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

Electrical What would cause both, no spark and no fuel pressure? (Solution: PCM relay)

  • Thread starter Thread starter Foxslider
  • Start date Start date Sep 24, 2020
Prev
  • 1
  • 2
First Prev 2 of 2

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,949
10,587
203
polk county florida
Sep 28, 2020
#21
  • Sep 28, 2020
  • #21
So many times I've followed along on a thread where a member is having a problem and a test path is given, here in foxsliders case things were complicated by a wreck and the ensuing modifications done to the front sheetmetal and wiring. And to complicate things further a relocated battery. I'm putting my money on either the new distributor is malfunctioning (not unheard of) or a wiring issue.
I think it's this so maybe I'll do that cause I read someone had the same problem. Yeah, that will fix it! Look, if you think these cars are complicated you're in for a shock.
Take a break, then refocus on the issue.
 
Last edited: Sep 28, 2020
Reactions: Foxslider and 7991LXnSHO

Foxslider

im not that much of a idiot
Oct 25, 2019
543
156
53
Houston, TX
Sep 28, 2020
#22
  • Sep 28, 2020
  • #22
I tested most all that. I know they have nothing to with each other. But on this car, i think its a timing thing. It appears it was flooded. Had to be. It seems like a chain reaction thing. I assume more issues will rise.

Look at this EEC/PCM relay. They are 1 in the same right? Lol this thing is tuuhrashed! Gotta be it.

Also not the factory PCM relay since it has 5 prong. Factory was 4. Or this is not the PCM relay. Looks like it is and in right area.
 

Foxslider

im not that much of a idiot
Oct 25, 2019
543
156
53
Houston, TX
Sep 28, 2020
#23
  • Sep 28, 2020
  • #23
91GTstroked said:
Interesting. The previous owner put the battery in the truck, but I don't have a wire going back to the negative side of the battery. Wondering if I should add this?

Not trying to highjack your thread op.
Click to expand...

I mean if its running good/charging and no issues its probably not a issue. Just another ground. But it def. Shouldnt hurt to put it in.
 
Reactions: 91GTstroked

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
7,387
2,745
194
Kearney, NE
Sep 28, 2020
#24
  • Sep 28, 2020
  • #24
Where did you find that rusted relay? If it was under the driver’s seat most years, it should be the fuel pump relay. It does look like it was under water.
 

Foxslider

im not that much of a idiot
Oct 25, 2019
543
156
53
Houston, TX
Sep 28, 2020
#25
  • Sep 28, 2020
  • #25
Up by the computer. Once i pulled it. Has the same notch/look. Was hanging down, but above the computer, not attached to factory spot that is apparently hard to get to. Telling me someone has changed it before also. Got one coming in tomorrow.
 

Boostedpimp

20+ Year Stangneter
May 8, 2003
1,451
493
154
NJ
Sep 28, 2020
#26
  • Sep 28, 2020
  • #26
wow was that car in hurricane Katrina? are there any other signs of rust/corrosion to the wiring or electrical system?
 

Foxslider

im not that much of a idiot
Oct 25, 2019
543
156
53
Houston, TX
Sep 28, 2020
#27
  • Sep 28, 2020
  • #27
Might of been. Bought it from corpus christi area. Had grass and coming from under the wing on hatch everytime i wash it for last year. Lol im like how is this possible.

But at sametime, i dont see corrosion on a much other stuff. All the wiring looks to be in fair condition for being 30yrs old. Computer looks good. Very light bit of browning on top of plastic holder frame from heat.
 
N

NXcoupe

Active Member
Dec 3, 2009
80
27
28
Dayton, OH
Sep 28, 2020
#28
  • Sep 28, 2020
  • #28
Foxslider said:
Up by the computer. Once i pulled it. Has the same notch/look. Was hanging down, but above the computer, not attached to factory spot that is apparently hard to get to. Telling me someone has changed it before also. Got one coming in tomorrow.
Click to expand...
That is the eec relay then. And that does not look like it was working at all. Check the wiring and make sure they didn't rig it up to bypass the relay.
 
N

NXcoupe

Active Member
Dec 3, 2009
80
27
28
Dayton, OH
Sep 28, 2020
#29
  • Sep 28, 2020
  • #29
Foxslider said:
I mean if its running good/charging and no issues its probably not a issue. Just another ground. But it def. Shouldnt hurt to put it in.
Click to expand...
Incorrect. What happens most often when the ground is not connected to the battery is pin 46, signal return burns out and the vehicle is lucky if it runs. Also, this ground isn't for a light bulb or a relay, it's for electronics that are monitoring frequencies and very small voltage changes, which require a solid, clean ground. I have had to do this for customers that come in for a tune and after installing the ground back to the battery some of their drivability concerns go away.
 
Reactions: Foxslider

Foxslider

im not that much of a idiot
Oct 25, 2019
543
156
53
Houston, TX
Sep 28, 2020
#30
  • Sep 28, 2020
  • #30
Right on. Connector and wires attached look good.

I only said that about being ean to batt. b/c mine wasnt for a while didnt notice anything. But i still did it just to be correct.
 

91GTstroked

15 Year Member
Jun 14, 2007
504
282
93
Sep 28, 2020
#31
  • Sep 28, 2020
  • #31
NXcoupe said:
Incorrect. What happens most often when the ground is not connected to the battery is pin 46, signal return burns out and the vehicle is lucky if it runs. Also, this ground isn't for a light bulb or a relay, it's for electronics that are monitoring frequencies and very small voltage changes, which require a solid, clean ground. I have had to do this for customers that come in for a tune and after installing the ground back to the battery some of their drivability concerns go away.
Click to expand...

Where exactly am I running this ground wire from? One drivability problem I have is a slight hesitation while driving around town. Feels like a slight surge.
 

Boostedpimp

20+ Year Stangneter
May 8, 2003
1,451
493
154
NJ
Sep 29, 2020
#32
  • Sep 29, 2020
  • #32
 

Foxslider

im not that much of a idiot
Oct 25, 2019
543
156
53
Houston, TX
Sep 29, 2020
#33
  • Sep 29, 2020
  • #33
Well, its got spark now. And fuel. But not starting. When i was putting old dist. Back in, i forgot to check the location on the pointer thing on the rotor. Would that throw off timing? Or potentially make it "180" out? Lol.

FP still seems weak, when i depress shrader valve i just get minor drip, no squirt. But ill check that with a gage.
 

Foxslider

im not that much of a idiot
Oct 25, 2019
543
156
53
Houston, TX
Sep 29, 2020
#34
  • Sep 29, 2020
  • #34
Ya, i learned the rotor matters. lol. Got it up and running. Seems to have a miss, i must of base timed it to far advanced and quite close to running out of room CCW. But its up and running. Just a timing issue now. Preciate all the input.

edit: the miss was from a old fouled plug i put it instead of the good one by accident. I had grabbed that other plug to check socket size. Doh!

So running good now. Idles high now though about 1100 rpm. Hot start issue still persists. But thats just the CCA 1/0 wire not cutting it for the negative battery cable.
 
Last edited: Sep 29, 2020
Reactions: Potomus Pete
N

NXcoupe

Active Member
Dec 3, 2009
80
27
28
Dayton, OH
Oct 1, 2020
#35
  • Oct 1, 2020
  • #35
91GTstroked said:
Where exactly am I running this ground wire from? One drivability problem I have is a slight hesitation while driving around town. Feels like a slight surge.
Click to expand...
Where the battery used to sit, rearward of there, on the apron, there is a black wire screwed to the sheetmetal. It used to be connected to the battery through a pigtail. Cut this off and solder, don't crimp, a 10g wire to it and run it back to the battery. Then, disconnect battery for about 10 min and allow adaptives to reset. Then everything should work as designed.
 
Reactions: 91GTstroked
Prev
  • 1
  • 2
First Prev 2 of 2
You must log in or register to reply here.

Similar threads

K
Engine 2000 Mustang GT - Fuel issue post-blown spark plug repair
  • kenster1092
  • Feb 26, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
378
SN95 4.6L Mustang Tech Mar 10, 2026
kenster1092
K
B
'03 GT Fuel Pump/Pressure/Delivery Issue
  • Brodach
  • Oct 21, 2025
  • SN95 4.6L Mustang Tech
Replies
8
Views
924
SN95 4.6L Mustang Tech Oct 31, 2025
gkomo
Engine 1990 LX 5.0L EFI Mustang Fuel Management Problems - HELP!
  • 5.0LXStanger
  • May 25, 2025
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
45
Views
2K
Fox 5.0 Mustang Tech Jul 11, 2025
5.0LXStanger
1999 Mustang GT - No Start- Need help understanding the fuel pump circuit and how it works
  • 99gtGuy
  • Nov 4, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
1
Views
535
1996 - 2004 SN95 Mustang -General/Talk- Nov 7, 2025
04newedge-
0
D
Foxbody Misfire 5.0 Swap
  • DPORTER0729
  • May 2, 2025
  • Fox 5.0 Mustang Tech
Replies
7
Views
628
Fox 5.0 Mustang Tech Jul 13, 2025
90sickfox
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?