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Adjustable Fuel Pressure Regulator

Discussion in 'The Garage' started by rotorjockey, Jun 1, 2006.

  1. rotorjockey

    rotorjockey Registered Member

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    I have a 383 stroker crate motor with some add ons, including edelbrock intake and larger throttle body. I added a perfect power piggyback system and was told that I am fuel limited right now and need a variable fuel pressure regulator to fix this problem. Are these pressure regulators automatic or do I have to change the settings as needed? Are there any recommendations as to what kind I should get. This is a new area to me.
    Thanks.:confused:
     
  2. sled_dog

    sled_dog 1 ton status

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    there ARE vacuum pressure regulators. They came on the marine engines. Can't find any online at this second.

    What is a "perfect power piggyback system"? I consider myself pretty up on high performance stuff... and I've never heard of that.
     
  3. Triaged

    Triaged 1/2 ton status

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    Is this a TBI engine? If it is the factory regulators are adjustable...but they put a tack weld on it after setting it. Grind off the tack weld and it will be adjustable again...for free!
     
  4. stkcode

    stkcode Registered Member

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    Presume where talking about a TBI here and your referring to a VAFPR (vacuum-adjustable fuel pressure regulator). How did who ever told you that your fuel was limited come to this conclusion? If your running rich at idle and lean at WOT, then a VAFPR would probably be about right.
     
  5. rotorjockey

    rotorjockey Registered Member

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    go to www.perfectpower.com and you can find out about the piggyback system. I have the smt6. The shop that installed it, Virginia Speed, could not set it correctly because of the fuel pressure regulator problem, so they gave it to me pumping as much fuel as it can.
     
  6. mouse

    mouse 1/2 ton status

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  7. Blue85

    Blue85 Troll Premium Member

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    Well all fuel pressure regulators are adjusted by manifold vacuum. Otherwise, the amount of fuel injected for a given pulse width would vary with engine load, making it difficult to fuel correctly. When we say an engine has "44 psi" of fuel pressure, that means at WOT. When there is vacuum in the manifold the fuel pressure is decreased by that amount. That way the total pressure across the injector is always the same.

    To adjust the fuel pressure, you just need a way to adjust the tension on the spring inside the regulator. You can usually modify ones that aren't adjustable from the factory, but you need to ensure that your modification doesn't create a vacuum leak.

    If the post about the factory TBI regulators just having a tack weld on the screw is true, then your problems are solved.
     
  8. Triaged

    Triaged 1/2 ton status

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    You are forgetting that TBI injectors are not in the manifold. They are above the throttle blades and never see anything but atmospheric pressure. For this reason just about all TBI engines do not have vacuum referenced pressure regulators. Only some marine and some aftermarket applications have the vacuum line.
     

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