To install a fuel pressure regulator, disconnect the fuel line to the old regulator, install the gauge, and then reconnect the fuel pump to the fuse. Disconnect the battery, and install the new regulator. Before starting, make sure to wear proper safety equipment, including gloves and eye protection.
Start the engine, and check the gauge connections for leakage. Turn it off, disconnect the fuel pressure regulator from the vacuum hose, and attach a vacuum pump to the fuel pressure regulator. Read the gauge with the vacuum on and off. The pressure should decrease when the vacuum increases and should increase when the vacuum decreases. Check the pressure when the engine is idle, and compare the read-out to vehicle specifications.
Connect the vacuum gauge to the fuel pressure regulator vacuum hose, and turn on the engine. If all is good, the new fuel pressure regulator can be installed, but first disconnect the battery. Install new O-rings onto the fuel pressure regulator, and ensure they are lubricated with a light coating of oil. Tighten up the fuel pressure regulator bolts until they are secure, and test the new installation.
To test the new installation, use the vacuum gauge, and make sure the readings match the previous numbers and specifications from the manufacturer of the vehicle.