Notices
Forced Induction Superchargers | Turbochargers | Intercoolers

Fuel Pressure Dropping - Your Opinions why and how to solve

 
Old 03-11-2002, 04:00 PM
  #1  
TECH Addict
Thread Starter
 
Join Date: Nov 2001
Location: Bellevue, Wa
Posts: 2,650
Likes: 0
Received 0 Likes on 0 Posts
Default Fuel Pressure Dropping - Your Opinions why and how to solve

ok, had this problem from day 1. since I am getting serious with the setup I need to solve it.

my base fp for some reason is 64psi (no biggie). but... when I go wot it will drop all the way down to 50 before climbing again thanks to the fmu. if there was no fmu it would sit at 50 or less.

does the problem lie in the fuel pump(s) or regulator? or other?

I have the stock intank and a inline provided by ATI.

I was thinking it was regulator and was going to try to add an external regulator in hopes it could maintain FP. I inquired about a regulator from a vendor and they suggested it's the fuel pump and the regulator won't help. this comment put a seed of doubt in my mind that my adding an external regulator would solve my problem.

Any of you guys that have gone thru your fuel system woes wanna share your thoughts?

Thanks!
Blackbird is offline  
Old 03-11-2002, 05:17 PM
  #2  
SJH
TECH Regular
 
Join Date: Feb 2002
Location: the moon
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Fuel Pressure Dropping - Your Opinions why and how to solve

the stock regulator should be fine and not cause that.
I have mine externally mounted at the rail and modded to work with a vacuum/boost signal and it workls perfectly.
It's also fully adjustable FYI(at least the 98's are).
The problem lies not in the regulator but where it is mounted.
It's 20 feet back from the rail in the stock config and that's why you see a pressure drop way up at the rail when you really tax the system hard.
If pressure does build when the fmu kicks in then you are not out of pump and it is just the poor location of the pressure regulator.
Got my car back in action this weekend by the way <img src="gr_stretch.gif" border="0">
Steve- aka "just me","Just_Me","Another Just me",etc etc,lol
SJH is offline  
Old 03-11-2002, 05:26 PM
  #3  
TECH Addict
Thread Starter
 
Join Date: Nov 2001
Location: Bellevue, Wa
Posts: 2,650
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Fuel Pressure Dropping - Your Opinions why and how to solve

[quote] Got my car back in action this weekend by the way
<hr></blockquote>

Sweet! <img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" />

Sent you an email btw. If you get a sec please reply.

Thanks!
Blackbird is offline  
Old 03-11-2002, 09:18 PM
  #4  
LS1Tech Co-Founder
iTrader: (34)
 
Pro Stock John's Avatar
 
Join Date: Nov 2001
Location: Chicago, IL
Posts: 42,517
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Fuel Pressure Dropping - Your Opinions why and how to solve

Mine would do that, only it would go as low as 35 after a few weeks.

I installed a 255lph intank and it never goes below 55.
Pro Stock John is offline  
Old 03-12-2002, 01:05 PM
  #5  
Super Moderator
iTrader: (9)
 
Reckless's Avatar
 
Join Date: Nov 2001
Location: Canton, GA
Posts: 10,000
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Fuel Pressure Dropping - Your Opinions why and how to solve

A regulator will not help if your pump is inadequate. Sounds like your lines and/or pump are not adequate for the volume required. That is, the pump can not keep up with the demand.
Reckless is offline  
Old 03-12-2002, 01:34 PM
  #6  
TECH Addict
Thread Starter
 
Join Date: Nov 2001
Location: Bellevue, Wa
Posts: 2,650
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Fuel Pressure Dropping - Your Opinions why and how to solve

problem I have with that assumption is the fact it drops as soon as I hit the gas. Don't even have to get into boost to make FP drop. 1/2 throttle and it drops a good 6 points. I certainly don't have much of a demand for fuel at that point. Also if it was not enough pump FP would not be able to rise when the fmu kicks in I do believe.
Blackbird is offline  
Old 03-12-2002, 06:55 PM
  #7  
Adkoonerstrator
iTrader: (4)
 
XLR8NSS's Avatar
 
Join Date: Nov 2001
Location: Deep in the seedy underworld of Koonerville
Posts: 21,420
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Fuel Pressure Dropping - Your Opinions why and how to solve

[quote]Originally posted by Blackbird:
<strong>problem I have with that assumption is the fact it drops as soon as I hit the gas. Don't even have to get into boost to make FP drop. 1/2 throttle and it drops a good 6 points. I certainly don't have much of a demand for fuel at that point. Also if it was not enough pump FP would not be able to rise when the fmu kicks in I do believe.</strong><hr></blockquote>

I would definately check your inline pump to make sure it is running and getting full voltage. I have experienced this same problem your describing and it was the inline pump. CHECK IT! <img src="gr_images/icons/wink.gif" border="0"> <img src="gr_tounge.gif" border="0"> <img src="gr_grin.gif" border="0">
XLR8NSS is offline  
Old 03-12-2002, 07:06 PM
  #8  
9 Second Club
iTrader: (37)
 
cablebandit's Avatar
 
Join Date: Nov 2001
Location: Cleveland, OH
Posts: 7,911
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Fuel Pressure Dropping - Your Opinions why and how to solve

I had that problem with the stock regulator. I added a better regulator...plumbed in the return line between the axle and the tank. I left the stock regulator in the tank in case my external regulator ever fails. Mine now holds 58-60 psi
cablebandit is offline  
Old 03-14-2002, 09:07 PM
  #9  
TECH Addict
 
LS1derfull's Avatar
 
Join Date: Dec 2001
Location: new england
Posts: 2,298
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Fuel Pressure Dropping - Your Opinions why and how to solve

Hey all you blower guys, factory wiring gauge is very thin to fuel pump, you could increase pump performance running heavier gauge wiring to stock pump.This would really pay off when highest pump demands are needed. Good luck <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
LS1derfull is offline  
Old 03-15-2002, 01:31 AM
  #10  
TECH Addict
Thread Starter
 
Join Date: Nov 2001
Location: Bellevue, Wa
Posts: 2,650
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Fuel Pressure Dropping - Your Opinions why and how to solve

I have heard of people doing this.
I may just do that when I crawl under there next.
Blackbird is offline  
 


Thread Tools
Search this Thread
Quick Reply: Fuel Pressure Dropping - Your Opinions why and how to solve


About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: