Snow L3400 HST starts but won't run in cold weather

[k0ua]

Ok guys why are we heading off into safety switches and Hydrostat problems when the OP has stated:

.

Today, I put the tractor in neutral and reved the engine and the tractor immediately stalled.

you have to read this fellow carefully, as he is all over the map with this problem. He is attempting to describe this the best he can, but he is obfuscating the problem with all the extra information.. take it one step at a time.. When he opens the throttle the engine stalls, WITHOUT stepping on the HST pedal, or squirming in the seat. Of course the tractor stalls when he applies load by applying pressure to the hydro pedal, but that is a symptom NOT a cause. There is nothing wrong with any switches or hydrostat.. This is a fuel delivery issue, when the engine is cold. He has water, or crap or a big ice cube somewhere in the tank. Because as noted above when he is in neutral and opens to throttle to rev the engine it stalls the engine.. The engine is starved for fuel. Unless I mis-understood what he said.

James K0UA

 

[Katahdin]

I'm glad someone else caught that, yeah, I'm also leaning toward a fuel issue and not an electrical gremlin.

This is the second problem I've read on this board this month about a problem with "winter blended" fuel in Vermont. Vtsnowedin had the other problem, maybe you guys are using the same fuel supplier.

I'd suggest draining your tank and filters and refill with fuel from your nearest Irving station, Vermont has these. Irving is a Canadian fuel company and they only produce winter diesel at their refineries north of the border. I figure if anyone can make good winter diesel its the Canadians. Yes, I've read local gas stations all use the same supplier, but I've only seen Irving trucks unloading fuel at my local stations and I've met another TBNer that is an Irving employee that'll back up that Irving sells its own fuel at its pumps. Irving Refineries are actually the closest ones to us northern New England states, the next closest refinery is NJ I believe, but maybe the fuel you're using came up from the Gulf states, who knows. Save the fuel you drained out for August.

 

[Chilly807]

There might be some miscommunication here.. if it's running out of fuel at any speed over an idle, it should miss and sputter a bit before it dies, not just abruptly quit. When northeastern said he "revved the engine", did he mean he depressed the HST pedal, or moved the throttle lever to a higher position?

I'm going to continue with the post as if the switch IS the problem, it could be restricted fuel flow but doesn't sound like it to me. When he said he could keep it from stopping if he released the pedal quickly enough, it sounds like an on-off problem more so than starvation.

I checked mine this morning, the switch operates as advertised in the service manual, although it's a bit "scratchy", as in it's not a definite, sharp off-on situation. Mine might be getting ready to keel over as well, the tractor works fine now though.

This pic explains the connections for testing the seat switch, your most likely test is the two outside pins. With you sitting in the seat, there should be a continuous circuit between these two pins. When you stand up it should go to an open circuit. As I said, mine tested ok on all the variations, but it's the lowest position of the switch that seems to be the trouble if that's it. I would think if it was the HST pedal switch you'd have trouble starting the tractor and that's not the case. If anything, it's doing what it's supposed to, which is telling the system that "the tractor is about to move, there had better be someone in the seat". It may be slightly out of adjustment if you can inch the tractor ahead without it quitting, but not a lot.



The second pic is a (painful) translation from Japanese how the system works.. might be helpful? Sorry about the orientation, it appears upright in my photo editor, but here, not so much..



Third pic is an overview of the wiring diagram for the HST model. I'm not great at reading these, but maybe someone else is.



This shows the meter connection to the outer two pins, should be continuity with weight in the seat, open with no one in the seat.



Last pic shows the tab welded to the seat that operates the switch. Mine was slightly bent upwards when I got the tractor, it would cut out (shut off) when I went over a small bump, I had to bend it down a bit, no more than 1/8 of an inch was enough to do the trick. If you suspect this to be a problem, easy way to check is to tape a thin piece of something to the bottom of it and try it, maybe a piece of paint stir stick??



At the end of this, please be sure the switch is working normally, in other words if you're not in the seat and you press the HST pedal, the engine should stop immediately. Same with the PTO being engaged, if your weight is off the seat and the pto is engaged, the engine should stop within 3 seconds unless you flip the seat ahead. I hate troubleshooting this stuff, if it gets fixed "temporarily" and some one gets hurt by it down the road because it was never actually repaired, you always feel a bit of responsibility for what happened. If you feel you're in over your head, a good dealer service dept can probably sort this out pretty quickly.

Anyway, good luck with it!

Sean

 

[Chilly807]

So.. fuel issues.. first I'd like to say that Canadian diesel had better be good.. we charge enough for it up here. Last time I looked it was $5.30 for a US gallon. Glad my tractor is no bigger! It's possible that the fuel shut-off solenoid is shutting the engine down for some reason (crossed wires, a short circuit maybe), but that would be Twilight Zone strange.

The reason I'm leaning toward electrical is A: I don't really trust anything with wires on it (try wrapping a wire around a hammer sometime, it'll never drive another nail!) B: the abrupt way it shuts down. If it was fuel starvation I think it'd be slower, missing, then stopping. Does it restart immediately, without any abnormal amount of cranking? Just moving the tractor doesn't take much more fuel than idling, not like it's being worked.

Another check is to loosen the fuel filter bowl with a bucket under it, if fuel flows freely there's no ice in the tank or lines down to the filter. One thing to note, there's a fuel shutoff valve in the rim of the filter housing, so if you turn it out too far fuel will stop, you want to turn it just enough to get the bowl off the gasket. He's used 911 a couple times, and the tractor starts and runs, so it should be through the system. I think he said it ran for an hour or so? Might be wrong on that.

Hopefully it's not frozen solid to the ground and the engine can't move it I've seen that happen before, but it's usually up to the rims in frozen mud for that to happen. The other possibility is water in the HST transmission or valving, really hope that's not the case. Unless the fluid is really old or water's getting in somewhere it's unlikely. I've never heard of that happening, other than the old Case and MF tractors where water used to go in through the shifter boot and freeze. I was paranoid about that when I got the Kubota, mine has a rubber disc over the top of the boot to prevent that if the boot ever tears.

Sean

 

[Katahdin]

Canadian diesel is a couple pennies under $4 gallon here, I presume the higher prices are due to gov't tax collectors not quality and demand!

For the engine rev test I assumed the seat switch was already defeated because the transmission would be in neutral and the parking brake set. On my Yanmar HST, under these conditions, the operator can stand on the ground beside the tractor and increase engine RPMs with the hand throttle. Would these test conditions also work on the Kubota?

 

[Northeastern]

So now I know why you guys pay all the extra $$$ to buy your brand?! For switches that keep the tractor from running...:laughing:
Yes, OP, follow what the guys who have Kubotas tell you when it comes to which two wires to jumper, OR first see if the seat switch connector has come loose, or a loose wire, or spring tab, BEFORE you disconnect it.

Today its 31 degrees out. The tractor started but wouldn't move AGAIN. I lifted up the seat and moved the lever on the safety switch. There was some resistance (like maybe some ice to break through) and then it freed up. Got back in the seat and the tractor runs! I know the lever will need to be adjusted (not sure if the nuts loosened or its just moisture freezing), but for now, I can at least plow my driveway and know that I will just need to free up the switch lever if it happens again.

Thanks for all the help, I couldn't have solved the problem without you guys!

 

[Northeastern]

Thanks for all of your ideas, I could not have figured this out without your help. The problem was the seat safety switch lever. It was stuck and once I freed it up, the tractor ran today. I wish I had a barn to keep the tractor in, but it is outdoors and there has been enough rain, sleet and snow blowing here that gets under the seat. Thanks!

 

[Chilly807]

From the looks of the wiring diagram, there's no neutral switch on the HST version of the L3400. Which means you can start it in any range as long as the clutch is depressed. As soon as you depress the HST pedal, it brings the seat switch into the loop, which looks for weight in the seat. Under those conditions, the only position of the seat that won't kill the engine is fully down with an operator in it.

The DT (gear) version of the tractor doesn't have a clutch switch, however the shuttle or range select lever must be in neutral before the starter will engage. In both versions, the PTO must be disengaged to start the engine.

At first I wondered about the lack of a clutch switch on the gear drive version that I have, then I realized it allows you to start the engine while you're standing on the ground as long as it's in neutral. Handy for warmup or running the hydraulics, but I still always check to be sure it's really in neutral before turning the key. You're standing right in front of a rear tire when you turn the key, so if the neutral switch isn't working you're in a world of hurt if it goes ahead. It's easy to develop bad habits, something you have to remember when you run somebody else's tractor.

To answer your question Katahdin, yes it should allow you to use the hand throttle, even if the transmission isn't in neutral since there is no neutral switch as far as I can see. You just can't touch the HST pedal. James (K0ua) had one of these a few years ago, he should be able to say for sure. I'm not sure if northeastern was using the hand throttle or pressing down on the HST pedal with the trans in neutral. If it was still dying using the hand throttle I'm at a loss as to what is going on, unless it's running out of fuel instantly for some reason. Being in neutral shouldn't make a difference if you press the HST pedal.

Sean

 

[k0ua]

Well I don't know for sure what is happening with his tractor, as he keeps making references to "stepping on the gas" and things like that. But I thought the I put the tractor in neutral and revved engine and the engine stalled, seemed pretty definitive to me. When he steps on the hydrostat treadle pedal If the engine is at idle and the engine is fuel starved it very well may die quickly by having a load placed on the engine. The number 1 problem with remote diagnoses is beating the information out of the informant. When I asked what happened when you run the throttle up to 2000 RPM and then press on the Hydrostat pedal, he did not directly answer, but his statement of opening the throttle past idle and the tractor stalled, seems pretty definitive to me. I take that to mean he cannot get the engine to achieve 2000 RPM to make the test I requested. Of course the use of the word "gas" just confuses the issue. There is no "gas" anywhere near your diesel fuel powered tractor. No gas pedal, no gas throttle, and you better hope like heck there is no "gas" in your fuel tank. If you keep speaking about "gas" sooner or later some kind meaning person is going to put some real sure enough gasoline in your tractor and you WILL be sorry.

 

[k0ua]

Well I can see my post was 5 minutes late and a dollar short.. glad you got it going.