[Zephyr]

Gentleman
I posed this question on another board and the two replies I recieved said I have a faulty fuel pump or a faulty fuel pressure regulator.

We just bought a 1998 Mustang 3.8 liter V6 auto. with 90,000 miles. The seller said that on occasion the engine cranks a little longer than usual before it starts if the car sits for a while. (Some people are just plain honest) I pressure tested the pump and sure enough I had to turn the key on and off two to three times quickly to build up pressure in the injector rail. The car starts quickly and runs flawlessly when I follow this procedure. When idling it maintains a steady 32psi but when the engine is shut off pressure in the rail returns to zero within seconds. Removing the vacuum line from the regulator increases fuel pressure in the rail as it should. The engine shows no signs of fuel starvation at highway speeds and I don't believe the injectors are leaking down because there is no sign of flooding when it does start. I do suspect a bad fuel pump but could the fuel pressure be leaking past the regulator when the engine is shut down? Thanks!

[GTRaptor]

Most probably the regulator, and it is the least expensive part of the 2, so change it and see what happens.

[lcurle]

Also you might want to try turning the key to on but not start to turn the fuel pump on before you start to crank it over, this may build up pressure in the lines.

[Zephyr]

Just an update,

Replaced the fuel pressure regulator with no improvement. It turned out to be the fuel pump. When I removed the pump a small round very fine screen approx. 1¼ inch in diameter was found in the bottom of the fuel tank. It snapped (rather weakly) into the bottom of the pump module. It covered a rubber check valve and a fair amount of sediment found its way into the assembly. I had two options, flush things out the best I could and reinstall the pump and screen or replace the whole unit. Not wanting to drop the fuel tank a second time if I was wrong I decided to flush out the tank and replaced the entire module. No local auto parts stores including Napa could get this module so I had to go to $$ Ford $$. Now the pressure in the rail holds after shut down and the engine no longer cranks excessively before starting. All is good! Thanks