B7800 shutdown

[iamhistory]

So my 7800 just shut off the other day and I haven't been able to start it since. It shut off abou 15 minutes before that and started up with no problem. Once it shut off this time, that was it.

My son was sitting on the seat and I was putting some wood in the bucket and it simply turned off. I was sure that it was just a safety switch somewhere but I am now stumped after a week of not being able to figure out the problem.

I've read every thread I could find on what the problem could be and what other guys have experienced and I've tried everything they did: seat switches, jumping the terminals, checked fuses, checked pedals, checked gear levers, charged the battery, etc.

I can't figure it out. I have lights but no turnover when I hit the key. It has 346 hours on it, has had no problems and it is well maintained. It was running like a champ for an hour or so before the shut off and now it's sitting there.

Can anyone help me out with some ideas? It's probably something simple but I'm stumped.

Thanks guys.

 

[RoyJackson]

Have you tried jump starting from a known good battery (that may have been what you meant by "jumping the terminals")?
Old batteries can take a charge, but they may not hold a charge (as soon as you start cranking, the battery is drawn down). A bad battery is what it sounds like since you have lights, but no cranking.
Another thing to consider is a bad ground at the battery or the starter. Definitely check where the grounds connect to the tractor's frame.
Good luck!

 

[BlacknTan]

There was a thread about this recently, and I can't find it, but there is another switch with a plunger down near where the hydraulics return to the tank. The plunger seems to get sticky and cause this problem

I'll keep looking for the thread..

 

[BlacknTan]

Here's the thread..

Herringchoker figured it out..

Hope it helps.

http://www.tractorbynet.com/forums/kubota-owning-operating/153385-kubota-7800-wont-start.html

 

[grsthegreat]

I'm not sure about the Kubota series, but most other tractors have a MAIN fuse located near the starter....a 50-60 amp fuse. have you checked this fuse also???

Also, have you determined that its getting fuel past the fuel pump before the injector pump. There is also a stop solenoid that may be stuck.

 

[BeezFun]

Since you have lights but no crank, I'd pull the battery and take it to battery place, they'll test it for free with a load on it. If it passes the test, bring it home and jumper it right to the starter to see if it turns over. If it does, you've got a bad cable, connection, ignition switch problem, etc. If battery doesn't pass load test, get a new one and that should fix it.

 

[iamhistory]

Ok, so here we are two weeks later and my tractor is still sitting. I have made some progress with it and got it started but it will not stay running.

It was not the fuses. It was not the battery. The safety switches and seat switches are showing they are working properly. The fuel solenoid was shut off and jumping the starter would not start the tractor b/c of not having fuel. The relay in the dash was taken out and tested to find that it was fine. We also tested it overnight under a load and it was still fine. Called the dealer and he told me it was the voltage regulator (without looking at the tractor). And we were getting pretty well stumped.

I started playing with the switches and wires this weekend and heard an audible "click" when I turned the key on and off. That "click" was no previously heard. It turned out to be the fuel solenoid (I think) and when I heard the click and jumped the starter, the tractor fired right up. It would run but if I got off the seat even in neutral the tractor would shut off. I bypassed the seat switch and put a jumper wire on so I could get off the seat and the tractor would still run. I actually was able to mow my grass this way for about an hour.

Suddenly, the tractor shut off again and would not start back up. I had no fuel. I went out the next morning, the ignition "clicked" again, I jumped the starter and fired her up. Had fuel and even hauled some wood around. Suddenly again, she shut down and has been that way for two days.

I can't figure it out. It seems like one of the switches is telling us that the mower deck is engaged but we have tested them, checked the plungers, checked their contact, etc. and really can't find anything wrong. But something is shutting my fuel off and it has to be a safety switch somewhere.

Any ideas from my update? This is driving me nuts, not to mention, I need the tractor to run dependably because chores are piling up.

 

[iamhistory]

I should also mention that I cannot start the tractor with the key. We tested the ignition switch and it is working properly. The key turns and shows all lights, accessories and glow plug are good to go but it just won't start the tractor. Nothing happens........no turnover attempt, or anything.

I have to jump the starter to start the tractor. As mentioned, it doesn't stay running. We checked the ground and all wires for being loosed, broken, etc. We didn't find anything suspect and I'm running out of ideas of things to check.

What the heck could this be? I'm guessing it is something right under my nose and relatively easy to handle.

 

[grsthegreat]

well the fact that the key wont start it i think it HAS to be a safety switch somewheres. They have them on the PTO, the seat, the clutch and sometimes on the gear shift/HST levers.

If the key switch checks out OK, the signal is being cut between the key and the starter. Jumping it is bypassing that. Now that it isn't starting does the stop solenoid still click when the key is turned?

I had to just recently replace my stop solenoid for this same reason...no click when key is turned, and no fuel to tractor.

 

[Motractr]

I should also mention that I cannot start the tractor with the key. We tested the ignition switch and it is working properly. The key turns and shows all lights, accessories and glow plug are good to go but it just won't start the tractor. Nothing happens........no turnover attempt, or anything.

I have to jump the starter to start the tractor. As mentioned, it doesn't stay running. We checked the ground and all wires for being loosed, broken, etc. We didn't find anything suspect and I'm running out of ideas of things to check.

What the heck could this be? I'm guessing it is something right under my nose and relatively easy to handle.

There is a safety switch on the forward/ reverse pedal below the floor board. To check, put the trans in neutral and rock the pedal back and forth while turning the key with the clutch depressed. Also, the seat switch always gives me problems. The pedal switch is kind of hard to see. Also, check the 5 amp keystart fuse. I keep extras on hand because they blow every once in a while.