Kubota B2910 Fuel Gauge Not Working

[hthomure]

The title of the tread says it all. My fuel gauge always says "full." I'm assuming there's a float in there that's stuck, but don't really know much about it, so I don't know where to begin troubleshooting. Any suggestions?

The sypmtoms are: The fuel gauge always says "full," except when the key is off, then it does move to "empty." So I guess at least I know it's not the needle itself.

Thanks.

 

[aggiehortguy91]

The sending units in both tractors and boats are notorious for going bad. I have never figured out why manufacturers don't use a better sender for these. My BX always reads about 3/8 of a tank, but the process to remove and replace the sending unit is far more difficult in my case that it is worth so I just keep a mental track of fuel use and top off the tank when in doubt.

 

[David-Davies]

If you'r fuel gage allways reads full, I would suspect that you have a bad ground. Unless it's wired differntly than a car. If you can get at the sending unit, dis conect the wire, test for power, if power, then scratch a good ground, see if the neadle goes down.

 

[number two]

Sounds more like the power wire is broken/bad connection,etc.My years with trucks,that was always the problem.Good Luck!Post back.

 

[hthomure]

Thanks folks. I tore into it and pulled the sending unit and cleaned everything up, making sure all the contacts were good, and when I put it back together, it seemed to be working fine. Didn't have to replace anything, fortunately.

Now I have to figure out why the cruise control quit working.

 

[hthomure]

Ok, scratch that. I fixed the cruise control, but halfway back to my farm, the fuel gauge quit working again. It had been working great, then all of a sudden, it just jumped back up to "full."

Ground problem, I'm guessing. But all the contacts were clean when I put it back together. God, I hope it isn't at the other end of the wire. I'll never find it.

 

[hthomure]

I've been thinking about it, and what I might do is just make a new ground. I'll fasten a new wire to the body of the tractor and call it the ground and see if that works. That's a lot easier than trying to track down a loose wire.

 

[David-Davies]

Do you have power at the sending unit when it reads full? If yes, it's a bad ground or it's the sending unit. Do you have power on the ground side of the sending unit? If yes it's a bad ground, if no, it's your sending unit.

 

[hthomure]

That makes sense. I'll approach my next check of it with that in mind. I only know two things right now: One, when the ignition is off, the needle reads "empty." When I turn it on, it goes to "full." That tells me it's at least getting power. Two, when I took it apart and cleaned the contacts and put it back together, it worked until I got a couple of miles down the road with it, then it just quit working and the needle shot back up to "full."

The unit had a little rust on it when I checked it, but the arm moved freely, and it worked for a while. I would think the sending unit would either work or not, not work some of the time and not work at other times.

 

[QueBota]

Here is a quick blurb from a jeep site that briefly describes the fuel sender/fuel gauge system. I belive the tractor should be set up similarly.

Dave

This link is pretty straightforward.

http://www.aa1car.com/library/fuel_gauge_diagnosis.htm

Here is the text from the jeep site

The fuel sending unit wires are located on top of the gas tank
where they are hard to get to without dropping the tank. The fuel sending unit should have a pink wire with voltage on the isolated center post. The other black wire on the sending unit with a tab style connector is a ground to the frame. Make sure it has good contact.

To be sure the problem is not the gauge, you can momentarily short the pink wire on the output of the sender to ground, and this should show up as FULL on your gauge. DO NOT hold it for very long in this position, just touch and release the wire. If the gauge does not move from EMPTY either the wiring has an open circuit (no voltage, or no connection to ground) or he gauge is bad. If it does move, the sending unit is bad.

The sending unit can be checked with an ohmmeter to measure the resistance between the round sender post (pink wire) and ground. It should be:

Resistance Reading
73 ohms Empty
23 ohms 1/2 tank
10 ohms Full

If the resistance falls in this ballpark (depending on how much gas you have in the tank), then the sending unit is fine. If it shows infinitely HIGH resistance, then the sending unit could be bad OR the wire from the tank to the gauge could be open.

The gauge can be tested with the resistance listed above. Run an appropriate resistor to the S terminal of the fuel gauge and to ground and check the readings.