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Technical Fuel Pressure Regulators and Issues and Options

Discussion in 'The Hokey Ass Message Board' started by Blues4U, Jul 6, 2017.

  1. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,536

    Blues4U
    Member
    from So Cal

    That's a good point, thank you. Holley makes a bypass style regulator, the model # is 12-803BP, but that is a higher pressure regulator, 4 - 7 psi. The 12-804 that I used has pressure settings of 1 - 4 psi. I suppose it would work just fine at the lower setting. For someone with a return line already plumbed, or who wants to add a return line that is a good option, there are benefits to that. It helps purge air from the line, it helps keep the fuel supply cooler, and it relieves pressure and eases the load on the pump. For positive displacement pumps I think it is a requirement.
     
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  2. Stogy
    Joined: Feb 10, 2007
    Posts: 12,177

    Stogy
    ALLIANCE MEMBER

    I am questioning the fuel pressure...going to my Holley 94 Carbs on Edelbrock X1 on a 327 with mechanical fuel pump...


    0_20190624_190047.jpg

    :rolleyes:...regulator at lowest setting...which is less than 1


    0_20190624_190045.jpg

    :rolleyes:...the needle at 600rpm fluctuates between 9- 10psi...is that too much psi and if so the regulator suspect?

    I am only running center two carbs Holley 94's

    The carbs are running wet and you can smell the raw fuel and it seems to be running rich...
    I'm thinking if the regulator is at 1 the gage should read similar psi...correct?

    Thanks in advance...;)
     
  3. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,536

    Blues4U
    Member
    from So Cal

    In my opinion Yes, that is too much pressure, though some may want to argue. And in my experience those regulators are junk. They regulate pressure poorly, and they fail, and when they fail they start leaking. The last one I used started leaking a steady stream of fuel, which blew back up onto the windshield. Definitely not a great feeling to have raw gas blowing around the engine compartment.
     
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  4. Stogy
    Joined: Feb 10, 2007
    Posts: 12,177

    Stogy
    ALLIANCE MEMBER

    So Blues are you still running that Holley Regulator and how is it working?
     
    Last edited: Jul 15, 2019
  5. Stogy,
    Looking at your two pictures, I can't tell if your gage is before or after your regulator...
     
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  6. Stogy
    Joined: Feb 10, 2007
    Posts: 12,177

    Stogy
    ALLIANCE MEMBER

    The psi gauge is at the fuel block after the Regulator...the Regulator is between that and the Fuel Pump...

    Funny I was just reading another post on the Holley, #12-804 and he was running Smallblock and had 9 psi which is my problem now...This is at idle if I add rpm will it go down?

    He thought they shipped him the wrong one but he said no. One suggestion was to run a bypass to the tank...I've got three years out of the dial setup (car was built in 2010 so more like 9 yrs) and adding something else sounds a like bit more this and that...But when you see raw fuel on the base of the carbs or on its no joke...

    Heres the other post...

    https://www.jalopyjournal.com/forum/threads/holley-low-pressure-reg-woes-12-804.520982/
     
    Last edited: Jul 15, 2019
  7. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,536

    Blues4U
    Member
    from So Cal

    Yes I am, and as far as I know it's working as intended. I haven't check fuel pressure lately, I'll have to check it and report back. After I repair leaking trans oil cooler lines. (it's always something.... :D)
     
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  8. Stogy
    Joined: Feb 10, 2007
    Posts: 12,177

    Stogy
    ALLIANCE MEMBER

    Did you run a bypass line or just line in and line out? Sorry to bother you while your fixing your pipes...;)

    I'll have to get crafty with locating Holley the Ugly Gauge...:D...she's not in period...:confused:...:p

    I was just thinking maybe you could get a small chrome cover thats old or looks 62ish and make it fit as a decorative cover...

    I think I ran 1 (.5 it starved) on the regulator and it was that sensitive run smooth or choke a little as Blues said more pedal more fuel will the pressure accommodate...

    @MercDeuceMan here's my setup...

    0_20180525_170622.jpg

    First start of the year...starts great put it in gear back out and as I get into light there fuel hitting the windshield like sprinkling rain and it was sunny out...smelt raw fuel shut it down...It was the loose clamp at the line in at the regulator...but the reg was fine...They are plastic and that sucks...like the fittings too, Plastic..:confused:

     
    Last edited: Jun 25, 2019
  9. sedantudor
    Joined: Jan 28, 2012
    Posts: 50

    sedantudor

    On my 47, I have to run an electric pump as well. the car has a hurst style engine mount and it blocks the location for the mechanical pump hence the need for an electric pump. I tried all kinds of fuel pumps from the $9.99 NAPA special to a 299.99 holley electric pump. I burnt them all up in about 6 to 8 months. To get to the original question about the pressure regulator, it is my experience that as fuel pump delivers fuel, it will reach the regulator and become restricted (obviously, that is what we are trying to achieve) causing a pressure drop to the carb(s) themselves. This seems to be especially true about electric pumps. even though this is what people are after it has a negative side effect of causing the pump to produce excess fuel and it will begin to back flow. Again, this seems to be a bigger problem with electric pumps. In my opinion the best way to solve the problem is to install a pressure regulator with a return line, even on a mechanical pump. it will send the excess fuel back to the tank and prevent the excess fuel not being used back logging in the fuel line which could also cause a potential leak. With an electric pump this can cause the pump to overheat and fail. As I said before I do not run a mechanical pump. I ended up using a holley pressure regulator that cost around 100.00 bucks. The summit part number is HLY-12-841. It uses NPT fittings instead of AN fittings which can be an issue to find if something happens to a fitting on the road. It is a return style pressure regulator. I have had it on the sedan for two years and no problems. Runs better than ever. I have not good experiences with the Mr. Gasket style fuel pressure regulator. I have had them break, leak, and spray fuel all over the place. The NAPA pump I ran was only putting out about 9 psi and a pressure regulator was required.
     
  10. flynstone
    Joined: Aug 14, 2005
    Posts: 1,594

    flynstone
    Member

    be aware, 3 diff brand name pumps stock otta the box 9 to 11 lbs, sucks had to put a regulator on two diff cars... I like what some one said use uor old spring in the new pump
     
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  11. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,536

    Blues4U
    Member
    from So Cal

    Just a line in and a line out. It works fine like that. A mechanical pump does not need a return line, it will only pump as much as it can and when the pressure at the pump outlet meets the limit it just won't pump any more until the pressure goes back down, which it will immediately as the carb consumes more fuel.

    I've considered adding a return line from the end of the fuel log, but really haven't felt the need to do that. As with most systems, simpler is better. If you don't need it, don't complicate things.
     
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  12. okiedokie
    Joined: Jul 5, 2005
    Posts: 3,524

    okiedokie
    Member
    from Ok

    Had one come apart on me also. Junk.
     
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  13. clem
    Joined: Dec 20, 2006
    Posts: 2,311

    clem
    Member

    between 9- 10psi...is that too much psi and if so the regulator suspect?

    Way to much ! Will give you the problems that you are getting.
    1&1/2 - 2&1/2 -max of 3 pounds pressure for these.
    I’ve had similar problems and ran a return line as in post 29
    Anything over 4 seems toooo much

    Two types of regulators available (from my experience) blocking and bi-pass.
    Most seem to be bi-pass.
     
    Last edited: Jun 25, 2019
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  14. clem
    Joined: Dec 20, 2006
    Posts: 2,311

    clem
    Member

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  15. Stogy
    Joined: Feb 10, 2007
    Posts: 12,177

    Stogy
    ALLIANCE MEMBER

    It's a 2010 build. Nothing lasts forever I thought there was something not working as well I think it's worth a swap in of the Holley or potentially other regulator...the carbs were rebuilt quite extensively 1 year ago and it seems sluggish and starting has been affected as well...did Edmund's make something? I'd like less plastic...at a minimum.
     
  16. Stogy
    Joined: Feb 10, 2007
    Posts: 12,177

    Stogy
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    That sounds really good...off part hunting real soon...thanks everyone. I will update on how it goes...
     
  17. Stogy
    Joined: Feb 10, 2007
    Posts: 12,177

    Stogy
    ALLIANCE MEMBER

    I think your talking fuel pumps...no matter the pump pressure wouldn't the regulator meter it?

    I wouldn't be surprised if it's just good ole O-rings...in air tools they wear out...nothing wrong with the rotating or static parts just a deteriorated O-ring...but plastic threads...not real good.
     
    Last edited: Jun 25, 2019
  18. Pete1
    Joined: Aug 23, 2004
    Posts: 1,630

    Pete1
    Member
    from Wa.

    That is the ONLY way a deadhead regulator will work properly.

    There are 2 types of regulators in common use.
    1 - Deadhead, which actually is a restrictor type.
    2 - Bypass, which requires a return line to the fuel source.

    On a modified engine, the supply line system from the tank needs to be big enough to supply the carbs or injectors enough fuel at FULL THROTTLE so the engine does not lean out.
    One method of checking this is a pressure gauge on the output side of the fuel block or regulator.
    THIS GAUGE NEEDS TO BE VISIBLE SAFELY WHILE DRIVING THE CAR AT SPEED!
    IT CAN NOT be mounted inside the car for safety reasons.
    If fuel pressure drops below recommended on a full power run through first gear, (which it will with a deadhead regulator) get rid of that regulator and install a bypass type.
    Another method of checking is an air/fuel ratio gauge. If you are leaning out at wide open throttle and going to bigger jets does not make a significant difference, you need bigger supply system.
    Have you ever wondered why those bypass regulators have 1/2 inch pipe threads in them?? It is for a reason.
    Many cars came from the factory with 1/4 inch fuel lines from the tank. These work ok for general street driving but not with a modified engine.
    If you have a fuel pump in the tank or mounted in the rear somewhere, the lines and pickups AHEAD of the pump (suction side) need to be larger than the pressurized ones after the pump.
    All of this information and why it works can be found at many places on the internet.
     
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  19. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 5,135

    Bandit Billy
    ALLIANCE MEMBER

    Can you tell the difference between these two regulators visually?
    upload_2019-6-25_21-59-9.png
    and this one
    upload_2019-6-25_22-0-5.png
    Look the same (same pic I'm pretty sure), one regulates down to 1 psi, the other only down to 4.5. I see a lot of people confuse the two. I reckon Holley could even tuck them in the wrong boxes on occasion.
    I run the latter on my flathead, gauge confirms 2 to 3 psi for my Stromberg 97s. I would not trust those round types too far. In fact, the tuner who worked on getting my blown flathead to run efficiently said if I had one of those on it he wouldn't work on the car. I don't know if he was referring to safety or performance or both, all I know is that I complied.
    upload_2019-6-25_22-8-8.png
    I tucked it behind the blower where it is less visible. Flex line to the firewall and hard lines to the carbs.
    upload_2019-6-25_22-9-58.png
    I did have to replace that moon fuel gauge with one that reads from 0 to 6 psi rather than this 16 psi so I could get an accurate measurement.
     
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  20. Boneyard51
    Joined: Dec 10, 2017
    Posts: 2,106

    Boneyard51
    Member

    The repair kit , Holley #12-807.is for both regulators. It shows a heavy and a light spring . Probably the only difference in the two regulators.





    Bones
     
  21. Stogy
    Joined: Feb 10, 2007
    Posts: 12,177

    Stogy
    ALLIANCE MEMBER

    When I saw fuel dripping off my carb and seeing 10psi after driving it I wasn't to comfortable with the Round Plasticy thing either...So I'm going to go shopping for one of those Holley and yeah it would be the one you and Blues are using...and perhaps a pressure gauge like you did...this is all helpful info...Thanks

    I wonder if that kind of pressure 9 -10 will damage the carbs? Its probably been going on for a while...but I haven't driven a lot this year...gotta get on it...:eek:
     
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  22. clem
    Joined: Dec 20, 2006
    Posts: 2,311

    clem
    Member

    You are correct. One has a blue dot of paint on it and one has a red dot.
     
  23. clem
    Joined: Dec 20, 2006
    Posts: 2,311

    clem
    Member

    From all the things I have read here on the Hamb, the Malpassi is the only one that has no negative comments.
    The cheap ($32) holleys seem to have 50% good comments, which means that 50% are not so good....
     
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  24. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,536

    Blues4U
    Member
    from So Cal

    The Malpassi's look great too. That would be what I went to next if I ever change this one out. Or the next car that needs one.
     
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  25. hemihotrod66
    Joined: May 5, 2019
    Posts: 29

    hemihotrod66

    Sounds to me like you have either a float or needle and seat issue...
     
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  26. Boneyard51
    Joined: Dec 10, 2017
    Posts: 2,106

    Boneyard51
    Member

    9 to 10 pounds of pressure won’t damage a carburetor permanently, but may make the needle and seat leak... at that pressure.....lower the pressure.... problem goes away....no damage.




    Bones
     
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  27. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 5,135

    Bandit Billy
    ALLIANCE MEMBER

    I would be surprised if there is any damage caused by a few extra psi. Before I added the 12-804 I was running 12-887 which is a bypass regulator (with return line to tank) to knock the high pressure TanksInc in-tank pump down to 4.5-9 psi direct to the 97s. I could not find a regulator at the time of the build that would take the huge psi pump down to 2-3psi for carb use.
    You can see it here on an early assembly photo on the rail.
    upload_2019-6-26_10-37-22.png
    The result was blowing gas past the check valves in the carbs creating a rich running condition. I left the return regulator as-is and routed the outlet into the 12-804 which all but cured the problem by reducing the pressure to 2-3 psi. A complicated fuel system to say the least as it turned out. Not sure if that helps or hinders but it is offered none the less.
     
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  28. Stogy
    Joined: Feb 10, 2007
    Posts: 12,177

    Stogy
    ALLIANCE MEMBER

    I am going to look into that, I need to do something...All this info is helpful...we are all a voice...

    Info brought forth here highlight the many things that can play a part in performance. Thanks
     
  29. clem
    Joined: Dec 20, 2006
    Posts: 2,311

    clem
    Member

    Exactly, caused by excessive pressure.
    The holley 94 doesn’t like more than 3-4 lbs max
     
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  30. alchemy
    Joined: Sep 27, 2002
    Posts: 13,857

    alchemy
    Member

    Can any of youse guys that have set up a return line on your systems with Strombergs show us how? Is it just another line from the splitting fuel line block (after the regulator) running back to the tank? Is it full size (maybe 5/16")? Are there any restrictors in it anywhere at all? Does it just dump straight into the top of the tank? How does it work and still keep 2 lbs of pressure to the carbs?
     
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