To find the location of the fuel pressure regulator, follow the fuel rail in the engine. The fuel rail usually leads to the fuel pump regulator. Fuel pump regulators are also commonly attached to the firewall of the car.
Symptoms of a fuel pressure regulator that is bad include blackened spark plugs, black smoke coming from the tailpipe and gasoline dripping from the tailpipe. If the car sputters and struggles while running on idle, that is another potential indicator of a bad fuel pump regulator.
Spark plugs are checked by removing one and inspecting it. One dirty spark plug could mean the engine is burning oil at that head, so check all of them. If the majority are sooty and black, it is a good idea to replace the fuel pressure regulator. Replacing the spark plugs with the fuel regulator is also recommended.
Black smoke coming from the tailpipe is a sure sign that the fuel pressure regulator is not working properly. Normal colors for tailpipe smoke are white and gray. If gas starts leaking from the tailpipe, it means that the fuel tank is overflowing or that the pressure regulator is faulty and is allowing gas to pass into the lines.