Another Kubota fuel gauge stuck on full

[srs]

After 4 years of ownership and 270 hrs the fuel gauge on my B3030 HSDC is now stuck on full. I removed the dash to check for tightness of all wires, everything appears fine. I removed the sending unit and tested the float in a bucket of diesel fuel and it moves freely up and down. The weird part is when I removed the sending unit from the fuel tank and connected the two wires to it, one a ground and the other power it worked fine. I move the float up and the gauge goes to full, lower it and I can watch the gauge drop. Lower the float all the way the gauge goes to empty. I then reinstalled the sending unit in the fuel tank connecting the same wires in the same order but when I turn the key to on it goes right to full. Turn the key off it goes to empty.

I also removed the battery ground to check for corrosion but it was very clean.

I removed the power wire feeding the sending unit and touched it to the ground of the sending unit, gauge went to full.

I removed the ground wire from the sending unit, then attached a long piece of wire to the ground on the sending unit and then touched a 澱olt on the frame, still reads full.

I removed the sending unit and took the cover off. Everything looks like new, no broken parts.

Others have suggested an ohmmeter but even if I had one I would not know how to use it. I guess if it is imperative I have an ohmmeter to definitely figure out what is wrong I could get a cheap meter from Harbor Freight and learn/try to learn how to use it.

FYI I have approximately 1/2 tank or less of fuel.

Any suggestions? I thank you in advance. Stanley

 

[pmhowe]

典he weird part is when I removed the sending unit from the fuel tank and connected the two wires to it, one a ground and the other power it worked fine. I move the float up and the gauge goes to full, lower it and I can watch the gauge drop. Lower the float all the way the gauge goes to empty.

So, you know that the sending unit is working properly, and the gauge still works properly, and the system works properly when the wires are connected the way you did in the test. That would indicate to me that there is still something wrong in the way you have the wires connected on the tractor. I would re-check that. I知 curious as to what led to the initial problem. Had you made some wiring changes?

Good luck. Let us know how you make out. PMH

 

[srs]

That would indicate to me that there is still something wrong in the way you have the wires connected on the tractor. I would re-check that. I知 curious as to what led to the initial problem. Had you made some wiring changes?

Good luck. Let us know how you make out. PMH

pmhowe, thanks for the reply. I checked and double checked the wiring. There are only two wires going to the sending unit that I had removed, the yellow/blue for power and a black/can't remember the second color. How this whole thing started is I had filled the fuel tank to the top to cut the grass for the last time. I cut the grass as usual and I normally use about 1/2 tankful. All during the cutting I noticed the fuel gauge never moved from the full position. After cutting and putting the tractor away I checked the tank and realized that I did in fact use about a 1/2 tankful but the gauge showed full. That is where I am at now. Again thank you.

 

[k0ua]

Ok. so you are telling us, If I read you correctly, that the sending unit removed from the tank and hooked up to the circuit works perfectly when you manually manipulate the float between the fully "floating" position to the all the way down "EMPTY" position. Correct?
Now think about this, how could this be? The only way I could explain that is that for some reason when you put the float back in the tank it becomes mechanically stuck in the up position and gravity cannot overcome this resistance to let the float drop.. Or did I not understand what you said?

James K0UA

 

[k0ua]

By the way, buying a good VOM (Volt Ohm Meter) and learning how to use it is one of the best investments you will ever make in your life. In fact I like to have both a Digital VOM and an Analog VOM. But if money is tight, get the Digital first. And Analog VOM is better to see dynamic things happeining (put it on a potentiometer for instance and move it thru its range and watch for that "bad spot" in the pot) and a Digital is superior for making measurements of static things (12.6 volts. 153 ohms, 1.25 amps) You need both and an understanding of Ohms law. Good luck.

James K0UA

 

[srs]

Ok. so you are telling us, If I read you correctly, that the sending unit removed from the tank and hooked up to the circuit works perfectly when you manually manipulate the float between the fully "floating" position to the all the way down "EMPTY" position. Correct?
Now think about this, how could this be? The only way I could explain that is that for some reason when you put the float back in the tank it becomes mechanically stuck in the up position and gravity cannot overcome this resistance to let the float drop.. Or did I not understand what you said?

James K0UA

kOua, You bring up a good point about the float sticking in the up position. I never really thought about it but maybe this could be the problem, but when I replaced the sending unit back in the fuel tank I was real careful about not bending or disturbing the float or wire holding the float. I need to recheck this. And you too are correct about the volt ohm meter. Thank you.

 

[k0ua]

Ok. something else. I looked in the workshop manual of my own tractor, and it is more complicated as there is a computer module involved in the source voltage not just a simple pot to drive the meter. Now your tractor may or may not have this. and another possibility is when you re-install the sender back in the tank, perhaps there is a connection on the sender (circuit board?) that may be loose or not making good connection when you re install it, but might work perfectly when you have it out in the air. Can you slide the sending unit down in the tank and hold it gently by hand and see if the 1/2 tank of fuel will register on the gauge without tightening the mounting bolts.?

James K0UA

 

[srs]

James, no computer module or circuit board. The sending unit is a simple rod with a slide type mechanism that is wrapped in thin wire which I'm guessing sends the signal to the gauge. I got to thinking too that next time I take the sending unit out of the fuel tank I will tie band the sending unit arm to the empty position, reinsert it into the tank and see what the gauge says. I don't have enough room to hold the sending unit by hand. You have to insert the sending unit, twist it this way and that way to finally get it to go in. I remember the last time I fueled the tractor I topped the tank off by bringing diesel fuel all the way up to the top of the filler neck, which I've done numerous times in the past with no issues. Again I appreciate your efforts!

 

[k0ua]

James, no computer module or circuit board. The sending unit is a simple rod with a slide type mechanism that is wrapped in thin wire which I'm guessing sends the signal to the gauge. I got to thinking too that next time I take the sending unit out of the fuel tank I will tie band the sending unit arm to the empty position, reinsert it into the tank and see what the gauge says. I don't have enough room to hold the sending unit by hand. You have to insert the sending unit, twist it this way and that way to finally get it to go in. I remember the last time I fueled the tractor I topped the tank off by bringing diesel fuel all the way up to the top of the filler neck, which I've done numerous times in the past with no issues. Again I appreciate your efforts!

Sounds like a plan. keep working at it and investigating. I assume the tank is plastic isn't it?

James K0UA

 

[srs]

I assume the tank is plastic isn't it?

James K0UA

Yes sir!