Holley billet fuel pressure regulator issue. - Page 2 - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans Advertise
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Hotrodding Basics
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #16 (permalink)  
Old 05-14-2019, 05:03 AM
55 Tony's Avatar
Registered User
 
Join Date: Nov 2018
Location: Cocke County, TN
Posts: 1,306
Wiki Edits: 0

Thanks: 174
Thanked 218 Times in 192 Posts
My q-jet needs more than 3 psi for the 1/8 mile at WOT. Maybe because it only has one needle and seat. It is a high flow needle and seat but with only 3 psi it will run out of fuel.

    Advertisement
__________________
Young enough to learn ... too old to remember.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #17 (permalink)  
Old 05-14-2019, 11:42 AM
Registered User
 
Join Date: May 2008
Location: ohio
Posts: 3,800
Wiki Edits: 0

Thanks: 310
Thanked 558 Times in 470 Posts
Yeah I know 3 psi won't work but I have to unhook to see how much pump is actually putting out but I have some other things wrong with it now that I have to figure out what the heck it is and it is somewhere in the ignition and I think my MSD box is going junk as its only at low rpm I am having the issues I am experiencing. I will have to get back to the fuel regulator part as soon as I swap out my ignition box. If its not one thing its another.
Reply With Quote Quick reply to this message
  #18 (permalink)  
Old 05-15-2019, 03:18 AM
BigMo's Avatar
Registered User
 
Join Date: Dec 2012
Location: Tennessee, near Smokey Mtns.
Posts: 396
Wiki Edits: 0

Thanks: 15
Thanked 41 Times in 41 Posts
Quote:
Originally Posted by TommyK View Post
Holley says that regulator is to be used with electric fuel pumps only.


Sent from my SM-G900V using Tapatalk
Reply With Quote Quick reply to this message
 
  #19 (permalink)  
Old 05-15-2019, 03:18 AM
BigMo's Avatar
Registered User
 
Join Date: Dec 2012
Location: Tennessee, near Smokey Mtns.
Posts: 396
Wiki Edits: 0

Thanks: 15
Thanked 41 Times in 41 Posts
Bad gauge

Sent from my SM-G900V using Tapatalk
Reply With Quote Quick reply to this message
  #20 (permalink)  
Old 05-15-2019, 03:21 AM
BigMo's Avatar
Registered User
 
Join Date: Dec 2012
Location: Tennessee, near Smokey Mtns.
Posts: 396
Wiki Edits: 0

Thanks: 15
Thanked 41 Times in 41 Posts
Line restriction.....bypass line big enough?

Sent from my SM-G900V using Tapatalk
Reply With Quote Quick reply to this message
  #21 (permalink)  
Old 05-15-2019, 07:08 AM
Registered User
 
Join Date: May 2008
Location: ohio
Posts: 3,800
Wiki Edits: 0

Thanks: 310
Thanked 558 Times in 470 Posts
The gauge is good and I don't care what holley says about the regulator being for a electric pump only a regulator is a regulator and they all work the same. my fuel line is not restricted and is 5/16 and runs straight back then to my tank.

My fuel lines are as about as straight as you can get. They go like a L shape. Straight from the pump and a slight angle bend to go to the tank but its not a sharp bend as I know that would cause a slight smack in the wall of the fuel line. And just to show the regulator can be used for electric fuel pumps or mechanical it works just the same with either.

I had my truck started up yesterday just for a few minutes checking a few things other then it and the pressure was up to almost 5 psi so I don't know yet what can be going on but I bought me a new sending unit to use as the one i have is the original of the truck and someone told me that had an issue like this once and here the main line hose on the sending unit developed a tiny hole in it and wen the fuel level got low enough it would cause some issues of loosing fuel pressure cause of air getting into the line but i don't know.

I am going to check some other things but I got a few other possible ignition related issues that just surfaced as well that I need to fix as well.There is no reason this should not work. Other makers of regulators of return line style don't state for electric pumps only. They all work the same as an obstruction to the flow. I even unhooked my return line and the pressure did not change any.

I will post after I get some more things ironed out.
Reply With Quote Quick reply to this message
  #22 (permalink)  
Old 05-15-2019, 10:40 AM
Registered User
 
Join Date: Apr 2007
Posts: 13,131
Wiki Edits: 0

Thanks: 337
Thanked 1,394 Times in 1,094 Posts
Regulators like very thing else have limits. A bypass regulator meant for use on EFI pumps come is basically 2 ranges these being:

- Factory and aftermarket low pressure TBI which will control inputs of 20 to 30 psi down to delivery of 10 to 15 psi.

- High pressure factory and aftermarket port injection and aftermarket high pressure TBI which controls inputs of 70 to 90 PSI to delivery pressure of 40 to 50 psi.

Operating these with a low pressure mechanical pump meant for a carburetor of 3 to 7 psi is likely under the control range ratio of input to output pressures.

In the case of a mechanical pump on the engine a simpler non bypass regulator can be used as these are in the pressure range of the pump output of less than 10 psi to the carb's input of 3 to 5 psi. If there is a bypass it is usually a fixed bleed intended to keep fuel flowing at idle and low speeds to prevent vapor lock. Vapor lock happens when the pump maintains a constant low pressure on the intake side that is below the fuel's vapor pressure which results in the fuel vaporizing in the supply line.

I'm not a big fan of the factory engine driver pump for several reasons:

- It's on the wrong side of the system which results in pulling fuel from a lengthy line which lowers pressure in that line that is a cause of vapor lock. It also exposes lowered pressure fuel to G forces in competition that significantly alter fuel delivery rates to the pump thus at the carb.

- Pump output in terms of pressure and volume is variable with engine speed. For stock pumps this often is insufficient at high speed resulting in a drop in pressure and volume at a point where more of both is needed, this is the cause of a lot of top end lean out that far too many tuners try to solve by increasing carb jet size. At the other end racing pumps deliver too much fuel at idle and low speed. This increases the pressure drop on the feed side line enhancing vapor lock problems thus needing a bypass to keep fuel moving so as to reduce this problem. This also enhances the vapor lock issues in the feed line as these pumps are pulling harder on the feed line further depressing pressure on that side, certainly a larger line helps by reducing the restriction to flow presented by the line but that is of little consequence at idle and low speeds.

So I much prefer on the street and occasional racer an electric in or outside near the tank with a bypassing regulator. This offers a constant pressure and volume which exceeds the maximum need that is controlled below that point by regulation. This keeps higher pressures on the feed line that are above the vapor pressure of the fuel so vapor lock is essentially eliminated. The excess pressure and volume keeps the G forces from causing starvation problems on the delivery end.

Bogie
Reply With Quote Quick reply to this message
The Following User Says Thank You to BogiesAnnex1 For This Useful Post:
36 sedan (05-15-2019)
  #23 (permalink)  
Old 05-15-2019, 02:22 PM
36 sedan's Avatar
Registered User
 
Join Date: Apr 2016
Location: American Canyon, CA
Posts: 1,117
Wiki Edits: 0

Thanks: 661
Thanked 324 Times in 259 Posts
It is not my intent offend anyone in any way, however, I would like to iterate a little more on Boggieannex1's excellent article above. Specifically on carburetor inlet pressures, as high inlet pressure is the #1 most common cause of carburetor tuning problems.

A little basics:
Carburetors are siphon based fuel dispersement devises. They are designed to operate on internal combustion engines using the vacuum created by the motor through venturi, as air flows through the carburetors throttle body. During this action, fuel is pulled from the bottom of the carburetor’s float bowls by the venturi based vacuum siphoning fuel through a restriction devise (aka jet) and mixed into the carburetor’s air stream. The float bowls supply the fuel and the float bowls are VENTED, they are under NO pressure other than atmospheric and the added weight of the fuel itself that is held in the float bowl (simplified basic explanation of carburetor’s operation).

Carburetors (unlike fuel injection) do not operate under pressure. The fuel supply to a carburetor only needs to fill and maintain the float bowl(s). Most carburetor’s normal inlet operating pressure is 3 - 5psi (pounds per square inch). Some manufactures will spec a maximum 6-7psi (slightly higher for some), often this maximum psi is misinterpreted as the desired inlet operating pressure. The MAXIMUM pressure is NOT the carburetor’s recommended inlet operating pressure. It is the maximum the manufacture’s design of their carburetor’s needle and seat (valve that shuts off fuel to float bowl) can withstand before possible failure (not being able to shut off completely). The carburetor should ALWAYS be operated at less inlet pressure than the recommended MAXIMUM. PERIOD.

The fuel pump for a carburetor only requires enough pressure to overcome lift (rise of the fuel line) and acceleration forces to push fuel into the float bowl in sufficient enough quantities to satisfy the motor’s needs at all demands, usually this is calculated at WOT (wide open throttle) in GPH (gallons per hour). Could a higher pressure pump increase the pump’s output capacity? This is where people get into trouble with carburetors, the answer is NO. A higher pressure pump of a certain capacity (GPH) can NOT supply any more fuel than the equal capacity (GPH) lower pressure pump. It’s apples and oranges.

Increasing the carburetors inlet pressure beyond the recommended normal inlet pressure will not only NOT help your carburetor’s performance, it can actually be detrimental to its performance. In a best case scenario the added pressure will only cause a richer than desired mixture by forcing too much fuel into the bowl (like setting float level too high), which in turn can cause numerous tuning and operating woes. However in a worst case scenario it can actually cause damage to the motor and even a fire by flooding raw fuel past the bowl vents into and on top of the motor.

PLEASE follow the manufacture’s recommendations, learn and understand how your carburetor works, so your motor will run its very best. Safely.
Reply With Quote Quick reply to this message
  #24 (permalink)  
Old 05-15-2019, 05:12 PM
Registered User
 
Join Date: Jun 2012
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Quote:
Originally Posted by chasracer View Post
Let's not forget that 90+% of this is made off-shore now. WE are Quality Control now, not the manufacturers so it could be just a bad pump. I would pull it and send it back for a replacement.
Good advice. I tried an electric Holley pump some years ago. Only got 5 lbs max. Replaced it and it pumped 6.5 lbs as advertised.
Reply With Quote Quick reply to this message
  #25 (permalink)  
Old 05-15-2019, 06:06 PM
Registered User
 
Join Date: Sep 2015
Posts: 60
Wiki Edits: 0

Thanks: 6
Thanked 15 Times in 15 Posts
Just a quick description as I understand mechanical pumps. On mechanical pumps the pressure comes from the spring in the pump. All the push rod does is move the diaphragm against the spring, this is the suction stroke. When the diaphragm is pushed by the spring this is the discharge stroke.


Now for pumps in general, the pressure rating of a pump is the difference between the suction and discharge, not just the discharge Pressure. For example lets say a pump is rated for 6 psi. If a discharge pressure reads 3 psi the suction pressure has to be -3 for a total difference of 6 psi. A mechanical pump on the engine has to suck gas from the tank. If there is a restriction in the suction line (clogged suction filter, sludge in the line, clogged line in tank) or just the friction from the gas through the line the suction pressure will be less than atmospheric (negative pressure) the pressure gauge on the discharge will read less that the rated pressure of the pump. The suction side will usually be less than atmospheric on a mechanical pump as it has to draw the gas through the line from the tank and the pump probably is not lower that the tank to give it a positive pressure.


If you are still having trouble with the mechanical pump disconnect the suction line and blow it out with compressed air all the way back to the tank. If it is clogged in the tank this might give you some temporary relief. If this is the case you will have to clean the tank.


If the suction line is around any heat source you could have vapor lock.


This all I can think of for now!
Reply With Quote Quick reply to this message
  #26 (permalink)  
Old 05-16-2019, 07:48 AM
Registered User
 
Join Date: May 2008
Location: ohio
Posts: 3,800
Wiki Edits: 0

Thanks: 310
Thanked 558 Times in 470 Posts
I took my sending unit out to check it over before I even hooked up my line and looked into my tank and it was about as clean as it can get. There was no debris of any kind and even my fuel looked clean. The gas tank is only 5 years old which I know does not mean anything but it was clean inside and there is no restriction in my line at all but I got a new sending unit to throw in just to replace my old one and so at least I can say its all been replaced.

I will have to get to my fuel pump and unhook it from the regulator and see what it says on my gauge without the pressure regulator. I have to get to my ignition box first and would have it installed by now but as my bad luck would have it it was missing the hardware kit which includes the wire hookup that goes under my distributor cap to hookup my box to the magnetic pickup coil so I have to go to summit this Sunday and replace my box then get it hooked up and then see what my other issue is then back to my fuel pressure situation.

Something is going on somewhere as in low speed driving its not smooth and there is a constant sputtering then once you get the rpms up to a higher speed its fine and it was not like that a month ago so I know it can't be carb related as I tried adjusting some things on it and there was no change as it was already set good anyways. I checked my timing and its fine and has not changed and I checked my coil and it checks out still good so it has to be my MSD box as there is nothing else except plug wires which I am replacing but they are not very old at all only about 5 years old but I have a better set to put on just need to cut to length which I have not done before so I am having my Dad show me the ropes on that one this coming Sunday as well.

Will update once I have changed things and see what my pressure does.
Reply With Quote Quick reply to this message
  #27 (permalink)  
Old 05-16-2019, 05:52 PM
BigMo's Avatar
Registered User
 
Join Date: Dec 2012
Location: Tennessee, near Smokey Mtns.
Posts: 396
Wiki Edits: 0

Thanks: 15
Thanked 41 Times in 41 Posts
Regulators do have specific pressure ranges...but i have spec'd out fuel systems before by getting the pump, reg, lines, filters, etc all from various manufacturers w no regard for high pressure or low pressure needs. They seem to be interchangable. I have had issues w not going large enough on the return line and causing restriction and heating the fuel and pump up more than necessary. On a "street" style mech fuel pump a reg is prob overkill unless its a "race" version that is rated to 7-10 psi which will blow the needle out of the seat. I have a mech NASCAR type pump on one of my cars w a reg set at 6-6.5 psi and its good. But im running -8an lines for the volume. Pressure is just to keep the fuel moving under hard accel w a carb set up

Sent from my SM-G900V using Tapatalk
Reply With Quote Quick reply to this message
  #28 (permalink)  
Old 05-22-2019, 07:52 AM
Registered User
 
Join Date: May 2008
Location: ohio
Posts: 3,800
Wiki Edits: 0

Thanks: 310
Thanked 558 Times in 470 Posts
Just to update everyone I unhooked my mechanical pump from the regulator and it still has only 3 psi just like mentioned and this is the first time I have ever had a mechanical pump put out so little pressure as most of the ones I have gotten put out about 6 psi at the most and when the needle is pumping up and down on the gauge as the pump is working it goes from 2 to 6 psi.

On start up it will show it bouncing up and down from 2 to 5 psi then after a while it steadies at 3 psi. My previous pump was a different carter pump number I got a m4685 and it says 7 psi max on summit which is not always correct but this pump should pump out more then that. The one I had on my old engine was a m6624 and it always had higher pressure then the 4685 so I will be swapping them out and see if that is the fix for just enough pressure without it being just 3 psi but on the other hand I did take it for a drive yesterday after I changed out my wires to test drive and got on it to wide open throttle for at least a decent 1/8 mile romp and no issues what so ever under load of any signs of fuel starvation.

But I will be swapping it out anyway just to see after I get some other things in order.
Reply With Quote Quick reply to this message
  #29 (permalink)  
Old 05-22-2019, 10:25 AM
Registered User
 
Join Date: Apr 2007
Posts: 13,131
Wiki Edits: 0

Thanks: 337
Thanked 1,394 Times in 1,094 Posts
Quote:
Originally Posted by eric32 View Post
I took my sending unit out to check it over before I even hooked up my line and looked into my tank and it was about as clean as it can get. There was no debris of any kind and even my fuel looked clean. The gas tank is only 5 years old which I know does not mean anything but it was clean inside and there is no restriction in my line at all but I got a new sending unit to throw in just to replace my old one and so at least I can say its all been replaced.

I will have to get to my fuel pump and unhook it from the regulator and see what it says on my gauge without the pressure regulator. I have to get to my ignition box first and would have it installed by now but as my bad luck would have it it was missing the hardware kit which includes the wire hookup that goes under my distributor cap to hookup my box to the magnetic pickup coil so I have to go to summit this Sunday and replace my box then get it hooked up and then see what my other issue is then back to my fuel pressure situation.

Something is going on somewhere as in low speed driving its not smooth and there is a constant sputtering then once you get the rpms up to a higher speed its fine and it was not like that a month ago so I know it can't be carb related as I tried adjusting some things on it and there was no change as it was already set good anyways. I checked my timing and its fine and has not changed and I checked my coil and it checks out still good so it has to be my MSD box as there is nothing else except plug wires which I am replacing but they are not very old at all only about 5 years old but I have a better set to put on just need to cut to length which I have not done before so I am having my Dad show me the ropes on that one this coming Sunday as well.

Will update once I have changed things and see what my pressure does.
MSD boxes demand a lot of top end engine grounds, especially from the SBC and its gooped up head bolts. Each head and the intake should all be wired together from bolt/fastener positions that do not require sealer, only conductive grease to protect the joint from corrosion. This should then go to a good bonded chassis ground or back to the battey's negative terminal.

The MSD generates a very powerful output that is in the form of a square wave. This is very hard to mediate on the ground side via fasteners with sealer and head lubrication. The unresolved ground side currents from the spark plugs will seek ground and if that is insufficient through the fasteners it will go back through the electronics in the distributor and the MSD box. At the minimum it interfers with signal generation, at the extreme the smokes the electronics.

Since the amperage is low this doesn't require a starter sized ground cable, I find a number 10 wire to be sufficient that connects each head, the intake and possibly the distributor then leads off to ground at the chassis or battery. The connections need to be well bonded electrically so that means no paint, sealer or antiseize on the contacting surfaces, conductive electrical grease may be used, however.

The chances that the existing electronic components have sustained damage is high and replacement may be necessary.

Bogie
Reply With Quote Quick reply to this message
  #30 (permalink)  
Old 05-22-2019, 10:55 AM
BigMo's Avatar
Registered User
 
Join Date: Dec 2012
Location: Tennessee, near Smokey Mtns.
Posts: 396
Wiki Edits: 0

Thanks: 15
Thanked 41 Times in 41 Posts
Sounds like pump isnt workin rite. You should dead head at least 5 psi and steady. Get a good pump on there....hi performance carter or similar

Sent from my SM-G900V using Tapatalk
Reply With Quote Quick reply to this message

Recent Hotrodding Basics posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Insurance
Please select your insurance company (Optional)

Log-in



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fuel pressure regulator not lowering pressure stanley9875 Engine 19 05-18-2017 12:26 AM
400sbc tbi help 59 f-100 Engine 12 08-30-2014 08:53 AM
How much fuel pressure for a Holley 650? 4speed57 Engine 3 04-24-2011 04:42 PM
Holley fuel pump, return line or not to return line??? JD's camaro Engine 1 07-16-2010 05:17 PM
Holley 12-803 fuel pressure regulator conversion to a bypass type? kyyx Engine 3 02-14-2010 07:29 AM


All times are GMT -6. The time now is 04:59 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.