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  1. #1
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    Default Fuel pressure regulator

    84 Ltd lx 347 t5, newly installed engine, aeromotive fuel pressure regulator, pressure does not change when you remove vacuum line from regulator and/or plug the vacuum line.

  2. #2
    Moderator wraithracing's Avatar
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    Quote Originally Posted by bgriff View Post
    84 Ltd lx 347 t5, newly installed engine, aeromotive fuel pressure regulator, pressure does not change when you remove vacuum line from regulator and/or plug the vacuum line.
    I assume it is adjustable? What is the current pressure? Do you have vaccum at the regulator? Have you attempted to adjust the regulator?
    ​Trey

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  3. #3
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    It has an Edelbrock Pro flo system. The fuel pressure regulator is adjustable, and it does adjust. I do have vacuum at the fuel pressure regulator, but when I pull the hose the pressure does not change.

  4. #4

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    Is the car running ok?
    79 Zephyr, 4.6L 4v/4r70w swap, with team z front and rear suspension, 8.8 and upgraded brakes and coil overs. Running Holley Terminator X Max.

  5. #5
    Moderator wraithracing's Avatar
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    Quote Originally Posted by bgriff View Post
    It has an Edelbrock Pro flo system. The fuel pressure regulator is adjustable, and it does adjust. I do have vacuum at the fuel pressure regulator, but when I pull the hose the pressure does not change.
    We are going to need more information to try and help you. Couple of questions first . . . Is the FPR supposed to have straight manifold vacuum or ported vacuum? What is the current fuel pressure? What is it supposed to be set at? Have you adjusted the FPR either direction? Does fuel pressure change with the vacuum line hooked up as throttle is increased? How does the engine run currently?
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  6. #6
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    The engine seems to be running rough at idle and very rich. The for is plumbed to straight manifold vacuum. The current fuel pressure is 58 psi which is what Edelbrock recommends on the pro flo system. I will check on the for adjustments.

  7. #7
    FEP Super Member erratic50's Avatar
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    What is your pump and return setup?

  8. #8

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    As far as I know Aeromotive does not make a FPR without a vacuum port for fuel injection applications. I double checked myself and all their current FPR's show vacuum ports.

    This is from Aeromotive's FAQ page:

    5.) What is the barb fitting in the regulator cap used for? How and where should it be connected if I choose to use it, and what should I do with it if I don’t?
    All Aeromotive, EFI bypass regulators incorporate the necessary design to allow the regulated fuel pressure to be vacuum/boost referenced on a 1:1 ratio with PSI. Always connect a vacuum/boost line between the intake manifold and the regulator cap for port fuel injected engines, forced induction or natural aspirated, where the fuel injector discharges into the intake manifold after the throttle body. Remember to set base fuel pressure with the vacuum/boost line disconnected from the regulator. For TBI engines or applications where the injector discharges above or before the throttle blade(s), the vacuum/boost port should be left disconnected and open to atmosphere, never blocked or plugged. Note: the ratio of 1:1 is measured in PSI. When looking at a vacuum gauge, it is normally calibrated in “HG or inches of mercury. It takes roughly 2”HG to equal 1 PSI. So, for example, when the vacuum gauge reads 10”HG, with the engine at idle, fuel pressure will drop 1/2 of that or 5 PSI.

    For more detailed information on EFI regulators and vacuum/boost referencing fuel pressure, see Aeromotive Tech Bulletin TB-202 at www.aeromotiveinc.com under the Tech Help, Tech Bulletin section.

    Hopefully some of that info will help. You could also have and issue with the FPR in that is has a bad diaphragm. That happened on my Kirban and I ordered a rebuild kit for it and solved the problem.
    Last edited by Aerocoupe; 10-26-2021 at 01:32 PM.
    http://vb.foureyedpride.com/attachme...1&d=1418488062
    '83 351W TKO'd T-Bird on the bottle

    http://vb.foureyedpride.com/attachme...2&d=1418488063
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  9. #9

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    Won't let me edit my previous post but you should get a vacuum gauge and see if you are actually getting vacuum on the hose that you are connecting to the FPR.
    http://vb.foureyedpride.com/attachme...1&d=1418488062
    '83 351W TKO'd T-Bird on the bottle

    http://vb.foureyedpride.com/attachme...2&d=1418488063
    '93 331W Mustang coupe that beat your mom's LTD

  10. #10
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    Yes , the fpr is hooked at the vacuum port. I will check on everything else when I get back in town.

  11. #11
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    The fuel pressure regulator reads 58 psi, which is what Edelbrock recommends. Installed out of the box it read 58 psi with zero adjustments. I have tried to increase and decrease the pressure with the vacuum line disconnected and plugged with no change in pressure. The fuel pressure does decrease when I hit the throttle.

  12. #12
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    The aermotive fpr and gauge were new when I installed the engine. I have a Walbro in tank fuel pump with 6AN fuel lines. The fuel pressure was at 58 psi, which is what Edelbrock recommends, on the initial installation without any adjustments. I have tried to increase or decrease the fuel pressure with no success. The fuel pressure does drop when I push the throttle.

  13. #13
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    For what it's worth I bought an Aeromotive regulator years ago and it was bad out of the box. I was so pissed I threw it into the canal behind my backyard.
    A smarter, more frugal me (read older and more mature... lol ) would have exchanged it with the retailer.
    '85 GT

  14. #14

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    Nvrmnd sorry
    Last edited by massacre; 11-18-2021 at 08:29 PM.
    79 Zephyr, 4.6L 4v/4r70w swap, with team z front and rear suspension, 8.8 and upgraded brakes and coil overs. Running Holley Terminator X Max.

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