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

art · Dec 27, 2013

art said:
A diesel without load might make it to full throttle with frozen or gelled fuel... Most times you can just look at the Kubota fuel filter and if it is white, it's froze. I would check the hydraulic fluid as well, if the tractor hasn't been run just loosen the drain plug. If nothing comes out then it is for sure frozen. You didn't say how old the tractor is and in the northeast with condensation issues I say two years max on the transmission oil if stored at or near outside temps. A diesel for good warm ups needs to be at 1/4 or 1/3rd throttle. A good hair dryer or paint stripping gun on the fuel filter and lines would go a long way is thawing the fuel system out!

k0ua · Dec 27, 2013

I for one do not understand your description of the problem. You mention giving the tractor more gas. What does that mean? Do you mean advancing the throttle to make the diesel engine increase RPM? Or did you mean pressing on the hydrostatic directional and speed control, the "treadle pedal"? There is no gas involved in either of these actions. Let me ask the question in another way, if you advance the fuel throttle to around 2000 RPM and then press on the hydrostat pedal to move forward, is that when the engine stalls ? Or is it when you attempt to advance the fuel throttle to run the RPM's up is when the engine stalls?

James K0UA

Coyote machine · Dec 27, 2013

I'll go one further: to the OP: please answer the following. 1. This is a diesel tractor with manual transmission?
2. When you say 'give it more gas' you mean increase the RPM by hand/foot using a throttle mechanism?
3. When you try to move forward or reverse describe EXACTLY what you are doing and what happens.

TSO · Dec 27, 2013

have you checked to make sure that the PTO switch or the seat safety switch are not frozen in place?

It may sound silly, but if everything else has checked out, then maybe that's the problem. With my HST, if I lift my weight off the seat while moving it will try to stall out before I get my butt back on the seat. From what you are describing, that would make sense.

Besides checking the switches themselves, also check the wires for damage, and the fuse.

beardley · Dec 27, 2013

TSO said:
have you checked to make sure that the PTO switch or the seat safety switch are not frozen in place?

It may sound silly, but if everything else has checked out, then maybe that's the problem. With my HST, if I lift my weight off the seat while moving it will try to stall out before I get my butt back on the seat. From what you are describing, that would make sense.

Besides checking the switches themselves, also check the wires for damage, and the fuse.

+1 on the seat switch. That would be my vote. My Seat freezes on my boomer and yanmar. They run great but the moment you try to move, it stalls like you turned the key off. Test the seat switch with a jumper across the pins.

Northeastern · Dec 27, 2013

k0ua said:
I for one do not understand your description of the problem. You mention giving the tractor more gas. What does that mean? Do you mean advancing the throttle to make the diesel engine increase RPM? Or did you mean pressing on the hydrostatic directional and speed control, the "treadle pedal"? There is no gas involved in either of these actions. Let me ask the question in another way, if you advance the fuel throttle to around 2000 RPM and then press on the hydrostat pedal to move forward, is that when the engine stalls ? Or is it when you attempt to advance the fuel throttle to run the RPM's up is when the engine stalls?

James K0UA

This is a 2007 Kubota L3400 HST. It runs like a top when the outdoor temperature is above 32 degrees. It ran perfectly on 12/22/13 when the temp was in the mid 30's. The tractor always starts no matter what the temperature and has a smooth sounding idle. What I have referred to as giving it the gas is actually, pushing on the directional foot pedal to go forward or in reverse; on cold days, it stalls and will not move forward. As I mentioned I added PS 911 at the amt recommended for the fuel in the tank thinking I might have a gelling problem or water in the tank. Seasonally, the disel mix changes and I am using winter disel now. Today, I put the tractor in neutral and reved the engine and the tractor immediately stalled. The fuel filter looks clean (replaced it when trying to solve this problem and even the old filter looked clean and had no signs of waxy build up or icing). Today, there wa no sign of gelling or icing visible in the gas filter. The FEL works even when the tractor won't run. It seems like the tractor is 'disel' starved when its cold. Any ideas?

wmonroe · Dec 27, 2013

When you press the hst pedal and it stalls, does it stall like the key was shut off or does it labor and stall like someone pulling out and stalling a manual transmission? It sounds like a seat/safety switch to me also.

dex3361 · Dec 27, 2013

Try to remove the fuel filter and open the fuel valve to check the fuel flow. You may have something partially blocking the flow. Also I have seen fuel filters wax off and I couldnt see it through the bowl but when I had the filter out of the fuel bowl I could scrape a coating of waxy goo off of the filter. I changed the fuel filter and all was good.

TSO · Dec 27, 2013

dex3361 said:
Try to remove the fuel filter and open the fuel valve to check the fuel flow. You may have something partially blocking the flow. Also I have seen fuel filters wax off and I couldnt see it through the bowl but when I had the filter out of the fuel bowl I could scrape a coating of waxy goo off of the filter. I changed the fuel filter and all was good.

I don't think it has anything to do with fuel flow. This is a HST. The tractor runs at a certain RPM, and spools the hydro pump to spin the tires. Pressing the GO pedal doesn't increase the RPM's so it's not a matter of being fuel starved all of a sudden.

It seems like it HAS to be something related to an electrical shutoff.

Coyote machine · Dec 27, 2013

One thing is for sure, until we get this nailed down to fuel or electrical problem were just spinning our wheels.
Try jumping the seat switch and see what happens as has been suggested. If nothing then post that so we can keep narrowing it down. It is possible, IF the issue is fuel related due to prior NON-winterized diesel getting gelled or some water having frozen, or both, that there is some residual gumming between the tank and your IP. I would try using a hair dryer to follow your fuel lines from your tank to your IP, trying to heat up any gel and to get it to flow to your current filter and beyond to your IP. Don't cook the lines, apply just enough heat to get any gelled fuel to flow to the filter....