One of the most important aspects of tuning involves the control of fuel. With Fuel injection, the computer handles most of this through it's control of the injectors. However, it is still up to the tuner to make sure there is a correctly calibrated Mass-Air meter (if applicable), the proper size injectors, and a fuel pump that can supply the necessary volume at right amount of fuel pressure. The key here is being able to monitor this fuel pressure. Not only does this aid the initial setting of the fuel pressure, but also helps to show the fuel pressure while driving. This can be very beneficial in showing when a pump can no longer keep up the demand, or even when a pump has trouble priming at start up. Either way, the following will show how to install an Electric Fuel Pressure Gauge.

As always, you should start by disconnecting the battery's negative cable. You will also want to make sure that you have all the tools and parts necessary to complete the install. It is also highly suggested that you let the motor cool before starting.



Unlike the typical mechanical fuel pressure gauge, an electronic gauge can be safely mounted inside the car. The main components of this system (fig. 1) are the Gauge, the Sending unit, and the Pressure Module (brain). The only part of this system that will be mounted outside is the Sending Unit. This is also the best piece to start installing.


Step 1.) Determine where you want to locate the Sending Unit and how you want to run it's cable back to the Pressure Module inside the car. Since we will be mounting our Sending unit back by the passenger side strut tower, we ran the cable through the ECU grommet (Fig. 2). While it's not exactly the easiest place to run the cable through, it is convenient. If you should run the cable through here, once you get a few inches into the car, you can reach up behind the heater box and pull the rest of the cable through. If you have trouble getting the cable started, try cutting back the end of the cable where the wires come out so that no wires stick out. If you make this cut about 45 deg. it can make this even easier to start through the hole you make.


Step 2.) With the cable run, the next step is to mount the Sending Unit. It will need to tap into the fuel supply line at some point, but can be remotely located if need be. In our case, we connected a 1/16" NPT to -4 AN fitting into the stock schrader valve terminal. We then ran a 16" section of -4 Line to behind the passenger side strut tower. This is where our install will be a little different. Since we were going to test how the readings of the Electric Gauge compared to our previous mechanical unit, we connected the Sending Unit to an adaptor just before the Fuel Pressure Isolator of our mechanical unit (Fig. 3). Otherwise, we would have used a -4 AN to female 1/8 NPT adaptor. All in all, once you have the Sending Unit tapped into the fuel supply, have the cable connected to the Sending Unit, and have the cable run back into the car, you are essentially done under the hood. You will, however, need to come back and check for leaks once you have completed the install.


Step 3.) At this point, you will need to determine where you want to mount the gauge itself. The most common options for the Mustang are either in an A-Pillar cup or in a Gauge Cage - which mounts in place of the center air vents (Fig. 4). Auto Meter provides the gauge with a good length of wire already attached to it, but if necessary you can extend this to where the Pressure Module is mounted. While you are running these wires, you will also want to run a set for the illumination of the gauge. For more information on the mounting of the gauge, please see our other gauge install articles.


Step 4.) The Pressure Module is what takes the signal from the Sending Unit and converts it to something that the gauge can use. Auto Meter also has another Pressure Module available that can also provide a recall for high and low readings. Which ever Module you chose, it can be mounted just about anywhere inside the car, although it's a good idea to make it a secure mounting to prevent possible problems. In our case, we decided to mount our Pressure Module just below the glove box (Fig. 7) so we starting routing all the wires to this location. Because we cut the end of the cable back, to make it easier to run through the ECU grommet, we needed to strip the end again to provide access to the wires (Fig. 5). If you need to do this, you will notice that there are actually four wires, wrapped in foil, with a drain wire (the one with no insulation).


Step 5.) Stripping the end of each wire about 1/4" to 3/8" you can then begin attaching them to the Pressure Module. (Fig. 6) You can also do the same with the wires from the gauge. While you are at it, you can add an extra set of wires (preferably a red and a black) for the power and ground connections. You will need to connect these to a key-on power and to ground, but can wait until you have the unit mounted to make these connection. Whenever you do make these connections, the easiest place to tap these two wires is to the key-on power and ground for the radio. This is also a good place to connect the illumination wires for the gauge as well.


Step 6.) With all these wires connected to the Pressure Module, it's a good time to go ahead and mount the unit (Fig. 7). The body of the Pressure Module has a set of mounting holes in case you wanted to mount it with screws, but in our case we simply used a couple of strips of 3M mounting tape (double stick foam strips).

This essentially finishes the install and it's time to test the system. Start by priming the fuel system a few times to get everything pressurized. You should see the gauge reacting as you do this, but make sure to check for leaks before you start the car. Perhaps a little overly cautious, I also recommend double checking for leaks after the first time or two that you go driving as well. With everything done, you can now make use of your new fuel pressure gauge.

For all those who may be a little concerned with the accuracy and responsiveness of the new Auto Meter Electric Fuel Pressure Gauge, I can assure you that it's nothing like some of the other gauges out there. In our testing, it proved to be just as quick and accurate as a mechanical gauge. While this new gauge certainly isn't cheap, it is a very good piece of equipment and I highly recommend getting one.