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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

wot fuel pressure

  • Thread starter Thread starter jake2582
  • Start date Start date Nov 28, 2007

jake2582

New Member
Jan 8, 2007
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tallapoosa
Nov 28, 2007
#1
  • Nov 28, 2007
  • #1
what do you guys maintain for fuel pressure at full throttle?
 

Vipersix

Founding Member
Feb 25, 2001
434
0
0
Clarksville, TN
Nov 28, 2007
#2
  • Nov 28, 2007
  • #2
Pressure at WOT shouldn't be an issue unless you are running a motor under boost. The purpose behind a fuel pressure regulator is to adjust the pressure for manifold pressure/vacuum. If you set the initial pressure at 45 psi then it will attempt to maintain that pressure differential at all settings.

i.e. If manifold pressure is zero then rail pressure is 45. If manifold pressure goes up to 10 psi then rail pressure will increase to 55 psi to overcome the increase.

For most engines, +/- 40 psi is sufficient.
 

PUNISHER RACING

Active Member
Aug 27, 2007
1,124
0
36
FORD CITY, PA.
Nov 28, 2007
#3
  • Nov 28, 2007
  • #3
8 psi
 

jake2582

New Member
Jan 8, 2007
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tallapoosa
Nov 28, 2007
#4
  • Nov 28, 2007
  • #4
i am asking because fuel pressure is correct with hose un hooked (40)ish...
under full throttle it drops to 30. i am wondering if the filter is stoped up or if the pump cant keep up? do you think the injectors are using more than the pump can pump?
 

Vipersix

Founding Member
Feb 25, 2001
434
0
0
Clarksville, TN
Nov 28, 2007
#5
  • Nov 28, 2007
  • #5
Unless you're experiencing a 10psi vacuum under WOT you're likely having a supply issue. How is your fuel system set up?
 

jake2582

New Member
Jan 8, 2007
107
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tallapoosa
Nov 28, 2007
#6
  • Nov 28, 2007
  • #6
Vipersix said:
Unless you're experiencing a 10psi vacuum under WOT you're likely having a supply issue. How is your fuel system set up?
Click to expand...

thanks for the help.
STOCK!
maybe a 255 pump? that should fix it right?
 

Vipersix

Founding Member
Feb 25, 2001
434
0
0
Clarksville, TN
Nov 28, 2007
#7
  • Nov 28, 2007
  • #7
What are you trying to feed? A mostly stock motor with up to around 36 lb injectors can normally be fed just fine with the stock fuel system. You may be experiencing pump failure or some other problem.
 

jake2582

New Member
Jan 8, 2007
107
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0
tallapoosa
Nov 28, 2007
#8
  • Nov 28, 2007
  • #8
maybe 350hp max.h/c/i 302cid 24lb injectors 6000rpm
wot fuel pressure=30lb 40lb when i whatck the throttle no load
i guess i will change the fuel filter tomorrow if it dont fix it i guess i will go for the pump
 

Vipersix

Founding Member
Feb 25, 2001
434
0
0
Clarksville, TN
Nov 30, 2007
#9
  • Nov 30, 2007
  • #9
Somewhere in the neighborhood of 380 hp is the max power output for 24 lb injectors but this would be running at 100%, a big no-no. 350 horses is pushing 24 lb injectors, you may want to also think about bumping up to a bigger injector or higher pressure.

I would bet that your pump is not enjoying the high workload caused by a higher than normal duty cycle experienced by your injectors. A bigger pump will definitely not hurt, plus it will allow you to bump up the fuel pressure from 36 psi to 40 psi so you won't be needing larger injectors right away.
 
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