Go BottomKubota B-7800 dies suddenly under load please help
 | Bob Alabaster
Join Date: Posts: 1 
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2005-10-15 117913
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) 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.
3) There is still power, all lights and gauges work.
4) 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.
5) 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.
5) 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.
6) 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
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 | kwschumm
Join Date: Feb 2003 Posts: 5764 NW Oregon 
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2005-10-15 117919
When you say under load do you mean the pto is running? I don't know the 7800 but maybe an operator presence switch is failing. The switch might be under the seat. If there's a switch there try fiddling with it or jumpering across it next time it's in that state. ....
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| Bob Alabaster
Join Date: Posts: 1
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2005-10-15 117924
Sorry for being unclear. No, not the PTO, I mean while towing a harrow. And I have checked the safety shut off switches and they are all operating correctly ....
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 | Chief
Join Date: Jul 2003 Posts: 4297 Southwest MiddleTennessee
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2005-10-15 117933
Check your electrical connections at the injector pump and your fuse box as well as grounds. If you are lucky this may be the cause. Otherwise, it sounds like the fuel shut off solenoid on the injector pump may be bad. ....
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2005-10-15 117939
Bob, I guess the first thing that I'd ask is why the battery needed to be changed within two years? I think that your problem for what it was discribed elimintes many of the pieces of the puzzle and all goes to one potential solution if checked out properly. I'd take a good hard look at the ignition switch which is the single component that has control of all the problems you described. ....
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 | harvey
Join Date: Sep 2000 Posts: 1550 Moravia, NY 
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2005-10-16 117958
Have you tested for power at the selonid and the circuit that feeds it? If it has power and won't pull in then you need a new selonid. If it does not Then back ward trace the wire and look for broken connections or switches.
If this has been going on for 2 years I'd rather think you have a problem with a safety switch some where.
I remember a little skinny guy could not get his tractor to run all the time. Come to figure out needed a fat ass in the seat to fully depress the safety switch.
I would not be afraid to run jumper wires around the safetys 1 at a time to eliminate them from being the problem. ....
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 | Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2005-10-16 117963
Other than the fact you can not hear the solenoid open, the other fault that could cause that problems would be a large diameter contaminate in the fuel tank, like rust flakes. It will plug your pick up screen under heavy load and then drop off over time when stopped. You start the tractor again and run until the you bump the tank with a fast flow through the filter and you sputter and die again. ....
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| Bob Alabaster
Join Date: Posts: 1
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2005-10-16 117965
First off, my sincere thanks to you all for your suggestions. Let me try to respond...
1) I don't think it is the fuels shut off solenoid. When this first started to happen, I thought so and replaced it. I saved the old one and the same thing occurs with either one. Seems to me the chances of two of them being bad are slim. Plus the dealer told me they usually either fail, or not, that it is very unusual for one to work sporadically.
2) I will recheck all electrical connections, as suggested. My gut feeling is that this is a intermittent electrical short somewhere.
3) Battery. I live in Arizona, and the tractor has lived through two HOT Arizona summers. It tends to be worked for many short periods of time during the day. It's not that uncommon for batts to fail here due to the heat stress.
4) Believe it or not, I've also replaced the ignition switch. The old one was sticking in the "start" position. The problem has not changed with the old switch, or the new one, and again, it seems unlikely that two of them would be bad, no?
5) I have not checked for power at the solenoid when it would not engage. I will do so at my next opportunity, as this makes sense to me. Believe me there is plenty of weight in the seat when I'm sitting on it. Plenty. I have tested the safety switches, and they test fine, nonetheless I will try jumping them next time the problem occurs just to be sure.
6) Fuel. I'm willing to consider anything. However, I'm not sure how to check this?
Again, thank you all. I run a horse boarding and training facility, and the tractor is essential for the everyday operation of my business. This is not mearly an annoyance for me, but a major problem. Thank you all for your help. I will keep on pluggin' on this until I figure it out.
Bob Alabaster ....
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| Bob Alabaster
Join Date: Posts: 1
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2005-10-16 117966
P.S. This has not been going on for two years. The first year I owned the tractor id did not happen at all. Over the second year it has slow but surely been happening more and more frequently. ....
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| Gearhead
Join Date: Jul 2005 Posts: 75 SEVEN mILE OH
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2005-10-16 117968
If i remember right thers a controller for the shut down system for the engine that has a timer in it, it could be going bad, almost sounds like it,s going to go out completely or it could be loosing a signal from one of it,s feed wires. ....
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| Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2005-10-16 117974
I am not sure exactly how to check the in tank filter on the Kubota. My filter on the Deere gave me problems at about 250 hrs. I guess the tractor was actually about 4 years old at the time. The tank is plastic. I pulled out the fuel sender unit, cleaned the filter and flushed the tank. ....
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| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2005-10-16 117983
You shouldn't have to be fixing this problem. Your tractor is under warrantee and this shold be covered. It does sound like an electrical problem. ....
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| Bob Alabaster
Join Date: Posts: 1
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2005-10-23 118313
Update.....I got it fixed!!!!
After much aggrevation, and unnecessarily replacing several good parts, I got it figured out. It was a faulty neutral start switch on the HST pedal. Since you can't start it in gear without the clutch pedal depressed anyway, it seemed somewhat redundant to me, so I just bypassed it, and now all is well. Thank you all for your help and suggestions, I sincerely appreciate it.
Bob ....
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