The fuel pressure regulator maintains the pressure in your vehicle's fuel system. A bad regulator needs to be replaced, or it will affect your vehicle's ability to run. How the regulator is attached to the system can vary greatly depending on your make and model. What follows is a general procedure, but you should check an automotive repair guide written for your specific vehicle for more explicit details.
Relieve the pressure from the fuel system. Open the fuel cap, remove the fuel pump relay from the engine compartment's fuse box, then start the engine and let it run until it stalls (it will take a few seconds, tops). Disconnect the negative battery cable.
Clean away dirt or debris from all lines and connectors attached to the fuel pressure regulator, then disconnect them. This varies depending on the vehicle and can include a vacuum line connected to the regulator, electrical connectors to the injectors, and fuel supply/return lines that are disconnected at the fuel rail. Most of these use quick-connect fittings.
Remove any bolts if the regulator is mounted to the engine by them and remove the fuel pressure regulator. On some vehicles, the regulator is part of the fuel pump module. In this case, remove the module's upper and lower sections, then disconnect and replace the section with the regulator.
Use a new O-ring with the replacement regulator if it uses one and lubricate the ring with a small bit of engine oil. Place the new regulator in position in the engine and tighten any bolts. Reconnect all lines and connectors attached to the regulator.
Re-pressurize the fuel system. Reconnect the battery cable and fuel pump relay, turn the ignition switch to the On position for a couple of seconds, then turn it back off. Repeat the ignition switch another two or three times.
