Fuel pressure regulator Q's

Discussion in 'The Mixing shop.' started by BUICKRAT, Mar 28, 2019.

  1. BUICKRAT

    BUICKRAT Torque Rules!

    Hey guys, my billet mechanical pump is pushing 10 psi, way too high for my liking. Is a bypass style regulator mounted on the back end of the fuel log kosher? I thought I read somewhere that bypass style regulators should not be used with mechanical pumps, only electric ones? Thoughts? Ideas? Thanks in advance.
     
  2. Bens99gtp

    Bens99gtp Well-Known Member

    I dont see why it would matter 10 psi is too much by a little bit. I run 7.5 to 7.75 on my holleys with a bypass regulator.
     
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  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    My CV pump occasionally makes 10 psi, usually when I first start the engine cold. Neither my QJ or AED 1000 seem to mind it.
     
  4. BUICKRAT

    BUICKRAT Torque Rules!

    Ben, are you running a mechanical pump?

    Larry, some 4500 Dominators can be finnicky about fuel pressure. Some dragster guys say 5 psi is ideal. I would like to be able to adjust fuel pressure as part of my ongoing diagnosis.
     
  5. DasRottweiler

    DasRottweiler -BuickAddict-

    Larry, when you ran a mechanical with an electric pusher wired to the kickdown switch, did you utilize a regulator with a return line , and if so where did you plumb it in ?
    And is that something Buickrat could benefit from since he has a good mechanical pump already? JIM
     
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  6. Bens99gtp

    Bens99gtp Well-Known Member

    mine is electric, but I really dont see why it would matter?????
     
  7. hugger

    hugger Well-Known Member

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  8. BUICKRAT

    BUICKRAT Torque Rules!

    Ben, I'm not sure it does matter, but I have read a few articles saying it does, so I'm trying to verify it.

    Thanks for the link, Hugger. I may give aeromotive a call today.
     
  9. Bens99gtp

    Bens99gtp Well-Known Member

    I would think that mechanical pumps are spikey in their pressure due to being pumped only once per revolution. but that being said at idle it being pumped 600-1000 per minute. so their shouldnt be any lack of fuel......the bypass regulator should be able to smooth that out.......and if yours is doing 10psi, if you cut it down to 8ish you should have fuel always returning and in such pretty steady pressure.

    at 3000rpm you will be getting lots of fuel return.

    if I'm not mistaking, mechanical punps have to have some form of pressure bypass systems built into them.......I know the pump on my boat motor......454 bbc......I had a running issue and put a gauge inline sometimes it would read just under 7, sometimes it would run 11psi and when it did or course it flooded my webber carb on it.
     
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  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    No, the Holley pusher pump was self regulated to 7 psi, and I did not have a fuel pressure gauge at that time. Never had a problem with flooding, so I guess ignorance is bliss.:)
     
  11. BUICKRAT

    BUICKRAT Torque Rules!

    Ok, trick question:

    Can the pressure regulator be mounted at the back of the fuel log? My regulator has 'in', 'out', and 'return ' ports on it.

    Details:

    Mechanical pump supplies fuel to front of fuel log.

    The back of the log supplies the 'in' port of the regulator. (past the carb feeds)

    The 'out' port of the regulator is blocked off.

    The 'return' port goes back to the tank.

    Anyone else running a dominator on their Buick?
     
  12. Bens99gtp

    Bens99gtp Well-Known Member

    no, that wont work with that style. there are some that do mount on the log.

    but if yours has an in/out/return.... the regulated pressure will only be on the out port.


    I'm going to put my stk tank in but have it sumpped instead of the small 2 gallon cell under the hood I've been using and when I do I'm putting my regulator clear at the back close to the pump so I have the extra expense to run the return line all the way back to the rear of the car.

    there are lots of buicks running dominators
     
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  13. BUICKRAT

    BUICKRAT Torque Rules!

    Thanks Ben. Guess I will find a different regulator. The main reasoning I have for putting the regulator after the log is to keep the fuel cooler.
     
  14. Bens99gtp

    Bens99gtp Well-Known Member

    you could put the regulator in front of the log.......fuel from pump into reg,the the out going into the log, and the return then and put your gauge at the rear.......this way the carb and log and gauge is after the pressure drop.......not b4
     
  15. hugger

    hugger Well-Known Member

  16. hugger

    hugger Well-Known Member

    When I had a dom on mine I ran an aeromotive 13204 iirc. Worked as it should no issues, when I was procharged I ran a line to each bowl with a different aeromotive reg
     
  17. Bens99gtp

    Bens99gtp Well-Known Member

    I guess by reading that you can put the regulator after the log and carb.......I was under the impression that only the out side would see the constant decreased pressure and that the in side would still be seeing the higher pump pressure????


    I guess the regulator not only dros the pressure to the out side but also in the side but I also bet this would be effected by how big the pump was feeding it

    my big pump makes some 20psi on the outlet side going to regulator........damn it now I want to put a gauge b4 to see what's going on.......thanks Ethan for making me think at midnight just b4 bed........lol
     
  18. BUICKRAT

    BUICKRAT Torque Rules!

    Thanks, Hugger. looks like it's a go!

    Ben, I also am going to put a gauge before and after the regulator, just to ease my mind.

    Thanks to all who have responded, this board is truly a huge asset to all.
     
  19. BUICKRAT

    BUICKRAT Torque Rules!

    OK regulator is all plumbed, 3/8 return, pressure adjusted to 6psi, gonna take it for a run this week. Wish me luck, I'm getting tired of changing out 8 qts of oil+additive every time it pukes fuel!
     
  20. BUICKRAT

    BUICKRAT Torque Rules!

    Update...took the car for a few good rides today. No issues so far! Regulator needed adjustment twice, but so far pressure is steady around 6.5psi, bleeds off slowly when I shut it down. I'm feeling pretty optimistic (cautiously). The next dry day we have, I'm going to take it for a good cruise and see how it is. I wanna thank you guys for all the input and advice. Now I can get back to burning gas and shaming chevelles/crustangs/etc.:cool:
     

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