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low fuel pressure

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  • low fuel pressure

    1988 300zx turbo

    low fuel pressure problem - running rough, stalling, loss of power

    1. code 42 - fuel pressure regulator
    2. swapped fpr from an 88na. After the swap still got code 42 and still no pressure. Also, "possible problem" fpr worked fine in 88na after swap, so both fpr's working ok. rule out fpr (Peculiar--->(when removing good one from 88na, fuel sprayed everywhere for a quite a while....but when removing the "possible problem one" from the turbo there was no pressure)
    3. I think I got (code 42-fpr) because the fpr at least needs pressure to work
    4. I can hear fuel pump running.
    5. AFM clean burn test ok

    Need help.........THANKS!!!
    I wouldn't drive anything else.

    88 Turbo

  • #2
    Code 42 aint the FPR, according to the manual it's the fuel temp sensor.

    How's long since the fuel filter was changed?


    • #3
      You are right but, the fuel temp sensor is on the FPR so if I swap a FPR, I also swap a FTS, right? I assumed if one works in one car it should work in the other. FTS probably doesn't read correctly without fuel pressure, thus the code 42.
      I also checked continuity from terminal 15 to the FTS, ok

      rule out:

      fuel filter
      air filter
      AFM clean burn test ok
      plugs, wires, cap & rotor
      gas changed, car sat for 4 years
      can hear fuel pump running

      Thanks for the help, I'm stumped
      I wouldn't drive anything else.

      88 Turbo


      • #4
        FTS is virtually useless and has no effect on your no fuel pressure issue... What is your fuel pressure gauge reading when you try to start the car? If you can hear the pump running then it's either a clogged supply line or a faulty pump or fuel pump wiring. Pull the supply line off and put it in a gas can, turn on the ignition and make sure you are getting fuel flow. If you get flow but it won't build pressure then check voltage across the pump while it is running (wires are on pass side in the hatch). If that's over 12V, then replace the pump.


        • #5

          I was mistaken abot the low pressure prob

          Put a fuel gauge on it and got 34-37 all the time,
          tank, pump and gas O.K. my mistake

          Thanks for all the help.
          I wouldn't drive anything else.

          88 Turbo