Fuel gauge acting weird

[Welder Dave]

Wondering if anyone has had the fuel gauge on their skid steer stick on full and/or stay on full when the key is turned off? At half a tank the gauge goes to empty with key off. Used to always go to empty. Gauge also seems to read higher than actual fuel level too. Not sure if I have gauge issue or maybe a sending unit issue. It's a Faria fuel gauge in a Thomas skid steer. It's acting weird after new glow plugs, glow indicator and key switch. Machine has about 4500 hours.

 

[56wrench]

If is easy to get at, i would pull the sender and check the tiny rheostat windings where the contact actually changes the ground resistance. They can wear through over time. If they are under a small cover, you can connect an ohmmeter to the terminal and the mount plate and cycle the sender manually and check for smooth and even variable resistance through the full range

 

[Welder Dave]

I was reading Faria gauges can stick but you can free them up with a magnet. Works on other gauges too, even on vehicles. I would have taken the sender out if it was easy. The problem is that it's right underneath where the lift cylinder is pinned. I could barely get my fingers in to to put the nut back on the sender wire stud. I can take the pin out easily enough but I'm not sure if I'd have to take any hoses off to be able to move the cylinder enough out of the way. Certainly don't need an oil mess. If a magnet doesn't work I'll just have to run the machine and see if the gauge comes down. I'd have to get down to about 1/4 tank before I could take the sender out if it's required.

 

[Welder Dave]

Wanted to update this thread. I tried a magnet on the gauge and it didn't do anything, it stayed on full with key off. I had to move the machine out of the way and a couple hours later I tapped on the gauge a couple times and it went to empty. Great I thought. Machine off and I turned the key on and off and the gauge went from full to empty. Started machine to park it and noticed when running and I shut the key off the gauge only went down to a little over half. Shut the machine off and turned key off and it went to empty. Not sure why it wouldn't go to empty when running but key off? I guess I'll have to wait till it dries up and I can run it for a few hours to see what it does. Does this sound like a sending unit issue?

 

[BluewaterLa]

I wonder the same as you though I would run the fuel low and pull the sender to test it and see if it is sticking. Normally from my experience its the sending unit crapping out. Only gauge I've ever had to change out was one that was broken from the front by some ''unknown'' event.

 

[Welder Dave]

I would check the sending unit but I'm not sure if I can move the lift cylinder out of the way enough without taking any hoses off it.

 

[HarleyHappy]

You can move the cylinder enough to get the sender out.
Best way to address this is to take the sending wire off the sending unit, that’s hard enough in its location.
Anyways, with the wire off, hook up a meter and measure the OHMS and take cap off of gas tank and using coat hanger, manipulate the float and you should be able to see the meter changing OHMS as you move the float.
I actually have to replace my sender but have almost a full tank and have to get it below a third of a tank before I can get it out.
I already have the pin moving for the cylinder base, that was a pain in the ass.

 

[Welder Dave]

I wanted to try and move the float but couldn't see it when the tank was low using a flashlight. The gauge did go down after running the machine so I'm hoping it was just stuck. I'll have to run the tank down again and see what the gauge does. The gauge was moving around when I made jerky movements with about half a tank. That's why I filled it up again to see what it does.