to check the fuel pressure regulator pull off the little vacuum hose that runs from under the throttle body to the regulator which is on the end of the fuel line on the driver's side of the inlet manifold. If the inside of the hose is wet with fuel or smells noticeably of petrol then the vellum in the regulator has failed. Easily replaced.
When the vellum fails the excess fuel is sucked into the throttle body through the vellum instead of returning to the fuel tank via the return line.