Kubota B-7800 dies suddenly while under load, Help

[Bawb]

Greetings, I just found this board and am new here. I could very much use some of the wisdom here. Here's my problem.
I own a B-7800, about 2 years old. I am having a intermittent problem that is driving me crazy, any help or advice would be appreaciated more then I can tell you. The symptoms are not always exactly the same, and it's driving me crazy trying to figure it out.

1) Battery is good, about two months old.
2)I've checked the safety switches and they all seem to be operating properly.
3) Sporadically, while running under load, the tractor will just die. Definately feels like an electrical problem to me. It's like someone turned a switch.
4) There is still power, all lights and gauges work.
5) Sometimes the engine will crank, but you cannot hear the fuel shut off solenoid click when you turn the key, and it will not start in this state.
6) If you wait long enough (between a few minutes and overnight!) the fuel shut off solenoid will eventually click, and the engine will start immediately.
7) Sometines, after it dies, it will not crank at all. Again, if you leave it sit long enough, it will eventually come back to life.
8) Sometimes wile driving it, you can feel it die for a second, and then come "back to life" immediately.

This is driving me crazy, especially because of the sporadic, and inconsistant nature of the problem. I can't "take it in", cause of course when it's working there is nothing they can do to troubleshoot it.

ANY advice, suggestions, theories are welcome. Thank you in advance for reading my post, and trying to help.

Bob Alabaster

 

[j48j48]

Try the safety switch under the seat, I think that may be the problem. KDJ

 

[fishdoc]

I feel you pain.

I had a similar problem with my 7610. While you are waiting for more replies specific to your problem you might want to read through this thread and see if there is any useful info. I do not think it is your seat switch btw..... but that is so easily tested by disconnecting it and taping the ends together for a check.

Richard

http://www.tractorbynet.com/forums/showflat.php/Cat/0/Board/owning/Number/716497/page/0/view//sb/5/o/all/fpart/1/vc/1

 

[Bawb]

Hi Fishdoc,
Yeah, I already found your thread and read through it. It sounds like our problems are very similar. Unfortunately, it does not seem like you ever found out for sure what the problem was. I'm still stumped. There is nothing worse then an intermittent problem. At least if the darn thing just broke, I could figure out what was wrong with it and just fix it. So far people have suggested ...
a) fuel starvation. Maybe, but I don't think so. If it was fuel starvation, why would the fuel shut off solenoid not engage? Plus, when it happens it's instant. No sputtering, coughing or whatever, it just dies immediately. I could be wrong, but my gut feeling is that it's electrical, not fuel.
b) Seat switch. No, easy enough to check with a voltmeter, which I did, and they are working fine.
c) Bad ignition switch. Could be. Next time it happens I'm going to check to see if the fuel shut off solenoid is getting voltage, as suggested.

So, so far I'm still at a loss. :::::sigh::::::

 

[Bawb]

Being new to this forum, I accidentilly posted this thread twice. So as not to be annoying, I'm going to copy the other replies here, and then delete the duplicate thread....

CP1969 said...
Immediately after it dies and won't start, use a voltmeter to see if power is getting to the fuel shut-off solenoid. If not, you probably have a bad ignition switch.

Bear in mind I am not familiar with your tractor or its wiring, but that is what I would check. If you don't have a voltmeter, you could run a wire from the batter to the valve and see if it then starts up.

N4807G said...
More than likely fuel starvation. What about your dealer? What did they say?

 

[cp1969]

heh, heh....I meant 'battery', not batter. Maybe I had the baseball playoffs on my mind.

It is a fuel starvation problem, of that there is little or no doubt. Unless the injection pump has lost its mind, my guess is that it is caused by power to the fuel solenoid being interrupted.

 

[fishdoc]

Hey Bawb.....

I never positively ID'd the problem but it seems to be gone and I now have about another 15 hours behind me.......

If it were an airplane or a boat I would be worried.....

The symptom you describe " sometimes it doesn't even crank "...... I can't help but think that you need to find the "key stop" fuse and check the connection..... replace that fuse even if it doesn't look bad.

Good luck!

 

[nharrold]

Had a somewhat similar problem once with my 7800. Turned out to be dirty fuel.

 

[Henro]

Just before it was time to change my fuel filter on my B2910 (380 hours on the tractor), I had problems somewhat similar to yours. The tractor would almost die out, and then shortly afterwards work hard without problem, and then start to die and hardly idle unloaded for a bit, and then again work normal, and so on.

Turned out to be a clogged fuel filter. I had arranged to have my dealer come and get the tractor, as the warranty was about up, but on a whim decided to change the fuel filter.

New fuel filter, no problems afterwards. Two hundred plus hours later still no problems.

Change the fuel filter and see what happens. Very simple and inexpensive to do.

I could not believe it could be the reason for intermittant problems but it was in my case.

 

[nharrold]

Had a similar problem with my B7800, turned out to be a whole lot of water in the fuel.