B7800 shutdown

[iamhistory]

Just an update on this situation:

I've been running my tractor since my last post by jumping the starter. The key will click when turned on but will not turn the tractor over. I turn the key on and use a wire to jump the starter. I use the tractor and it works like normal until I turn it off. Then I have to do the same things over again to start and run it next time.

I did track the problem down to the fuse box area where the wires comes out of the firewall near the fuse box. When the tractor is running and these wires are moved around, the tractor stalls. So when I would jump the starter and run the tractor, hitting bumps or something would stall the engine.

Once I tracked it down to those wires in that area I simply positioned and zipped tied the group of wires so they would not bounce around and now it has only stalled twice in 4 months while running.

I hate the fact that I can't figure out what's going on and I really want to get this fixed. The dealer though wants hundreds of dollars to bring it in and look it over and I hesitate at doing that. It's gotta be a bad switch or fuse somewhere and possibly a short. I just can't track it down completely. No fuses are blown and all safety switches have been tested, sprayed, toyed with, rocked back and forth, etc. etc. and still nothing. Besides replacing every switch, I have checked everything suggested and thought of.

I've narrowed it down but haven't nailed it yet. Good enough for now but it really bugs me.

 

[BeezFun]

Once I tracked it down to those wires in that area I simply positioned and zipped tied the group of wires so they would not bounce around and now it has only stalled twice in 4 months while running.

Wow man, I feel your pain. Thanks for posting an update on what's going on. Sounds like you've diagnosed problem to intermittent connection in loom near fusebox/firewall. Could a mouse have chewed through wiring and you can't see it? Or since it's coming through the firewall, maybe the insulation got rubbed off the wires? I think I'd loosen that loom, separate the wires and inspect each one, and start wiggling them one by one right up to the fuse box to figure out which one is bad. I would guess it's possible the starter solenoid is also getting intermittent connection from this fusebox area, which might be why you can jump start it with a wire but it won't crank with the key. If you find the area where there's a problem, I'm guessing you'll solve both your problems.

 

[crazyal]

I think what you'll need to do (or your dealer could do it) is pull the wire harness and inspect it. I'm sure your dealer would just replace it with a new one but if it was me I would just find the problem and fix it myself. I'm guessing that you may have a broken wire, maybe from a mouse, a stick or something, or chafing. Another option could be that the insulation got damaged on one of the wires from rubbing on something and when it moves it shorts to ground or to another wire. There's also the chance that a connector that's crimped onto the end of a wire is loose or poorly crimped. Either way I think you're going to have to take it apart to find the root cause of the problem.

 

[gengine]

Sounds like your not getting power from the key to the switch terminal on the starter. If you are jumping from the bat. Terminal to the switch terminal, then your starter solenoid is fine. If your jumping the two large terminals, then you haven't ruled out the solenoid. If you find it's not the solenoid, the wiring behind the fuse box is your big clue. Wether it's the solenoid or not, the intermittent short still needs fixed. That in itself may be keeping it from starting with the key.

 

[gengine]

I just read another post of an in-line fuse on the key switch of another kubota. Maybe something to investigate...

 

[wcampbell47]

Had a similar problem with my B7510 bought in 2007. Run a jumper wire from the hot side of the battery to the wire on the fuel solenoid. When you connect you will hear a click. With the jumper wire in place my tractor ran until I removed the jumper wire. Dealer ordered the "computer" that is under the dash. Came from Japan. Issue solved.

In your case look for a broken wire. When the unit is cold the insulation contracts enough for the wire to make contact. The unit heats up from running, the insulation expands and the wire loses contact. Many years a go an old Massey Harris had a broken spark plug wire that we finally found.

Just saying .....