• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech

possible bad fuel pump??

  • Thread starter Thread starter smilts
  • Start date Start date Jun 18, 2011

smilts

Member
Jun 18, 2011
104
0
16
Roaring Springs Tx
Jun 18, 2011
#1
  • Jun 18, 2011
  • #1
Ive been having trouble lately with my 94 GT not wanting to run after a litte bit of driving. Finaly I decided to check fuel pressure after, replacing EGR and EGR posistion sensor. Readings were odd and not overly helpfully to me. KOEO I had around 15PSI. At idle I had 34psi. with mild throttle it dropped down to around 32psi. And dropped to 30psi with a bit more throttle. I'm thinking it needs a new fuel pump. Unless I misunderstand shouldnt the pressure go up a few pounds with load instead of down? When we were starting the car. It didnt seem to smoothly move up the pressure it started at 5psi then yanked up to 10psi and so on untill landing at 34 at idle as well. The fuel filter is about three days old.
 

toyman

10 Year Member
Jul 19, 2007
1,944
54
79
Vernon BC
Jun 18, 2011
#2
  • Jun 18, 2011
  • #2
What I don't understand here is how the fuel pressure can be higher at KOER than KOEO. Yes the pressure should rise with load not fall. Before replacing the FP remove the vacuum line to the FPR. If you can smell or see gas in that line then the problem is most likely a FPR problem.
 

smilts

Member
Jun 18, 2011
104
0
16
Roaring Springs Tx
Jun 19, 2011
#3
  • Jun 19, 2011
  • #3
Ok we did remove tvac line and there was no gas visable but i will smell of it tomorrow to double chck and with the vac line off pressure went up to 37psi KOER.
 

toyman

10 Year Member
Jul 19, 2007
1,944
54
79
Vernon BC
Jun 19, 2011
#4
  • Jun 19, 2011
  • #4
smilts said:
Ok we did remove tvac line and there was no gas visable but i will smell of it tomorrow to double chck and with the vac line off pressure went up to 37psi KOER.
Click to expand...

That's where it should be. You should also see the same reading KOEO (i.e. same as no vacuum). There should be no smell of gas. Any trace indicates a leaking diaphragm in the FPR.
 

smilts

Member
Jun 18, 2011
104
0
16
Roaring Springs Tx
Jun 19, 2011
#5
  • Jun 19, 2011
  • #5
Ill just replace both the fuel pump and the FPR. Are concern was that the problem gets worse when the car has been running for a bit, especialy in the heat. I kinda thought it might be a weak fuel pump getting worse the longer it was running. Thank you for your advice.
 

KamiKaziDK

Member
May 16, 2005
555
0
17
Mesa, Az
Jun 19, 2011
#6
  • Jun 19, 2011
  • #6
It's your fuel pump, not your regulator. I just had a 255 die on me like that, idled great, but when I stomped on it, it would drop to under 30 and hate life. I have a full sweep gauge, so it was easy for me to test it under load.
 
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
4
Views
206
1996 - 2004 SN95 Mustang -General/Talk- Yesterday at 2:52 PM
JohnKay
J
C
98 gt fuel pressure issues
  • chasecollier1984
  • Jun 2, 2026
  • SN95 4.6L Mustang Tech
Replies
0
Views
94
SN95 4.6L Mustang Tech Jun 2, 2026
chasecollier1984
C
B
'03 GT Fuel Pump/Pressure/Delivery Issue
  • Brodach
  • Oct 21, 2025
  • SN95 4.6L Mustang Tech
Replies
8
Views
926
SN95 4.6L Mustang Tech Oct 31, 2025
gkomo
K
Engine 2000 Mustang GT - Fuel issue post-blown spark plug repair
  • kenster1092
  • Feb 26, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
380
SN95 4.6L Mustang Tech Mar 10, 2026
kenster1092
K
S
Fuel ‘88 GT Runs Rich Cold — Fixes Itself When I Unplug Sensors (ECT, MAF, O2, etc.)
  • Sufarry
  • Nov 6, 2025
  • Fox 5.0 Mustang Tech
Replies
12
Views
883
Fox 5.0 Mustang Tech Nov 9, 2025
Mustang5L5
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific 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?