Go BottomKubota B7100HST 1994 could not start the engine
 | Terry720
Join Date: Feb 2007 Posts: 2 Virginia 
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2007-02-20 139917
Dear All,
I bought a used a kubota b7100HST, 1994 with about 600hrs on the dial, used it for about 15 hours last summer. I used it mainly for the mowing and I could not start it any more at the end of last summer. It does smoke white while starting and clear up usually, if the grass is too thick it does black smoke but will clear up after I slow down the speed. Please let know where should I start checking to get it started. I had tried starting fluid and it started for one time. I do not use the tractor quite often, probably once every two to three week for about an hour of mowing. I donot have experience on diesel engine and every single help is very much needed.
Thanks in advance. Terry
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 | earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan 
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2007-02-20 139920
Have you changed the fuel filter? ....
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| Terry720
Join Date: Feb 2007 Posts: 2 Virginia
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2007-02-21 139936
Hi Earthwrks,
Thanks for the reply, I have not change the fuel filter, but I have taken it out of the bowl and checked it. It seems to be clean without any dirts or blockage. I had blew it with air inside out and seems to be OK, as it bubbles on the whole surface consistantly. If I should change the fuel filter I will do so over the weekend. I had crank the engine for couples of turns may be more than ten seconds but it did not start except white smokes. It usually start on the right up. I do not want to take it to the dealer, as I live on a very limited budget and they charge hands and legs. Hope you all can understand my situation.
Thanks,
Terry ....
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| earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2007-02-21 139937
White smoke is a good sign it's getting fuel.
(From my experience before I found my glow plug relay was bad, I would crank it with with a squirt of starting fluid.)
Sounds to me it has glow plugs not working. I'm no expert on 'botas, but there might be a procedure to start it like holding the switch for a time, or waiting to start until the indicator light goes out. Might be a bad relay, loose wire, etc.
Have you tried starting fluid? It should start right up with that. DON'T use starting fluid if you think the glow plugs are working--could start a fire... or worse. ....
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Add PhotoKubota B7100HST 1994 could not start the engine
 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2007-02-22 139948
Terry, other than EW good ideas, I would suggest you try an experiment, especially considering how infrequently you use the tractor.
Park a vehicle with a big battery (diesel pickup?) close by to the tractor and hook up booster cables to it, let the other vehicle idle for 10 minutes or so, preferably on a slightly (but not much) higher than nomal RPM, and then try starting the tractor.
If the battery is getting weak, and you don't use the tractor often, you might not realize the engine is cranking much slower than it should be, caused by an older weak battery.
Of course with 600 hours on it, it could be that one or more injectors are leaking down, that is to say, when you park the tractor, the fuel between the injection pump and the injector is dripping down into the cylinder, this will leave an air bubble in the system when you go to restart it. Until this bubble is bled out, by running the engine, the tractor will make white smoke, because the air to fuel ratio is off to the lean side. This will also make for a hard start because there is insufficient fuel to allow it to start properly.
Once you have started it, let it get warm, and go back and see how it starts an hour or so later, if it starts absolutely normally, look at the battery, if it starts well but makes much either black or white smoke, it's one or more injectors. Pull them and get them overhauled or replace them.
The glow plugs and relay can be tested with nothing more than a multi-meter. If you don't know how, just ask. :)
Best of luck. ....
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| earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2007-02-22 139964
Murf: My "ideas", you no like?
I'm all ears if I'm on the wrong track. Like I said I'm not a mechanic but play one on the Web. :)
BTW, I do see merit in the good battery theory. (You didn't mention it could be a bad connection too which I have a problem with on my blue even though it has a gell cell.) ....
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Add PhotoKubota B7100HST 1994 could not start the engine
 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2007-02-24 139990
The biggest problem of electrical operational problems, strating and lights is most often the grounds or wiring on a five plus year old machine with any make that we sell.
Good call again Murf! ....
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| takone
Join Date: Feb 2007 Posts: 5 tennessee
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2007-02-26 140018
I had the same starting problem on my B7200 It would turn over but not start. When I boosted it with my pickup it started right up. It turned out to be battery cable clamp wasn,t making real good cantact with the clamp even tho it appeared to be ok. Put a heavy duty clamp on and it solved the problem. You can check the glow plugs by removing them and connecting positive wire to the terminal and grounding the side of the plug it will get red hot quickly if working. Bill ....
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Add PhotoKubota B7100HST 1994 could not start the engine
| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2007-02-26 140025
Jeff, no it's not that I 'didn't like' your ideas.
You were absolutely going down the right road, but for a shade-tree mechanic with some experience, diagnosis is easy. FOr a pretty rank amateur with little mechanical experience, and even less tractor experience, the simplest test is the best one.
Bear in mind, an engine rolling over on a starter is turning just fast enough to catch at the best of times, add any one, or several, complicating factors and you're lucky if it starts. In this case, a poor connection somewhere, glow plug problems, and or a weak battery would all be overcome by simply making it spin, but good!!!
I don't like to advise anyone with out a good bit of experience to use ether (quick start) on a diesel, too much chance for an ooopsey! I like to tell people to use WD-40 or something like that instead. Besides, the white smoke was a giveaway that it was already getting some fuel, the problem was more likely lack of ignition, a faster spin helps that, both because of the speed, but also because it makes more heat at a faster spin to light up without the glow plugs.
Thanks Art.
Best of luck. ....
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