How To Choose A Regulator for Carbureted Vehicles
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- Опубликовано: 10 фев 2025
- Choosing the correct Fuel pressure regulator won’t raise your blood pressure if you know
what to look for!
When choosing a fuel pressure regulator for your ride, you need to take into consideration
several factors. The regulator is a critical piece and should to be matched to the type of fuel
delivery system and the fuel pump that you are using or plan to use. This video will help
explain fuel pressure regulators that were designed for use with a carburetor.
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Finally after so much research I found someone that knows what the hell they're doing
Glad Holley finally taking a active roll on videos.
Keepem coming!
Larry
Ww+++!!!!!a!!
And nothing for those of us who know how these systems work, but want more information about _which_ Holley regulator would work for us best.
Despite this video and their site, Holley *still* doesn't offer a no-nonsense comparison table of all their Holley, AEM, and QFT regulators. It would make the job of picking one out so much easier.
Wish yall talked on turbo regulators
I bought the Holley Red pump rated for 7 psi for my sbc 350 with a Holley 4150 650 CFM. Had the issue where the pump would keep pumping fuel all the way through the carb and flood it. Sound like some a deadhead regulator could handle or should I be safe and run a return line?
(DECEMBER 2022) The 12-803 regulator that comes with the Blue Fuel Pump is defective. Tons of people complain about it. Will you replace it for just the regulator??
I have a question. In a return style system..What is the difference in using a deadhead regulator post carb vs a bypass regulator post carb? In my head its doing the same thing but for 1/4 the price
Great video, very informative. Thanks!
Could you recommend a fpr for a TBI gen1 chevy 4.3 v6 that needs 13psi?
Thanks for your video
Killed it on the video, yeah he was reading, .... but very well. I hope you sell a lot of Holley!
Hi, I would like to replace the original low pressure vacuum fuel pump for an in-line electric fuel pump on my outboard in order to deliver fuel from the tank to the high-pressure pump-evaporator, which fuel pressure regulator could be used between my fuel tank and my high-pressure pump-evaporator?
The low pressure pump must operate between 2 and 4 psi of pressure.
This will eliminate prime the fuel manually and avoid to buy an expensive low pressure vacuum fuel pump OE replacement part.
I am guessing this does work with a in the block fuel pump
when mounting a bypass regulator down stream of carb inlet plugging the outlet side of regulator is not an issue?
I bought a Holley bypass regulator. If the pressure is reduced on the “OUT” side of the regulator, and it’s connected AFTER the carb, how is the pressure reduced at the carb if regulator is after carb??
If you were to uncap your fuel line coming from the pump, and let if flow into a bucket, you would have ZERO fuel pressure in the line. There is no restriction, hence no pressure. The regulator after the carb creates an obstruction in the fuel circuit, just enough to set the pressure at 6psi, or whatever you have it set to, and the rest of the pressure that is over 6psi or whatever you have the regulator set to goes through the regulator and goes back to the tank. The bypass reg simply creates enough of a restriction to allow 6psi to build in the line, and lets the rest escape to the tank
I am definitely not an expert but I assume it is because it's a complete circuit. The resistance to flow at any point limits the entire system.
@@justinjburk I get it now, it reduces pressure through entire circuit, versus just after the circuit
Hope you can help I changed from mechanical to inline electric my trouble is the engine starts and runs for about 15 to 30 seconds then hesitates then stops. starting an hour later.the truck is chev 305 with spectra premium pump.does it sound like it needs a regulator.
Beginner Beginner I am having the same thing on a my mustang.
I just switched from mechanical to efi on my c10. Having some trouble getting the pressure to adjust on my setup. Got a bypass pressure regulator and no matter what I adjust the pressure still reads 0psi.
What is the rule of thumb as to the size of the 'Return' Line vs the 'Feed' Line? I feel it's time to move on from my current DeadHead set up and plumb a return.
That’s a very helpful video thanks.
I have a 770 Avenger. carb and the 12-803 regulator. Is there a benefit to running one outlet of the regulator to the primary fuel bowl and the 2nd outlet to the secondary? I currently have one outlet of the regulator feeding both fuel bowls with the 2nd outlet blocked off.
Why does the Holley 12-803 regulator state in the instructions not to use it with a mechanical fuel pump
Cannot find this fuel system selection chart on your webside. Maybe someone read this and help out.
I already have a regulator for my carburetor, I need a fuel gauge that bolts on to the regulator to see when get to 3 psi that I need
So, buy a -4 AN fitting, and a hose, and connect it to the pressure port on the regulator.
Could the dead head set up cause dieseling?
It should limit deiseling if it is set correctly. Too much pressure can be part of what causes deiseling.
No, a deadhead regulator will not cause dieseling.
Sheesh.. would be nice if all these great questions could be answered. @Holley
Hi there, at the 4"45" mark you show a QFT 4 Port Bypass regulator ( Claimed ) but I cannot find a QFT Bypass regulator like this . Do you have a part number for QFT 4 Port Bypass regulator. Thank you.
Zooming in it says 12-885 and it's pretty easy finding it off those numbers
So when your fuel pressure gauge goes from 5 down to zero that means the electric fuel pump isn't any good yes or no but yet I have plenty enough gas going to the carburetor
Can a bypass regulator's return line be tapped into the fuel line before the pump? Instead of going all the way back to the tank?
No
Which bypass regulator is recommended for 6 pack setup?
What a good supply pump with a built in reliable regulator and 1/2 inch inlet outlets to about 4-9psi for waste veg oil in a diesel vehicle please? Its protecting as well as supplying fuel to an expensive pump so the set up needs to be good.
I just bought the by-pass regulator #12-881 and hooked it up just like the instructions say to and I cant get the pressure down the gauge goes to max pressure even backing the adjuster all the way out, I am using holley blue pump my dead head regulator did not do this at least I can adjust it, I have switched the return line with fuel supply and it goes to zero pressure or max still cant adjust it maybe I have the wrong regulator for my carb and pump?
Give our tech line a call at 866-464-6553! -Keith
What regulator is recommended on a mechanical pump with a vent on the pump itself? (Chevrolet)
give our tech line a call for a recommendation! 866-464-6553
Why a bypass regulator after carb ? Will a regular regulator work??
Bypass regulators tend to be the most accurate and most capable. A non-bypass regulator can only handle so much flow and pressure.
HolleyPerformance thanks
A bypass regulator doesn't heat the fuel as much as a deadhead regulator does also. With a deadhead, the pump is constantly pressing all of it's output psi against the fuel that is backed up against the regulator, and the fuel is getting hotter. With a bypass regulator, the pump is only working against the 6psi or whatever you have the regulator set to, and the rest of the fuel is sent back to the tank to cool off. Cool fuel=more power, and less detonation issues.
My bypass regulator has an IN, an R (return), and an OUT. Yet your diagram shows only 2 ports being used! What is going on here?
"In" comes from tank sump, "Out" goes to carb, and "Return" goes back to tank ABOVE the fuel level.
These regulators nowadays are junk , just got 2 Holley regulators and both were defective
Question: do you put filter after the Regulator or before.
The filter should be before the regulator. -Keith
Car manufacturers have switched to returnless systems because the bypass system was heating the fuel and increasing the vapor in the evap system. Now this guy is saying the opposite??
Car manufacturers have switched to returnless because the pumps direct output pressure is now controlled by the ECU. No need for a return anymore.
I don’t understand how it’s possible to put the regulator after the carb. I thought the whole point of the regulator was to decrease the pressure going into the carb?
Kinda like a posi-trac in a plymouth. "just does"
You have to remember that fuel is a liquid that is incompressible (hydraulic). Therefore using a regulator that is set at say 12 psi max after the carb would mean that even the fuel log pressure will be the same pressure regardless. The best way to let the know the fuel pressure is to use a dash mounted fuel pressure gauge.
A wide open fuel line would have ZERO pressure when flowing into a bucket. Put a 6psi restriction anywhere in the line, and the pressure will be 6psi everywhere in the line. The regulator after the carb holds the pressure at 6psi, and lets the rest of the fuel flow, that would cause a higher pressure, back to the tank. Think of a return system as an organised leak, that self adjusts to limit the pressure to a preset limit. If your garden hose attached to a lawn sprinkler is holding 30psi of water pressure, and suddenly a pinhole appears, the pressure in the hose everywhere will be lower because of the water leaking out of the pinhole. Your carb would be at the end of the garden hose, and the "pinhole" in the hose is the return line that goes back to your tank. The regulator would be the pinhole that automatically adjusts the size of the pinhole to keep the pressure constant with regards to flow.
@@davelowets fantastic explanation thank you
@@yeboscrebo4451 👌