• 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
fuel guage/sending unit
#1
ok , another electronics mental midget here... how can I test the fuel sending unit in the tank? can I jump it out? if there's one wire going to the gauge and the other is ground how does it get its power? is it governed by ground resistance? It's on a 72 mach 1...….
  Reply
#2
Disconnect it from the wiring harness and using a meter it should read 73 ohms empty 10 ohms full. You cannot measure the ohms with it connected to the wiring. There is a specific setting on the meter to measure ohms. If you don't know how check the instructions or Youtube.

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
  Reply
#3
The positive side of the gauge connects to the instrument voltage regulator and the negative side connects to the sending unit and provides the variable ground reference at the resistance values Jeff mentioned.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
  Reply
#4
thanks guys!!
  Reply
#5
(08-28-2019, 08:20 AM)don blanchard Wrote: thanks guys!!
so I checked the resistance and all's good there, checking the constant voltage reg. the pos side was flashing???? is this normal? also looking at pictures of them on e=bay it looks like the one I have is for a 74-86..are they interchangeable? I also have a tack
  Reply
#6
I believe they are interchangeable. Yes,they pulse. That is how they reduce the average voltage. There are solid state electronic ones available that provide a constant output. If you get one make sure it's adjustable.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
  Reply
#7
(08-28-2019, 10:55 AM)Don C Wrote: I believe they are interchangeable. Yes,they pulse. That is how they reduce the average voltage. There are solid state electronic ones available that provide a constant output. If you get one make sure it's adjustable.
so does it have to be adjusted when used? if so how
thanks, don
  Reply
#8
Adjusting the voltage up or down allows you to fine tune the gauges, especially the fuel gauge. The stock ones have what looks like a little metal tab sticking out of the plastic, that can be turned to change the average voltage output, by adjusting the tension on the bi-metal spring in the unit.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
  Reply
#9
Thanks, the one I have does have a little tab/pole...if I get brave I might try it. thanks for all your help!!
  Reply
#10
Fill the tank before adjusting so you can use the full mark as a basis for your adjustment

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
  Reply
Share Thread:  


Possibly Related Threads…
Thread Author Replies Views Last Post
  Do fuel gauges fail in this manner? Flatback72 8 1,315 01-14-2018, 11:18 PM
Last Post: Flatback72
  Fuel level sending unit CoolCat33 2 553 10-29-2017, 02:26 PM
Last Post: CoolCat33
  Electric Fuel Gauge AOCUSNRET 4 722 10-03-2017, 04:42 AM
Last Post: AOCUSNRET
  Fuel gauge wiring to tank sending unit routing? 72 H-code 0 711 05-16-2017, 03:03 PM
Last Post: 72 H-code
  fuel gauge Fraz2112 1 589 03-08-2017, 10:03 PM
Last Post: midlife
  Factory Guage Test cheezsnake 10 1,510 07-24-2016, 06:45 PM
Last Post: will e
  routing for fuel gauge wire fonzogt25 2 669 07-17-2016, 09:44 AM
Last Post: fonzogt25
  Fuel Guage and horns BDK 2 688 06-01-2016, 09:12 PM
Last Post: BDK



Users browsing this thread: 1 Guest(s)