Removed old fuel pump serviced it and put it back in. Fuel pressure went from 50 to 15 so that was a bust.Bit the bullet and bought new pump again. This one is working fine. After original pump stopped holding pressure when off, I got a replacement that also did the same thing, i returned for exchange and the exchanged one showed same symptoms so i figured it was a different problem. I troubleshot for a year. then decided to take pump apart to find anti back flow valve, I screwed pump pressure up and had to get a new one. New one works fine. It was defective replacements all the time.