99 Mustang Fuel Pressure Issue

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

  1. NateM

    NateM New Member

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    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. Zhen

    Zhen New Member

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    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. madspeed

    madspeed Colonel Mustard
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    how fast is the pressure at the rail dropping?
     
  4. NateM

    NateM New Member

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    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. NateM

    NateM New Member

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    Replaced the pump and no longer drops and start right up.
     
  6. slow6

    slow6 New Member

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    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.
     

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