Fuel Pressure Regulator
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Holley Fuel Pressure Regulator

Part No. 12-804 Warranty Details  

Fit of this part varies by vehicle & equipment specs Type of Fit

Fuel pressure regulators are used to adjust for fuel pressure requirements of various carburetors. Too much fuel pressure for a given needle and seat assembly may cause flooding or drivability problems. 3/8 inch NPT ports. Allows adjustment of fuel pressure to compensate for high flow fuel pumps.

Product Features:
  • 3/8 in. NPT Ports
  • .220 in. Restriction
  • Incl. Mounting Bracket
  • Low Pressure 1-4 PSI
  • Chrome Finish
  • Not Alcohol Compatible
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Ask a question, get answers from real customers and in-house experts. Or contact Customer Care by email or call 1-877-238-2623.

5 Questions | 5 Answers
Displaying questions 1-5
  • Q:

    I have placed two model 12-804 regulators on my 1939 ford 221 cu in engine. regulator goes to a brand new stock mechanical fuel pump for this model engine. Both regulators will not reduce the fuel pressure below 6 psi. I thought the first regulator was defective, reason for buying the second one. Is my problem because I am using the origional mechanical fuel pump also, this is causing " back pressure " not allowing the pressure to drop below 6 psi ? Would I be better off removing the mechanical pump & using only the electric fuel pump I have installed in the rear area of the car. (I was told pressure should be around 2 psi.) Car runs ok, does not flood out. My concern is blowing the diaphragm in the mechanical pump.......
    Asked on 7/21/2015 by Bertie from Plymouth , Ct

    1 answer

    • CUSTOMER CARE

      A:

      That's a great question Bertie, I will be happy to help. This sounds like a trial and error process of seeing what works and what doesn't. I would first try it with just the electrical pump alone, if its still too high then I would try just the mechanical pump alone. We could always try a third regulator in-line. I hope this helps. Be sure to stop at one our Advance Auto Parts store if you have any questions to see if anyone else has knowledge of this kind problem you're having. Holly also has an instructional pdf file here is the link http://www.holly.com/data/Products/Technical/199R7914-3rev6.pdf

      Answered on 7/30/2015 by JJMO ASE Parts Pro from AAP
  • Q:

    Does this model have a port for a return line back to the tank?
    Asked on 5/7/2014 by Rob

    1 answer

    • CUSTOMER CARE

      A:

      I'm happy to help, Rob! This Holley Fuel Pressure Regulator does not include a bypass or return line to your fuel tank. Holley Part No. 12-803BP (the BP designates bypass) has the return line. For further details about the installation of the part, Holley has instructions here: http://www.holley.com/data/Products/Technical/199R7914-3rev6.pdf

      Answered on 5/9/2014 by Heath, ASE Parts Specialist from AAP
  • Q:

    i am going from tbi to carb.i want to keep factory electric fuel pump(22psi) will this regulator be able to handle it to lower pressure to about 8 psi?
    Asked on 11/28/2013 by alex from groton ct

    1 answer

    • CUSTOMER CARE

      A:

      Hi Alex, good question! this part is able to handle low pressure to about only 4 psi. Product features. Low Pressure - 1-4 PSI, High Pressure - 4.5-9 PSI. To locate the exact fuel pressure regulator, please provide us the year, make, model and engine size of your vehicle.

      Answered on 11/28/2013 by Steve from AAP
  • Q:

    Holley website list 12-804 as having a range of 1-4 psi. You previous answer to the other quest was that this regulates from 4-9 PSI. What are the actual specifications?
    Asked on 9/2/2012 by Rob from N.C.

    1 answer

    • CUSTOMER CARE

      A:

      Sorry for the confusion caused. The Holley Fuel Pressure Regulator (Part No. 12-804) is a Low Pressure (1-4 PSI) regulator. We will have the previous answer corrected. For any further assistance please feel free to call us at: 1-877-238-2623 or visit the nearest Advance Auto store and one of our representatives will gladly assist you with any questions or concerns you may have.

      Answered on 9/2/2012 by John the Car-Doc from AAP
  • Q:

    does this have adjustable pressure or is it preset
    Asked on 8/8/2012 by derail

    1 answer

    • CUSTOMER CARE

      A:

      This Holley Fuel Pressure Regulator (Part# 12-804) is used to adjust for fuel pressure requirements of various carburetors. This regulator adjusts from 4.5 to 9 psi. For further assistance, please feel free to call us at 1-877-238-2623 or visit your nearest Advance Auto Parts store and one of our representatives would be more than happy to assist you.

      Answered on 8/8/2012 by Rick from AAP
Displaying questions 1-5

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