I have a 1988 GTU normally asperated and fairly stock. I have been testing the fuel components to find out why my fuel pressure does not hold after the car is shut down. Following the manual, everything tests fine with the exception of the FPR. I have the fuel gauge tee in the line after the fuel filter, the injectors are wired in the rails to check for leaks there, I caped off the return line at the fuel pressure regulator so I basically get fuel pump pressure in the whole system. When the pump is shut off the pressure holds at pump output. When the cap is removed the pressure drops to 0 in a matter of about 5 seconds. The book I have states that the Fuel pressure regulator should hold at least 18psi after about 5 minutes. With the outlet of the FPR flowing into a can, and the pump running and shut off, the pressure drop is the same to 0 in 5 seconds. I have tried 3 other used FPR's and they all do the same thing. Is this correct, or do I have 4 engine flooding prevention devices?