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

Fuel pump never shuts down..?

  • Thread starter Thread starter 4000 Pounds of Iron
  • Start date Start date Apr 21, 2004

4000 Pounds of Iron

Founding Member
Nov 6, 1999
473
0
0
Nashville, TN
Apr 21, 2004
#1
  • Apr 21, 2004
  • #1
OK, to make matters brief, I have a 1991 Crown Vic police car that I transplanted a 1988 Mustang 5.0 HO/T5 drivetrain into. It's all stock SD for now, but I'm having trouble getting the final details together, so I figured I'd ask the experts. Look at http://www.crownvic.net/ubbthreads/postlist.php?Cat=&Board=UBB24 for details in the Vast 4k#Fe HO/T5 Swap Chronicle.

Problem #1: The fuel pump begins running as soon as the battery cable is connected, and does not shut down, ever. Is there a pressure switch of some kind that tells it when to turn off? On the other hand, it shouldn't be running at all when the key is off, and it is. When I remove power to the EEC by pulling its relay out, it shuts off. I have checked the fuel pump relay and swapped it with the AC relay and it's fine.

Problem #2: What under the hood sounds like an electric jigsaw? Whenever my clutch pedal touches the floorpan, I get a sound like that from under the hood. Since there are no switches of any kind on my custom pedal setup, I assume I'm somehow grounding something with the pedal.

Problem #3: What are the rest of the electrical connectors used for on the T5 relative to the AOD? I connected the two neutral safety switch wires, so they're out of the way, but there are other wires in the connector that I don't know about, besides the VSS on the tailshaft. Help?

Hope you all can help. If it makes any difference, my EEC is listed for a 5.0 HO TBird and not a Mustang, if anyone has a spare SD EEC lying around that they will sell cheap, please send me an Email.

 

Attachments

  • getfile.php?id=118765&toggle=fullsize&f=newsig.webp
    14.1 KB · Views: 116

4000 Pounds of Iron

Founding Member
Nov 6, 1999
473
0
0
Nashville, TN
Apr 22, 2004
#2
  • Apr 22, 2004
  • #2
TTFT Helllo?

ECHO


Echo


echo
 
K

kevin2m4

New Member
Mar 16, 2004
50
0
0
Barrie Ontario Canada
Apr 22, 2004
#3
  • Apr 22, 2004
  • #3
the fuel pump is running all the time because the fuel pump relay is fudged.
mine did the same thing. it should be 3 noxes on the driver side fender. one is the a/c relay one is the fpr relayt and one is egr?
replace them all they ar 5$ each new
if that doesnt do it try the ignition switch. its under the steering coloumb shroud and there are 2 screws that have no screw tips. you need pliers to get them out

im not positive but sd eec's that will work and maintain your cruis control are LSC ecu';s and mark 7
thunderbirds had ho's in em too
 

4000 Pounds of Iron

Founding Member
Nov 6, 1999
473
0
0
Nashville, TN
Apr 22, 2004
#4
  • Apr 22, 2004
  • #4
I have checked the fuel pump relay and swapped it with the AC relay and it's fine
Click to expand...

Not the relay, The Tbird EEC turned out to be fried, because the pump acted normal when I threw the 160-horse CV comp back in.

Still looking for the jigsaw...

4k#Fe
 
You must log in or register to reply here.

Similar threads

Engine Fuel not pumping
  • Creomod
  • Apr 13, 2026
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
43
Views
708
Fox 5.0 Mustang Tech May 3, 2026
Shakerhood
J
Fuel Fuel pump does not prime
  • justadude07
  • May 26, 2025
  • Fox 5.0 Mustang Tech
Replies
10
Views
470
Fox 5.0 Mustang Tech May 26, 2025
justadude07
J
F
2004 Mustang GT – Fuel Pump Not Priming
  • Fayio
  • Apr 22, 2026
  • SN95 4.6L Mustang Tech
Replies
7
Views
188
SN95 4.6L Mustang Tech Apr 27, 2026
n0v8or
N
1
Electrical 1985 mustang gt Led conversion trouble
  • 1985fox
  • Jan 5, 2026
  • Fox 5.0 Mustang Tech
Replies
10
Views
541
Fox 5.0 Mustang Tech Jan 15, 2026
1985fox
1
D
89 foxbody fuel pump not priming
  • Dubsantana
  • Jul 6, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
5
Views
466
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jul 12, 2025
AeroCoupe
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?