Honda Repair: 1990 code 16, fuel pressure regulator, strange quirk

Question
I recently bought a 1990 honda civic DX with 135K. The car has a strange quirk, you can start the car and it runs good. However if you shut the engine off and then quickly try to restart it, it will not start.  It loses power to the fuel injectors and sets a code 16. I have ohmed out the injectors and the are within spec's, and checked the grounds and harness as best as I could. I even swaped out the computer with the same result.  If you turn off the ignition and remove the key for 20 seconds and then try to restart, the engine will start and run fine with no code. Any ideas as to the problem?  

Answer
Jack:
I would check the fuel pressure regulator, it may be going out. The regulator makes sure there is fuel in the lines so you are not pumping fuel from the fuel tank when starting. Also you may want to check the fuel pump as it may be going out.
Good luck.
Bill