Blackbird

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!

SJH

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

Blackbird

[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!

Pro Stock John

iTrader: (34)

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.

Reckless

iTrader: (9)

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.

Blackbird

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.

XLR8NSS

iTrader: (4)

[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">

cablebandit

iTrader: (37)

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

LS1derfull

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" />

Blackbird

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