Kubota F3680 Engine Stops After Random Intervals

North Idaho Wolfman

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
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Sandpoint, ID
No sputtering just straight off. The unit randomly shuts off, could be just sitting idling after working for a few hours or 5 minutes after its started. i have tried to pin it down if rough terrain causing this issue and there hasn't been any commonality. Sometime the machine will fire right back up and other times it can take more then a few attempts to fire back up.
Have you replaced the stop solenoid?
 

Mark_BX25D

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Bx25D
Jul 19, 2020
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You need to monitor whats happening at the 12v input to the stop solenoid.

A 12 light bulb temporarily wired in parallel right at the stop solenoid will tell you what's happening.

You could do the same thing with a meter but that's harder to monitor while you are driving.

Stop throwing parts at it! TEST!

Forget about compression. Lack of adequate compression does not cause the sudden stop you have described.
 
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JohnR68

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F2400 Mowers
Dec 26, 2024
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QLD Australia
I'm having what i think might be a related issue with my FS3690 and Id certainly appreciate some tips. I went to start it this morning and forgot to have the parking brake on so it wouldn't crank. But then I impulsively hit the brake pedal before id released the key from the start position and the starter momentarily cranked. After that it wouldn't crank at all. I thought I might have damaged the brake switch contacts by making it under load when i pressed it with key in crank position. But Ive tested it and it seems good. I also tested the other two switches, seat and PTO, and they seem good as well. However after testing the switches and re connecting them I'm now getting what seems to be an alarm, the horn blaring constantly and a red light on the panel whenever i turn on the ignition. I don't have a wiring diagram for this thing and I can see one in the wiring diagram thread, but if anyone can provide any insight into the electrical system for these that would be great.
 

JohnR68

New member

Equipment
F2400 Mowers
Dec 26, 2024
3
0
1
QLD Australia
I'm having what i think might be a related issue with my FS3690 and Id certainly appreciate some tips. I went to start it this morning and forgot to have the parking brake on so it wouldn't crank. But then I impulsively hit the brake pedal before id released the key from the start position and the starter momentarily cranked. After that it wouldn't crank at all. I thought I might have damaged the brake switch contacts by making it under load when i pressed it with key in crank position. But Ive tested it and it seems good. I also tested the other two switches, seat and PTO, and they seem good as well. However after testing the switches and re connecting them I'm now getting what seems to be an alarm, the horn blaring constantly and a red light on the panel whenever i turn on the ignition. I don't have a wiring diagram for this thing and I can see one in the wiring diagram thread, but if anyone can provide any insight into the electrical system for these that would be great.
I figured out the issue, or two separate issues, one might be relevant to the original posters question about the machine randomly stopping. I think when i was testing the switches I've shorted something out because i found a blown 5 amp fuse. After i replaced that the constant horn/alarm stopped but still no cranking.

I'm only a little guy, 63kg (138lb), and it seems like i'm not heavy enough to always activate the seat switch. Up until yesterday I was always sitting on the front edge of the seat, because it was seized in the furthest back position and i never had the cranking issue. But yesterday I got around to freeing up the seat sliding mechanism and moved it to a more comfortable position for my short legs. Now when i'm sitting further back in the seat the switch doesn't always seem to activate. For the guys who were having the intermittent stopping issue, could it be that the mechanism for triggering the seat switch is somewhat temperamental and its switching itself off at random times depending on your sitting position?