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

I Got CEL code 543

  • Thread starter Thread starter Slow5.0
  • Start date Start date Apr 11, 2004

Slow5.0

Active Member
Feb 13, 2003
2,554
0
46
Portland, OR
Apr 11, 2004
#1
  • Apr 11, 2004
  • #1
Yesterday I was on the track racing little bit , and this morning when I turn on engine ,after 2 min car start shaking in neutral and in any gears , than I shut off engine and after 30min start engine again and engine run fine , than I take ride and sometime after 20 min engine start shaking again so I stoped car in AutoZone and those guys check engine light , they come up with code 543 ( Fuel Pump circuit open ; Battery to PCM )
I check every fuse's no blown fuses , fuel pressure is fine , 39psi like before ,I have adjustable FP regulator and 4 months old Walbro 255 HP fuel pump, I have no idea whats wrong , and what that mean Fuel Pump circuit open ; Battery to PCM , meybe no power or what
 

VibrantRedGT

"STANGNET'S PENGUIN SMACKER"
15 Year Member
Nov 29, 1999
14,679
424
154
Boca Raton, Florida
Apr 11, 2004
#2
  • Apr 11, 2004
  • #2
What I've seen about that 543 is a mystery. If the circuit is open all the time it would never shut off even the car was off. I got that code shortly after I installed the blower. If you run the fuel tank real low or dry this code will pop up.
 

Slow5.0

Active Member
Feb 13, 2003
2,554
0
46
Portland, OR
Apr 11, 2004
#3
  • Apr 11, 2004
  • #3
Sometime I run the fuel tank low but I have never have this problem before , I drive little bit tonight , sometime car run fine sometime it's shaking, sometime if I rev up a few time realy high that ting shut off I have no idea , meybe the FUEL PUMP RELAY is bad , and that relay in in CCRM , box over the fan, meybe that bad
Anybody else
 

Slow5.0

Active Member
Feb 13, 2003
2,554
0
46
Portland, OR
Apr 12, 2004
#4
  • Apr 12, 2004
  • #4
Guys , I need help right away , I need to fixed this , please help me out
 

Slow5.0

Active Member
Feb 13, 2003
2,554
0
46
Portland, OR
Apr 12, 2004
#5
  • Apr 12, 2004
  • #5
Nope code 543 is bad code , it's gone now , problem is something else and it's big problem, I talk with my mechanic and he told me I have ignition problems , So this whole Monday I tryin fing out whats wrong , this is what I check out and everything is fine ; spark plugs, spark plug wires, ingition module , distributor cap, rotor , fuel pump works fine , I have spare ECU computer and CCRM so I try swap them but nothing , I have no idea whats wrong but car run like **** and too frickin rich , spark plugs are wet , I find little bit fuel on them, meybe distributor or distributor gear is bad but when I start engine ,whole engine is shaking ,than sometime stop shaking than again shake again it's like in one hour engine run 25% good and 75% bad ,
Tomorrow I gonna take car to my friend and mechanic , meybe he can find out whats wrong , I don't wanna spend $84.13 for diagnostic check engine at Ford dealer
 

OrangeMustangGt

Founding Member
Mar 7, 2002
1,976
0
36
Cape Cod, MA
Apr 12, 2004
#6
  • Apr 12, 2004
  • #6
my car has always had that code, strange, never trips the light though. Since iv e owned the for 2 years, it has always idled like it has a cam, wonder if that is the problem? it seems to run ok though (although i have nothing to compare it to) i just wrote it off as a car problem that is normal. Now you got me interested. I dunno, ive checked the fuel pump, its new, mew fuel filter....what is the pcm to fuel pump circuit mean? what could this be doing?
 

Slow5.0

Active Member
Feb 13, 2003
2,554
0
46
Portland, OR
Apr 13, 2004
#7
  • Apr 13, 2004
  • #7
This morning I check ECT , IAC , MAF , air filter, all plugs and wires, rotor and distributer cap , ingition coil and module , everything is fine , now I have to check timing, dirstibuter gear and fuel filter
I was thinkin , night before I fing this problem I fill up full tank of gas , what I have some wather in the gas , metbe that cause my problem
 

Slow5.0

Active Member
Feb 13, 2003
2,554
0
46
Portland, OR
Apr 14, 2004
#8
  • Apr 14, 2004
  • #8
Today I toke a car to mechanic and he told me timing is good 14* like always and he told me cilynder #8 doesn't work and that could be , wire , spark plug, injector, power to injector or something in head, so Tonight I take off upper intake and I find little bit oil inside , but thats normal in ours cars, I checked all injectors and power to injectors , all if fine , I take off every spark plug every is kinda wet , looks like oil come intake or fuel ???, so I change plug on cilynder #8 , I clean PVC valve upper intake too , put verything together and change fuel filter and start a car , SAME THING like before
I don't know what to do next
 
H

HRT11

New Member
Feb 2, 2004
122
0
0
Plattsburgh, NY
Apr 14, 2004
#9
  • Apr 14, 2004
  • #9
dude i had the same thing a week or so ago!!!
im a freakin ford tech and cant figure it out! 543 doesnt make sense
hastn come back on yet-so id say dont worry about it
 

Slow5.0

Active Member
Feb 13, 2003
2,554
0
46
Portland, OR
Apr 14, 2004
#10
  • Apr 14, 2004
  • #10
Dude code 543 is wild code or what ever you call, it's gone now , my problem isn't that , read little bit
 
R

rockin_rick

Member
Oct 9, 2003
968
1
17
Jun 25, 2004
#11
  • Jun 25, 2004
  • #11
Figure this out yet?

Rick
 

Slow5.0

Active Member
Feb 13, 2003
2,554
0
46
Portland, OR
Jun 25, 2004
#12
  • Jun 25, 2004
  • #12
Yes i'm , that code is erorr , and I have busted valve springs keepers , but I fixed that a few months ago
 
You must log in or register to reply here.

Similar threads

T
Help with a 95 5L crank no start
  • TheBubbaJoe
  • Nov 4, 2025
  • 1994 - 1995 Specific Tech
Replies
3
Views
482
1994 - 1995 Specific Tech Nov 5, 2025
AeroCoupe
A
P0036 P0056 P0137 P0157 2020 Ford Mustang GT
  • AmkoA
  • Jun 16, 2026
  • 2024+ (S650) Mustang -General/Talk
Replies
0
Views
170
2024+ (S650) Mustang -General/Talk Jun 16, 2026
AmkoA
A
L
2003 mustang v6 3.8 fuel issue
  • lacole1
  • Jul 20, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
3
Views
115
1996 - 2004 SN95 Mustang -General/Talk- Jul 26, 2026
apple99Mustangdude
A
F
2004 Mustang GT – Fuel Pump Not Priming
  • Fayio
  • Apr 22, 2026
  • SN95 4.6L Mustang Tech
Replies
7
Views
368
SN95 4.6L Mustang Tech Apr 27, 2026
n0v8or
N
Electrical Issues with my 2006 mustang gt
  • VerneVdV
  • May 22, 2026
  • 2005 - 2009 Specific Tech
Replies
0
Views
139
2005 - 2009 Specific Tech May 22, 2026
VerneVdV
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?