DIY: Fuel Pressure Regulator on Infiniti QX4 and Nissan Pathfinder (R50)

How to change the fuel pressure regulator on a 2001-2003 Infiniti QX4 and Nissan Pathfinder (R50). May apply to earlier models.

I purchased  Standard Motor Products PR59 Pressure Regulator to replace the old OEM regulator.

Step 1: Remove the fuel pump fuse. Pull out the coin tray to access the fuses. The fuse is the second column from the driver door, and the fourth one down.

Step 2: Remove engine cover. Three 10mm bolts. Location is highlighted by red arrows. 

 

Step 3: Locate the old fuel pressure regulator. The FPR is located in the bottom left corner underneath the engine cover. The old FPR is removed in the picture below.

Old and new fuel pressure regulator side by side picture. The new one is a silver color.

Step 4:  Remove old fuel pressure regulator.

Loosen the hose clamp with a Phillips screwdriver and remove hose attached to the long tube of the FPR. The hose may be difficult to remove so a moderate amount of pull is necessary to get it off.

The hose that is bent to 90 degrees and attached to the short tube is removed by simply pulling it off.

The fuel pressure regulator is held into place by two Phillips screws. The screws I had were extremely soft and I could feel that they were going to be stripped if I tried loosening them by hand. I used a electric driver and put it on the lowest speed to remove the screws. Please be careful in removing the screws and do your best to not strip them.

Picture for reference. Note that this is the new Fuel Pressure Regulator that is installed.

Once the screws are out, pull the fuel pressure regulator out. I had some difficulty removing the old FPR and required a lot of force to pull it out. Also, there will be fuel gushing out. To minimize this, some people have recommended starting the car a few times after the fuel fuse has been pulled to suck as much fuel out of the lines.

Step 5: Install new fuel pressure regulator.

Make sure new FPR has a rubber seal. See picture below for location of seal.

Put new FPR where the old FPR went, install the two Phillips screw making sure not to strip them. Attach the two hoses and tighten the clamp with a Phillips screw driver on the long hose.

This is what it should look like in the picture below.

Step 6:  Install engine cover with the three 10mm bolts.

Step 7: Re-insert fuel fuse and start car.

Notes: Fuel may gush out when pulling the hoses or the FPR out. I put red shop rags around the area to soak up any fuel.

There is another fuel pressure regulator right next to the one I changed. I would like to change it however I do not know how to remove the hose clamp as it is not attached with a Phillips screw.

Again, take precaution removing the Phillips screws. They were extremely soft on my car.

I attached a link to the FPR I bought on Amazon. It is not OEM but looks identical and has been working fine ever since. It comes with a 60 month/50,000 mile warranty in case there are any issues. It is in the $50.00 range whereas the dealership wanted $78.00.

Please leave a comment below if the procedure is the same for earlier Pathfinder and QX4s.

Why change a FPR and symptoms of a bad FPR:
Car does not run smooth.
Car is running rich and strong smell of gas coming out of exhaust.
Blackened spark plugs.
Poor gas mileage.

In my case, my QX4 would stutter on start up and was running very rich. There was an overpowering gas smell when starting and the gas mileage was terrible. 
 

Note: The nuts and bolts may be very difficult to remove after years of grime and rust. Do not risk stripping or damaging the hardware. I highly suggest using penetrating oil to help in removal. Kroil and PB Blaster are good penetrating oils.