Fuel Pressure Question - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



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

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 06-05-2005, 08:28 PM
jdhoggg's Avatar
New Member
 
Last photo:
Join Date: May 2005
Location: asheboro, nc
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Fuel Pressure Question

I have a problem with the fuel pressure on my car. At idle it sits at 8psi, but when I accelerate at WOT it drops slowly to zero and the car starts popping....detonation obviously. I don't have a rising rate fuel pressure regulator on the car and I think I might just be able to turn up the pressure at idle to accomodate the fuel demand at WOT. I am just wondering if turning the pressure up like this will adversely affect anything.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-05-2005, 08:33 PM
Bumpstick's Avatar
Hammer and a torch
 
Last photo:
Join Date: May 2003
Location: Southeast TX
Age: 54
Posts: 1,258
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Sounds like either the reg or the pump is bad...? Thats the purpose of a regulator to keep up with demand at a given or set pressure...
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-05-2005, 11:37 PM
aka Duke of URL
 
Last wiki edit: Finding vacuum leaks Last photo:
Join Date: Oct 2001
Location: Rockville, MD
Posts: 4,821
Wiki Edits: 1

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by jdhoggg

At idle it sits at 8psi, but when I accelerate at WOT it drops slowly to zero and the car starts popping....detonation obviously.

I think I might just be able to turn up the pressure at idle to accomodate the fuel demand at WOT. I am just wondering if turning the pressure up like this will adversely affect anything.
8PSI is enough. Much more and you stand the chance of blowing the needle off the seat and flooding the carburetor. It sounds like a bad pump or some type of restriction. Is this an electric or mechanical fuel pump?

Fresh fuel filter(s)? If electric, installed below fuel level so as to prime pump so it doesn't have to pull and push fuel?

Describe your installation more clearly.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-06-2005, 05:21 AM
jdhoggg's Avatar
New Member
 
Last photo:
Join Date: May 2005
Location: asheboro, nc
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The pump is a mechanical Edelbrock pump (110 gph) and it's brand new. I have a new, inline filter in place as well that's supposed to flow 390 gph. The regulator is one of those Summit billet jobbies. My pressure line is tapped into the side of the regulator and I have an outside mounted Pro Comp fuel pressure gauge I'm getting all these readings from. Think I'll need to probably work my way from the filter in since it is connected by a SS hard line to the pump?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-06-2005, 06:30 AM
aka Duke of URL
 
Last wiki edit: Finding vacuum leaks Last photo:
Join Date: Oct 2001
Location: Rockville, MD
Posts: 4,821
Wiki Edits: 1

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by jdhoggg

The pump is a mechanical Edelbrock pump (110 gph) and it's brand new. I have a new, inline filter in place as well that's supposed to flow 390 gph. The regulator is one of those Summit billet jobbies. My pressure line is tapped into the side of the regulator and I have an outside mounted Pro Comp fuel pressure gauge I'm getting all these readings from. Think I'll need to probably work my way from the filter in since it is connected by a SS hard line to the pump?
Quote:
Performer RPM Street Fuel Pumps

Designed for use with all Edelbrock carburetors, these high-performance Street Fuel Pumps have six valves and a flow capacity of 110 GPH. The unique valve design improves flow quantity and quality, and will support engines up to 550 hp. High-volume, 3/8" NPT inlet and outlet surpasses the capacity of conventional models. Produces 6 psi which is correct fuel pressure for street. For gasoline or mixed fuels only.
The fuel pump you have has an internal fuel pressure regulator. What is the purpose of the external regulator? Can you give me SUMMIT's PN? Is it designed for an electric pump?

Why not try bypassing the regulator and see if she will hold pressure?

If not the regulator, there must be an air leak downstream, such as a cracked rubber hose section. You then need to isolate (and cap off) the various sections of the supply line and check to make sure it holds a vacuum. Is your tank vent operable?

How much HP are you making? Engine and carb type?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-06-2005, 07:08 AM
my alter ego
 
Last photo:
Join Date: May 2005
Location: little kansas
Posts: 100
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Do you have a fuel cell and 3/8 or 1/2" line? or do you have a stock tank and stock line?
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-06-2005, 02:17 PM
jdhoggg's Avatar
New Member
 
Last photo:
Join Date: May 2005
Location: asheboro, nc
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Kultulz,
I don't have the original box for the part # but I did try to locate it in my cataolg and found that the regulator was offered with an ELECTRIC pump in a combo deal. (I was not advised that the pump I purchased had in internal regulator when I bought it and the regulator.) I will try to bypass it and post how things went. As far as HP goes, I haven't dyno'd the car yet so I'm not sure. It's a 355 with torquerII manifold, 600cfm edelbrock carb, mild cam, light port job on iron heads, msd 6al ignition, and a 175 shot of gas; HP estimates when it doesn't pop and sputter and run like a POS?...LOL
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-06-2005, 02:18 PM
jdhoggg's Avatar
New Member
 
Last photo:
Join Date: May 2005
Location: asheboro, nc
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I have a stock tank but have a 1/2 inch line.....
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 06-06-2005, 04:05 PM
71 c-10's Avatar
just a kid and his truck
 
Last photo:
Join Date: Sep 2003
Location: VA
Age: 27
Posts: 351
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
what fuel pump do you have, a buddy of mine is having nightmares with fuel delivery on his 383 monte, the edel race pump puts to much pressure at idle and hte street pump falls away while driving, i think , but he also has an external regulator and maybe that is his problem, good luck and i look foward to busting my shop teachers balls if that fixes it :-D
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 06-06-2005, 04:19 PM
my alter ego
 
Last photo:
Join Date: May 2005
Location: little kansas
Posts: 100
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
How is your 1/2" line ran into the tank?
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 06-06-2005, 07:38 PM
Member
 

Last journal entry: frame build
Last photo:
Join Date: Apr 2005
Location: sioux falls, sd
Age: 68
Posts: 601
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Try tapping a vacuum gauge in as close to the tank as you can, but definetly between the tank and pump. Get out and check the readings at idle, cruise and WOT or If you put a long line on it you can do this from the front seat
Increasing readings indicate a restriction in the pickup or upstream lines. A steady reading would indicate a filter problem. Fluctuating readings indicate a pump problem..
A similar problem encountered was caused by a little flap of rubber on the inside of a fuel line
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 06-07-2005, 05:49 AM
jdhoggg's Avatar
New Member
 
Last photo:
Join Date: May 2005
Location: asheboro, nc
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The pump is a street pump. I bypassed the fuel pressure regulator yesterday evening and am letting the teflon paste I used on the pipe threads for the fuel pressure gauge set up today. Will try it this evening to see if the problem persists.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 06-07-2005, 05:52 AM
jdhoggg's Avatar
New Member
 
Last photo:
Join Date: May 2005
Location: asheboro, nc
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
61, if bypassing the fpr doesn't do the trick, then I'll work it using your suggestion.......makes sense to me.....thanks for the suggestions.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 06-10-2005, 08:29 PM
jdhoggg's Avatar
New Member
 
Last photo:
Join Date: May 2005
Location: asheboro, nc
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Bypassed the fpr and still had the up and down readings.....I called edelbrock and they have agreed to swap the pump out with me. I'll be removing it and sending it to them sometime soon....thanks for the suggestions guys.
Reply With Quote Quick reply to this message

Recent Engine 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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




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
Fabricating intake manifold. gemini86 Engine 25 10-02-2009 01:10 PM
Why does fuel pressure drops when electric fan turns on Palmtrees57chevy Engine 34 03-31-2005 11:47 PM
Fuel Pressure gauge question Jag Daddy Engine 4 09-27-2004 05:07 PM
34 Ford fuel tank question 302 Z28 General Rodding Tech 1 02-01-2004 04:55 PM
Fuel Pressure Variance slomotion Engine 2 04-02-2002 01:25 PM


All times are GMT -6. The time now is 10:47 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.