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

89 L.X. 5.0 gas gauge always points full even with Key out

  • Thread starter Thread starter revedup
  • Start date Start date Jul 31, 2006

revedup

Member
Nov 18, 2005
63
0
6
S.F. Cal,
Jul 31, 2006
#1
  • Jul 31, 2006
  • #1
can ANYONE TELL ME HOW TO TROUBLESHOOT THIS FULL GAS GAUGE READING ALL THE TIME??????
iTS GOT 212,00 MILES AND I BELIEVE ITS ORIGINAL SENDING UNIT THANX ANY AND ALL SUGGESTIONS WILL BE APRECIATED THANX AGAIN
 
1

1SLO306

My 97 GTP owns you ALL!
Mar 31, 2005
904
1
17
Muhlenberg, ky
Jul 31, 2006
#2
  • Jul 31, 2006
  • #2
these cars read how much gas u have even with the key turned off and out off the ignition
 

monte87

Founding Member
Feb 26, 2001
876
18
49
new york
Jul 31, 2006
#3
  • Jul 31, 2006
  • #3
bad sending unit, no doubt, or the needle is struck in that one position. i would say bad sending unit though. yank that crappy gauge add a autometer and swap the sending unit-and be done with that headache forever, like i did.
Anthony
 

bullitstang1313

Member
Jan 21, 2003
713
0
16
Indianapolis / Columbus, Indiana
Jul 31, 2006
#4
  • Jul 31, 2006
  • #4
The only way to really troubleshoot this problem is to drop the fuel tank. The sending units in these cars go bad quite often or at least mine have. The sending unit is just a variable resistor. The more full the tank the higher resistance, often times the sending unit gets an open in the circuit causing the resistance to be infinity hence a full tank. You can check the gauge by hooking different resistors to the wiring. I can't remember off hand what resistance is full and what is empty, but if you can do a search on here; I've seen this on here before.
 
You must log in or register to reply here.

Similar threads

Electrical Oil Pressure Gauge IN Dash Cluster Unresponsive
  • Nine Finger Wrenching
  • Jan 7, 2025
  • Fox 5.0 Mustang Tech
Replies
17
Views
1K
Fox 5.0 Mustang Tech Jan 8, 2025
85GTStangGuy
7
1970 Mach 1 Fuel Gauge Issues
  • 70 Mach
  • Jun 13, 2024
  • Classic Mustang Specific Tech
Replies
7
Views
2K
Classic Mustang Specific Tech Sep 1, 2024
Mach1 Driver
M
Place to Avoid: Jamison Auto Group in Gulfport, MS
  • D Durden
  • Oct 20, 2025
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • 2 3
Replies
46
Views
3K
1965 - 1973 Classic Mustangs -General/Talk- Jul 16, 2026
Noobz347
K
TKX Transmission Shifting Problem
  • KWC156
  • Jun 23, 2025
  • Other Auto Tech
  • 2
Replies
21
Views
3K
Other Auto Tech Jun 13, 2026
427nostang
4
J
Progress Thread Family member 1989 GT- Backstory and updates
  • JRC99
  • Apr 19, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
15
Views
1K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Oct 26, 2025
JRC99
J
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?