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

Fuel 91 fox low fuel pressure issues

  • Thread starter Thread starter Slygh93
  • Start date Start date Apr 15, 2018
  • Tags Tags
    foxbody fuel pressure

Slygh93

Member
Apr 15, 2018
20
4
13
Delaware
Apr 15, 2018
#1
  • Apr 15, 2018
  • #1
Hey there, long time reader/ searcher of the forum. Just never actually posted. But anywho i have a 91 fox that i purchased recently. It has a trick flow intake manifold, a bbk cold air intake/mass air flow/ 70mm throttle body, 24# injectors, under drive pullies and a few other things i cant think of off the top of my head. When i purchased the car the performance was a little lackluster for the mods it had. The gas tank leaked a little so pulled it and while it was out i put a new edlbrock 155lph fuel pump. Car ran great for a few days and now it stumbles pretty bad at idle and while im driving unless i really step on it. The car has a adjustable fuel pressure regulator(looks pretty old) and when i adjusted it in either direction i saw no change in fuel pressure. Am i right to assume the afpr is bad? Car currently is only getting 20psi of fuel pressure upon startup and drops to about 10 before stalling out
 

mikestang63

SN Certified Technician
Aug 27, 2012
11,606
8,859
214
In the garage
Apr 15, 2018
#2
  • Apr 15, 2018
  • #2
pull the vacuum hose of the FPR and smell it. If it is wet or smells like gas then it is bad. You are running very lean. You should be at 37 to 41 with the hose off and plugged while the car is idling. You could also have screwed up in the fuel pump install and either kinked the hose of the sock is on wrong or clocked, or the pump is bad out of the box.
 
Reactions: Scott7512
You must log in or register to reply here.

Similar threads

M
01 mustang 3.8 fuel pressure issue
  • Mhaley2006
  • May 29, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
84
1996 - 2004 SN95 Mustang -General/Talk- May 29, 2026
Mhaley2006
M
Engine Hiccup at full throttle
  • keel
  • Jun 2, 2026
  • Fox 5.0 Mustang Tech
  • 2
Replies
30
Views
398
Fox 5.0 Mustang Tech Jun 10, 2026
Noobz347
C
98 gt fuel pressure issues
  • chasecollier1984
  • Jun 2, 2026
  • SN95 4.6L Mustang Tech
Replies
0
Views
38
SN95 4.6L Mustang Tech Jun 2, 2026
chasecollier1984
C
I
1994 Cobra - Fuel Pressure Drops Revving at Idle
  • IconicSilverGT500
  • Apr 11, 2026
  • 1994 - 1995 Specific Tech
Replies
16
Views
374
1994 - 1995 Specific Tech Apr 24, 2026
Mcmahst
1
Engine 91 mustang 302 Low acceleration car backfires pops and acts like it doesn’t want to take fuel
  • 1991Fox5.0
  • Oct 4, 2025
  • Fox 5.0 Mustang Tech
Replies
16
Views
956
Fox 5.0 Mustang Tech Oct 6, 2025
1991Fox5.0
1
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?