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

FUEL PUMP RELAY

  • Thread starter Thread starter 87fast
  • Start date Start date Jul 1, 2004
8

87fast

New Member
Dec 20, 2003
39
0
0
Jul 1, 2004
#1
  • Jul 1, 2004
  • #1
FUEL PUMP RELAY HELP

I HAVE A 87 LX 5.0 TODAY I TURNED THE CAR OFF AND THE FUEL PUMP KEEP RUNNING.I`M PRETTY SURE THE RELAY IS BAD HAVENT CHANGED IT YET HAD TO FIND LOCATION FIRST.TO TIRED TO CHANGE RIGHT KNOW AFTER I FOUND OUT WHERE IT WAS .MY QUESTION IS WHEN IM GOING DOWN THE ROAD AND HIT A BUMP THE CAR ACTS LIKE IT IS GOING TO STALL.
WILL THE RELAY CAUSE THE FUEL PUMP TO SHUT OFF AND COME BACK ON AND WILL A ONE OR TWO SECOND DROP IN FUEL PRESSURE CAUSE THIS.WHEN IT HAPPENS IT CAUSE`S THE CAR TO JERK PREETY HARD WHEN IT CATCHES BACK UP.THE FUEL PUMP IS ABOUT A YEAR OLD BUT NOT USED IN THE LAST 9 MONTHS HAD THE TOP OF THE MOTOR APART FOR MODS .THE PROBLEM WAS THERE BEFORE THE MODS BUT WENT AWAY AFTER WE SPRAYED THE TPS OFF WITH CONTACT CLEANER .
 
8

87fast

New Member
Dec 20, 2003
39
0
0
Jul 1, 2004
#2
  • Jul 1, 2004
  • #2
RELAY IS BAD TOOK OUT AND PUMP WENT QUIT RUNNING
 

ECU5.0

Banned
Jan 10, 2004
1,803
1
0
raleigh, nc
Jul 1, 2004
#3
  • Jul 1, 2004
  • #3
put a new relay in it....like 9 bucks from a parts store. dont know what to tell you about the other problem though
 
8

87fast

New Member
Dec 20, 2003
39
0
0
Jul 1, 2004
#4
  • Jul 1, 2004
  • #4
PUT NEW RELAY IN WENT DOWN THE ROAD AND SHUT OFF.RELAY IS HOT THINK PUMP IS GOING BAD .SOMEONE HELP
 
S

ss93cobra

Founding Member
Apr 10, 2002
1,422
1
0
Wilmington NC
Jul 1, 2004
#5
  • Jul 1, 2004
  • #5
The relay will get a little warm since it's under the drivers seat close to the exhaust. Anyway, your second post mentioned that you removed the relay and the car stopped running. That is what should have happened. As far as the electrical part, power goes from the relay to the fuel pump shut-off switch in the hatch cargo area (inside in front of the driver's side tail lamp) and then to the pump. As fas as the mechanical portion of this, have you checked the fuel filter or the fuel pressure? The stalling,jerking part could be caused by a plugged filter or a weak pump producing low pressure. Can you give more input on what you've done? When the car stalls out, can you hear the pump still running?
 
V

v8only

Active Member
Jul 3, 2003
2,378
22
49
Jul 1, 2004
#6
  • Jul 1, 2004
  • #6
turn the caps lock off, it's like you're yelling at us, and it's hard to read.
in an 87, the relay is under the drivers seat. Be sure that it is fastented to the floor board good, and that all wires are tight and very snug. In my brothers 86 gt, everytime he moves the seat around it tugs on one of the wires that sometimes causes it to kill.

If you have a problem that happens when you hit bumps in the road, that sounds to me like a loose or faulty connection. Check the wiring all the way out to the gas tank, and check all grounds. It may be a bitch to find, but that is where I would start at least.

I have had my ignition switch (that I put the key into) go bad, and when that does, it won't supply any power to the fuel pump, so that's something to think about too.
 
R

ratrapp

New Member
Apr 24, 2004
510
0
0
buena vista,va
Jul 1, 2004
#7
  • Jul 1, 2004
  • #7
my stang did the same thing so my nobrainer test was simple.with my car running i got out and kicked the gas tank a couple of times and the fuel pump would cut off and start up again.bad fuel pump.also it wouldn't hurt to replace the inertia switch(fuel pump kill switch)as they seem to fail at the worst times and they aren't very expensive.
 
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
700
Fox 5.0 Mustang Tech May 3, 2026
Shakerhood
U
No fuel pump relay in harness
  • Uli661
  • May 18, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
4
Views
105
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jun 1, 2026
Uli661
U
A
1987 5.0 speed density Foxbody crank no start
  • Alan2204
  • May 23, 2026
  • Fox 5.0 Mustang Tech
Replies
10
Views
150
Fox 5.0 Mustang Tech May 30, 2026
Mcmahst
New fuel pump relay
  • Scrapla347
  • Nov 3, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
12
Views
783
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Nov 8, 2025
Scrapla347
D
Fox 88 foxbody no power to red and black wire at fuel pump relay
  • drod88
  • Dec 1, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
7
Views
302
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Dec 2, 2025
Mcmahst
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?