Non working gas gagues

Must be having a rash of this problem.

My Farmall, 706 D, the gauge "works" but just bounces all over the place.

My ole IH Grain truck, 1600, I get nothing on it. I checked to see if there was a fuse for the gauge, there isn't.

Anybody an expert at these things? I am looking for the first place to start in my quest for the problems.

Thanks, Gene

Most use a reostate type system so if you lose ground to the tank you lose the gauge working. I have found one can try grounding the wire going to the gauge and the gauge should move. If it does not move the gauge it self is bad. If it moves then good chance the tank has lost if ground or the sensor it self has gone bad

Good timing, I am trouble shooting the gauge on my 64 F-100. At almost full,of gas, the ohms reading was about 6 ohms across the float , wires removed. I drove about 25 miles and reading was in the 20 ohm reading, put another 25 or so miles on the truck and reading went up again, ( do not remember the reading). So on my truck it looks like the float works ok. The gauge on the dash is not reading correct, it does kind-a work, full of gas reads a bit over half tank and when the gauge reads under 1/4, you better be looking for a station. I am going to try checking the ground to the tank next. Any suggestions?
The wiring diagram for this truck shows a 12 volt feed to the gauge in the dash, then a wire to the float variable resister then to ground. really simple circuit. wish you luck joe

I always have the sending unit go bad so I start there. An OHM meter will tell you if it works. IF you touch the ground to the hot the gage should read one way or the other usually full and stay until you release the connection.

The resistance range over which the sender and gauge operate varies by manufacturer and era made.

Here's some common automotive info. Wish it included IH trucks. Will have to dig a bit deeper for IH and DEERE, etc. specs..

<img src = "https://i.imgur.com/gYqQFHl.jpg">
Fuel Gauge troubleshooting

Don't let me forget it I will scan it fer'ya... I have it for some other oddball stuff also... I brought a gauge tester form a IH dealer that bit the dust it comes in handy...

i agree with Old.. Ground the tank before you worry with anything else.

Sent it email let me know you got it..

I am also happy this subject is getting explored. My 1967 F-100 Ford gauge stopped working a few months ago, pulled the sender and the middle of the wire winding
was pulled from the backing. Bought a new replacement from Dennis Carpenter, no joy. Ohm meter not cooperating, no reading anywhere. Wire from gauge to sender
fine, no short, ground wire from sender to cab fine, wire from relay on back of instrument panel to gauge fine, also tried jumper wires bypassing each to confirm
condition. I did find the 12 volt signal from relay through gauge to sender is not constant, clicks on and off, no idea why. I have an aftermarket repair manual
and a wiring diagram for the truck but neither gives any insight. Lately the gauge may show 3/4 when full or may show nothing or anywhere in between, I carry a 5
gallon gas can now. The truck only has 49,000 original miles, no rust to speak of and lives in the garage until I go to town for food once a week. I'm loosing
hair fast enough without pulling it out in frustration! ;-)

This should cover your issue..

https://therangerstation.com/tech_library/troubleshooting_and_replacing_your_ford_fuel_gauge.shtml

NOTE " If you hook the gauge directly to 12V power you can let the magic smoke out of it FAST"

If you measure the voltage YES you you see it toggle from 0 to 12V. its spose to "The gauge uses a 5 volt pulse supplied by the instrument cluster's voltage regulator".

Its a switch to get an average of 5V it toggles from 0 to 12V if it were on for a second and off for a second the average would be 5 to 6V that is the 5V supply the gauge uses..

If you want to go deeper start a post on your issue... I hope those that don't understand how a Ford system with a voltage stabilizer works set back and be quite... Its somewhat of a different animal...

Google how does the voltage regulator work on a ford fuel gauge

Yes it took me awhile to get a grip on it I took the cluster out and wired it to a sender on my work table using a voltmeter it threw me a curve ball ... I them hooked a DSO on it and saw the light The DSO scope showed me voltage over time not an average jumping around you will see with a DVOM... IF no DSO use a analog volt/ohm meter then you can see the needle swing back and forth...

If the voltage stabilizer is switching its working one thing to remember the base of the VR MUST BE GROUNDED It may be best to run a dedicated ground to it :wink: :wink:

I call those old ford car/truck dashes Gillette dashes they are all metal and have hidden razor blades you are gonna bleed if you would on them much...