99 Mustang Fuel Pressure Issue

Discussion in 'SN95 V6 Mustang Tech' started by NateM, Jun 10, 2013.

  1. I have a fuel pressure issue in a 99 mustang v6. I have replaced the fuel pump and filter twice without change in symptoms. The problem is the car starts hard (long crank before fire). Fuel pressure is at 30-40 psi when running (never an issue with running). When I finally get it started I get a puff of black smoke out the exhaust. Significant blackening of exhaust pipe noted. Fuel pressure at rail drops 1-2 minutes after shutting car off. Any suggestions of what to look at next?
  2. I'm wondering if you have a faulty fuel injector that's leaking fuel when the car's parked. Also, check the fuel rail pressure sensor, pressure regulator, and look for fuel leaks.
  3. how fast is the pressure at the rail dropping?
  4. No leaks I can see. Difficult to fully check injectors for leaks. The pressure drops to zero in 1-2 minutes after shutting off car.
  5. Replaced the pump and no longer drops and start right up.
  6. hey, I think I'm having a problem with my fuel pump.
    - fuel pressure with key on, no ignition; it was at 20 psi.
    - fuel pressure running idle at 33 psi.
    - turned car off waited 2 mins, put the key on, no ignition, and it read 40 psi. However, I left the key to on, and the pressure dropped about 1 psi a second to around 30 psi.

    Is this a dying fuel pressure?

    * my mustang has problems starting, with a rough start, it ignites but I have to keep the starting going until it finally starts, and then it idles rough. After I turn it off, and restart, it starts fine.