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

fuel pressure problem, help me out

  • Thread starter Thread starter slowhatch82
  • Start date Start date Feb 10, 2004

slowhatch82

Founding Member
Jun 11, 2002
583
0
0
NJ Pine Barrens
Feb 10, 2004
#1
  • Feb 10, 2004
  • #1
fuel pressure is 30psi when car is running, fuel pump primes, but when i shut it off it drops to 0 right away, isnt it supposed to hold pressure? is this the fuel pump/regulator or what?

also could this be the cause of my car struggling to go above 3500/4000?

thanks
chris
 

FceDncr

New Member
May 10, 1999
520
0
0
Izmir, Turkey
Feb 10, 2004
#2
  • Feb 10, 2004
  • #2
How are you able to read your fuel pressure? And yes, it should hold for at least awhile. You either have a bad FPR or fuel pump.
 
P

PRO50SC

New Member
Dec 28, 2003
1,012
1
0
Olney, Maryland
Feb 10, 2004
#3
  • Feb 10, 2004
  • #3
Notch Rocket said:
How are you able to read your fuel pressure? And yes, it should hold for at least awhile. You either have a bad FPR or fuel pump.
Click to expand...
What he said.
 

axeman

Founding Member
Feb 9, 2001
1,348
0
36
Elizabethtown, PA
Feb 10, 2004
#4
  • Feb 10, 2004
  • #4
it should hold pressure for a while and still have some pressure even hours later. something is definatly wrong. sorry, i'm not sure what it is though. i would think it would be either the fpr or pump. someone will know, just hold tight.
 

slowhatch82

Founding Member
Jun 11, 2002
583
0
0
NJ Pine Barrens
Feb 10, 2004
#5
  • Feb 10, 2004
  • #5
alright thanks, i know a few guys at the shop, they have a pressure gauge for testing fuel pressure...tires pressure, whatever...

so do you guys think my car cutting out upper rpms is related to this problem?
 

stangbear427

Active Member
Nov 11, 2002
2,401
1
49
New England
Feb 10, 2004
#6
  • Feb 10, 2004
  • #6
Yes, but your problem isn't that it doesn't hold when you shut it off- it's that you're starving for fuel. Stock fuel pressure is 38psi @ 0 vac. If you don't have an adjustable FPR, you need to get one and crank it up where it belongs before you screw your engine up. It could also be a bad pump that isn't supplying the fuel you need, but the moral is, you don't have enough pressure. At 3500+ rpm, you should have 40psi or more, depending on how much throttle you're giving it.
 

stangbear427

Active Member
Nov 11, 2002
2,401
1
49
New England
Feb 10, 2004
#7
  • Feb 10, 2004
  • #7
Woah! Just went to your webpage- which car are you talking about, the '88 or the '82? On a carburated engine, 30 psi is about twice what you should have- which would also give you serious drivability troubles.
 

slowhatch82

Founding Member
Jun 11, 2002
583
0
0
NJ Pine Barrens
Feb 11, 2004
#8
  • Feb 11, 2004
  • #8
the 88...i sold the 82 alittle while ago....man i miss that thing! it flew compared to the 88, but i guess once i get it running right with a few mods it'll be ok right

alright im gona get a adjustable fpr and try that out, if it doesnt work i guess ill be dropping the tank! fun stuff!

thanks guys
 
J

jerry beach

Founding Member
May 20, 2002
2,671
0
46
Ocala,FL
Feb 11, 2004
#9
  • Feb 11, 2004
  • #9
Fuel pressure should hold steady for 1 min. after the pump is turned off. Its highly likely you have a bad fuel pump check valve. I think its safe to say you need a new FP. Its no big deal, but the edges are very sharp so be careful. I just put in a BBK 155lph pump, and it would not sit in the hanger and bolt in place. The nipple on it was longer than stock. The easiest way to make it fit was cutting some of the hard line off on the factory hanger.

Do not run the car up to the point where it cuts out, cause lean is bad.
 

slowhatch82

Founding Member
Jun 11, 2002
583
0
0
NJ Pine Barrens
Feb 11, 2004
#10
  • Feb 11, 2004
  • #10
alrighty, ill stay away from it...thanks guys
 
You must log in or register to reply here.

Similar threads

D
Fuel Erratic Fuel Pressure 1985 GT
  • DienstXIV
  • Jan 14, 2026
  • Fox 5.0 Mustang Tech
Replies
16
Views
627
Fox 5.0 Mustang Tech Jan 16, 2026
AeroCoupe
C
98 gt fuel pressure issues
  • chasecollier1984
  • Jun 2, 2026
  • SN95 4.6L Mustang Tech
Replies
0
Views
31
SN95 4.6L Mustang Tech Jun 2, 2026
chasecollier1984
C
M
01 mustang 3.8 fuel pressure issue
  • Mhaley2006
  • May 29, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
61
1996 - 2004 SN95 Mustang -General/Talk- May 29, 2026
Mhaley2006
M
I
1994 Cobra - Fuel Pressure Drops Revving at Idle
  • IconicSilverGT500
  • Apr 11, 2026
  • 1994 - 1995 Specific Tech
Replies
16
Views
366
1994 - 1995 Specific Tech Apr 24, 2026
Mcmahst
F
2004 Mustang GT – Fuel Pump Not Priming
  • Fayio
  • Apr 22, 2026
  • SN95 4.6L Mustang Tech
Replies
7
Views
184
SN95 4.6L Mustang Tech Apr 27, 2026
n0v8or
N
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?