• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

Testing gas gauge

  • Thread starter Thread starter madbrad
  • Start date Start date Sep 1, 2005
M

madbrad

Member
Mar 6, 2003
72
0
6
Albuquerque NM
Sep 1, 2005
#1
  • Sep 1, 2005
  • #1
I just put in my new auto meter gas gauge and when i turn the ignition on it barley moves. I put 10 gallons of gas so it should move more than that. Im thinking it might be the sender ans i bought a digital voltmeter to read the omh's but not sure how to do it, or what it sould read. Any other ideas on things to check? I dont know if the gauge work before i install the new gauges since the car was just a rolling chassie when i got it.
Thanks
 

Bullitt

Packin' Heat
Founding Member
Jan 13, 2000
2,743
0
47
Houston, TX
Sep 1, 2005
#2
  • Sep 1, 2005
  • #2
summit lists the resistance reading for the various autometer gauges. you have a "ford" style, so just look up your gauge in summit.

as far as measuring resistance. put your voltmeter on 0-200 ohms and bridge between the sending unit and a spot on the frame. that should give you the gauge reading (if i remember correctly). it's either that or you disconnect the sending gauge wire and run the voltmeter in series...

been a long time since i did it so i can't remember.
 
F

ForceFed70

That's why they call it "dope"
Founding Member
Dec 6, 1999
4,818
1
69
BC Canada
Sep 2, 2005
#3
  • Sep 2, 2005
  • #3
A quick test to do would be to disconnect the wire from the sender. The guage should stay on empty.

Then take the wire and ground it to the frame. The guage should read full.

Won't tell you if it's the right guage for that sender, but it will tell you if the wiring is good.
 
S

steel1212

Active Member
Jun 24, 2004
1,180
0
36
Frankfort, Ky
Sep 3, 2005
#4
  • Sep 3, 2005
  • #4
Also, I think they suggest that you ground it to the tank. Mine will read full for a little while but as I use up fuel it quickly goes to 1/4 tank. I'm going to run a wire back to the tank and see if that helps any.
 

stangman16

Active Member
Nov 16, 2004
640
4
29
San Antonio, TX
Sep 3, 2005
#5
  • Sep 3, 2005
  • #5
steel1212 said:
Also, I think they suggest that you ground it to the tank. Mine will read full for a little while but as I use up fuel it quickly goes to 1/4 tank. I'm going to run a wire back to the tank and see if that helps any.
Click to expand...

Wow, that can explain why mine has a 'mind of it's own'... lemme know if that solves it for you. very interesting.
 

pabear89

Active Member
Apr 15, 2003
2,126
0
46
High in the Hills of So Ca with the Voices in My H
Sep 4, 2005
#6
  • Sep 4, 2005
  • #6
steel1212 said:
Also, I think they suggest that you ground it to the tank. Mine will read full for a little while but as I use up fuel it quickly goes to 1/4 tank. I'm going to run a wire back to the tank and see if that helps any.
Click to expand...

Replace the sending unit.
the windings are failing on it.

Same as if it only goes partually up, when the guage reads half and your tank is full.


PB
 
S

steel1212

Active Member
Jun 24, 2004
1,180
0
36
Frankfort, Ky
Sep 4, 2005
#7
  • Sep 4, 2005
  • #7
Mine is a brand new sending unit, doesn't mean its not bad though. I grounded my gauge to the top of the tank today...still same thing just goes to 1/4 tank. I may have to invest in a new sender. I'm probably going to check the ohms tomorrow just to make sure.
 

Capt Dan

New Member
Mar 31, 2005
237
0
0
College Station, Texas
Sep 5, 2005
#8
  • Sep 5, 2005
  • #8
steel1212 said:
Mine is a brand new sending unit, doesn't mean its not bad though. I grounded my gauge to the top of the tank today...still same thing just goes to 1/4 tank. I may have to invest in a new sender. I'm probably going to check the ohms tomorrow just to make sure.
Click to expand...

Grounding it should make it go to full. I think that rules out the sender. Must be the guage or the wire. Try grounding it to the frame. Maybe you have a bad ground between the tank and the frame.
 
S

steel1212

Active Member
Jun 24, 2004
1,180
0
36
Frankfort, Ky
Sep 5, 2005
#9
  • Sep 5, 2005
  • #9
It was grounded to the frame before I moved it. The gauge will go to full when the tank is full but quickly goes to 1/4 tank as the fuel is used.
 
You must log in or register to reply here.

Similar threads

F
Difference between 83-86 EFI and 87-97 gas tanks?
  • ForeverDrivin
  • Mar 30, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
5
Views
158
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Mar 30, 2026
ForeverDrivin
F
K
Electrical 2000 GT Intermittent Engine Shutdown In Motion - DTC U1262
  • kenster1092
  • Apr 13, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
128
SN95 4.6L Mustang Tech Apr 24, 2026
squeak93
C
4375 auto meter air/fuel gauge
  • Canadianfox
  • Jul 27, 2025
  • Digital Self-tuning Forum
Replies
0
Views
93
Digital Self-tuning Forum Jul 27, 2025
Canadianfox
C
H
Fuel starvation issues, 91 EFI to carb swap. Car dying after 1-3 gallons used. EFI tank, electric fuel pump, bypass regulator. Dual fed carb
  • hassler
  • Oct 11, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
8
Views
665
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Oct 12, 2025
nickyb
P
Weird Voltage & Oil Pressure Gauges
  • PNN
  • May 22, 2026
  • SN95 V6 Mustang Tech
Replies
0
Views
29
SN95 V6 Mustang Tech May 22, 2026
PNN
P
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang 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?