a fuel pressure sensor.

The banjo bolt should be installed between the stock filter and the VP44. Specifically, it replaces the banjo bolt with the bleeder in it, which is one of the bolts that holds the fuel lines to the fuel filter assembly. When replacing the bolt, ensure that you use new sealing washers.

You can then attach the fuel pressure sensor to the banjo bolt. It is recommended to use 1/8" air brake line, which is rated for high pressure and can help dampen pulses. You can then attach the other end of the line to your fuel pressure gauge.

Some fuel pressure gauges may also come with a pressure snubber, which can be installed between the tap point and the sensor to further reduce pulses.

Tapping into the fuel supply at the VP inlet

Step 1: Source the Required Parts

You will need to source the appropriate fittings for this installation. Tapped banjo bolts or AN-type gauge fittings are recommended. These can be purchased from specialist vendors such as Vulcan Performance, Geno's, or Summit Racing. You will also need a fuel pressure gauge and any other necessary components, such as a snubber valve, tubing, and connectors.

Step 2: Prepare the Fuel System

Before beginning the installation, ensure that the fuel system is safe to work on. Relieve any pressure in the system and make sure there is no risk of fire or fuel leakage. Refer to your vehicle's manual or seek professional advice if you are unsure about this step.

Step 3: Locate the VP Inlet

The VP inlet is located between the stock filter and the VP44 pump. This is where you will be tapping into the fuel supply to install the fuel pressure gauge.

Step 4: Install the Tapped Banjo Bolt

Remove the existing banjo bolt at the VP inlet and replace it with the tapped banjo bolt that you sourced in Step 1. Ensure that the new bolt includes new sealing washers to prevent fuel leakage. This tapped banjo bolt will provide the port for connecting your fuel pressure gauge.

Step 5: Connect the Fuel Pressure Gauge

Now, you can connect your fuel pressure gauge to the tapped port on the banjo bolt. Follow the instructions provided with your fuel pressure gauge for the correct procedure. Ensure that all connections are secure and sealed to prevent fuel leaks.

Step 6: Test and Verify

Once the installation is complete, test the fuel pressure gauge to ensure it is functioning correctly. Start the engine and monitor the fuel pressure readings. Ensure that there are no leaks in the fuel system and that the gauge is providing accurate and stable readings.

Step 7: Optional - Remote Mounting

If desired, you can remotely mount the fuel pressure sensor to reduce the impact of engine vibrations and water hammer pulses. To do this, use a length of 1/8" air brake line or similar small-bore tubing to extend the connection between the tap point and the sensor. A snubber valve can also be installed at the tap point to further dampen pulses and vibrations.

By following these steps, you can successfully tap into the fuel supply at the VP inlet to install a fuel pressure gauge on your Cummins engine. This method will provide you with accurate fuel pressure readings and help you monitor the performance of your fuel system.

Using a manual gauge

To hook up a manual fuel pressure gauge to your Cummins engine, you'll need to follow these steps:

First, locate the banjo bolt on the fuel filter housing. The banjo bolt is the bolt that holds the fuel lines to the fuel filter assembly. You may need to purchase a tapped banjo bolt that is threaded for a 1/8" pipe fitting if your existing bolt is not already tapped. This type of bolt is commonly available from Cummins vendors. Be sure to also obtain new sealing washers to go with the bolt.

Next, remove the existing banjo bolt and replace it with the tapped banjo bolt. Ensure that you have properly sealed the connection with the new sealing washers.

Now, attach the sending unit of your manual fuel pressure gauge to the tapped banjo bolt. You may need to use a length of tubing, such as 1/8" air brake line, to connect the sending unit to the bolt. This tubing can be obtained from Cummins vendors or automotive stores. Be sure to use a snubber at the tap point to protect your sensor from water hammer pulses.

Finally, mount your manual gauge in a visible location, such as on the fender or column, and connect it to the sending unit using the provided wiring. Be sure to follow any additional instructions that came with your manual gauge for proper wiring and installation.

It is important to note that you should not use Teflon tape on fuel system fittings, as this is not the proper type of sealing material. Instead, rely on the sealing washers provided with your tapped banjo bolt.

Using an electronic gauge

To hook up an electronic fuel pressure gauge to your Cummins engine, you will need to purchase a suitable kit and follow the instructions carefully. Here is a step-by-step guide on how to do it:

Step 1: Purchase the Right Kit

Firstly, you will need to purchase an electronic fuel pressure gauge kit that is compatible with your Cummins engine. Make sure to buy a kit that includes all the necessary components, such as a pressure snubber, hoses, fittings, and a gauge. You can find these kits online or at specialised stores. When purchasing, ensure the kit is designed for your specific Cummins engine model and year.

Step 2: Identify the Fuel Filter Housing

Locate the fuel filter housing on your Cummins engine. This is usually found near the top of the engine and is often made of metal, with ports or bolts where you can attach the gauge. The fuel filter housing is part of the fuel system and will be connected to the fuel lines.

Step 3: Install the Tapped Banjo Bolt

To install the electronic fuel pressure gauge, you will need to replace one of the existing bolts on the fuel filter housing with a tapped banjo bolt. The tapped banjo bolt allows you to attach the gauge to the fuel system. Choose the bolt that holds the fuel lines to the fuel filter housing and remove it using the appropriate-sized wrench or socket. Then, screw in the tapped banjo bolt, ensuring it is tight and secure. This bolt will have a small tap or hole where you can connect the gauge.

Step 4: Connect the Gauge and Hoses

Now, you can connect the electronic fuel pressure gauge to the tapped banjo bolt. Screw the gauge's sender or sensor into the tapped banjo bolt. You may need to use a grease gun hose or a braided steel cable to extend the connection and protect the sensor from vibrations. Ensure all connections are tight and secure to prevent fuel leaks.

Step 5: Route the Wires

The electronic fuel pressure gauge will have wires that need to be routed into the cabin of your vehicle. Carefully feed these wires through a rubber grommet or existing wiring conduit to reach the desired mounting location inside the cabin. Ensure that you do not damage or kink the wires during this process.

Step 6: Connect the Wires to Power and Ground

Once the wires are inside the cabin, you will need to connect them to a power source and ground. Identify a 12V+ ignition source, such as a fuse in the dashboard, and connect the red wire from the gauge. For the black wires (ground wires), find a common metal point under the dashboard, or you can connect them to the vehicle's frame or engine.

Step 7: Test the Gauge

After everything is hooked up, start your engine and observe the gauge. Ensure that the gauge is reading the fuel pressure accurately and that there are no leaks in the fuel system. If the gauge is not working properly, double-check all your connections and refer to the kit's instructions.

By following these steps and carefully installing the electronic fuel pressure gauge, you can effectively monitor the fuel pressure in your Cummins engine. Remember to always refer to the specific instructions provided with your purchased kit, as there may be slight variations in the installation process.

Using a mechanical gauge

To hook up a mechanical fuel pressure gauge to your Cummins engine, you will need a tapped banjo bolt. This bolt will replace the existing bolt that holds the fuel lines to the fuel filter assembly. The tapped banjo bolt is designed for a 1/8" pipe fitting, which is the standard size for most fuel pressure sensors.

When installing the tapped banjo bolt, ensure that you use new sealing washers to prevent leaks. You can purchase this bolt from various vendors, such as Geno's Garage or Vulcan Performance. Some users also recommend using a banjo bolt with a port, as it provides a better reading.

Once you have installed the tapped banjo bolt, you can attach the fuel pressure sensor directly to it. If you are using a mechanical gauge, you will also need to install a snubber to protect the sensor from damage due to water hammer pulses. The snubber should be installed as close to the tap point as possible, and you should use small-bore tubing (such as 1/8" air brake line) to connect the sensor to the snubber. This tubing should be at least 5 feet long, as the distance helps to dampen the pulses and provide a more accurate reading.

After installing the snubber and connecting it to the sensor with tubing, you can then mount the sensor on a bracket and run the wires into the cab through the firewall. Be sure to ground the sensor to a common metal point under the dash or to the frame or engine.

Finally, to test your setup, start the engine and observe the fuel pressure reading on the gauge. If you notice any leaks or abnormal behaviour, shut down the engine and check your connections and tubing for any issues.

Frequently asked questions