L3800 No start/blowing fuse

[TexasRedneck]

I’ve been a member a while and benefited from many of the topics here on the forum over the years. My first post is for some assistance with a no start. I searched and tried to read the wiring diagram but I’m doubting the wiring diagram I’m looking at is correct as I don’t seem to have the same number of slow blow fuses. Page 290 here https://www.kubotabooks.com/AutoIndex/index.php?dir=Tractor Owners Manuals/&file=L3800 WSM.pdf


Over the past few years, occasionally my tractor would blow the 30 amp slow blow fuse, (key/stop 30amp slow blow) usually when I came off the seat while operating and the safety switch would kill the motor. Slap another in and it would crank up.

Yesterday I moved it out of the shop on to the drive and when I went to crank it it blew the “key/stop” fuse and when I put a replacement in it immediately pops when i turn the key either to the on position or the glow plug position. It will turn over but no start.

I removed the fuel solenoid and bench tested with currrent and and tested with ohm meter and it seems fine. As a matter of fact while it was out it would still blow the same fuse.

No rat chewing (i keep the shop surrounded by rat bait stations) so I’m wondering what else to look at. Tractor is a 2012 but only has 350 hours on it.

There is a relay for that fuel solenoid that I’m going to track down and test. Any ideas or suggestions are very much apprecaited.

 

[North Idaho Wolfman]

Is this what your fuse panels look like?

 

[TexasRedneck]

Yes, precisely. It is the no 10 in the illustration 30amp key stop that keeps blowing.

 

[85Hokie]

Check carefully for a chafed wire - mice may have chewed, or a wire that has been pinched.

Somewhere the wire is grounding out.

 

[North Idaho Wolfman]

Yes, precisely. It is the no 10 in the illustration 30amp key stop that keeps blowing.

Ok let me do some more digging, because yes the WSM on KB's is wrong for the US version.

 

[Jim L.]

Is this L3800 an HST? Because the wiring is different than the non-HST, and both are covered in the WorkShop Manual.

To find the short, unless there is an obvious burn mark, could mean sectionalizing the harness(es) to fault isolate.

 

[TexasRedneck]

Shuttle shift. Non HST

 

[North Idaho Wolfman]

Shuttle shift. Non HST

Go in your profile and change it to L3800DT

 

[TexasRedneck]

Profile updated. Wish I could find the actual wiring diagram. The fact that its blowing when the key is turned to glow plug/preheat and when turned to ignition is a clue but hard to tell the wires in common without the diagram.

 

[TexasRedneck]

Well, got it fixed. Never could find the actual wiring diagram but found enough commonality that I made some educated guesses to guide me.

Pulled the fuel solenoid and bench tested it with 12V and with an Ohm meter, all checked out.
Pulled the dash and instrument panel and began to trouble shoot. Started with the ignition switch. All good. Started honing in on the relay for the fuel solenoid. Once I pulled the relay, it would no longer blow the fuse. So tested the relay on the bench. Tested good. Began inspecting the wire from the relay to the actual fuel solenoid and found that where the wiring is routed through the bracket where the fuel tank mounts I found a chaffed spot where it was grounding against that bracket. It’s a shame that Kubota didnt think of putting a grommet there to prevent chaffing. I repaired the wire, tested and got no blown fuse. Went and found a nice grommet to instert in the space and re wrapped it and put it all back together. Lots of drama for a chaffed wire.

Oh, and I was insistent that there was no mice damage. As I pulled the instrument cluster I found signs of a nest and was prepared to eat my words but there was no damage from chewing.

I’ll post a few pics here in a second.
Thanks as always for the willingness to lend a hand and hopefully this helps someone else down the road.

 

[TexasRedneck]

 

[TexasRedneck]

Check carefully for a chafed wire - mice may have chewed, or a wire that has been pinched.

Somewhere the wire is grounding out.

For the record….you were right, lol. Willful thinking on my part for a tractor with 350 hours on it not to have a wiring issue does not override basic logic and electrical theory. ;-)

 

[old and tired]

Thanks for the photos!!! Mainly so I can check on my tractor for possibly the same wiring problem. I don't have that problem but now I'll make sure I never will have that issue!!