Jerky throttle

D2Cat

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It has to be a hydraulic issue somewhere. The spreader on the back also won***8217;t lower or raise now. Also, turns out I don***8217;t have to work now! YeHaw yeah, the way Christmas Eve should go.


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Don't come here and ask for help and expect to get any with that attitude.


NOTE: Moderator Changed not allowed language
 
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North Idaho Wolfman

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What you have been trying to explain from the beginning is a hydaulic/HST issue.
It's not a throttle issue it's a HST control issue.
When you say jerky throttle you mean jerky HST control, and sticking HST control.
The pedal you push on the floor is not a throttle it's an HST control pedal.
If the unit is under warranty get it to a dealer because it's either broken something or has contaminated fluid in the system.
Start checking levels of the hydraulic fluid and then check the consistency of the fluid.
Later today I will pop back in and check on some things, I think that the HST control on that model is electronic will have to see.
MERRY CHRISTMAS!
 

Kubotasidewalkdude

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L3940 HST
Dec 6, 2016
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What you have been trying to explain from the beginning is a hydaulic/HST issue.

It's not a throttle issue it's a HST control issue.

When you say jerky throttle you mean jerky HST control, and sticking HST control.

The pedal you push on the floor is not a throttle it's an HST control pedal.

If the unit is under warranty get it to a dealer because it's either broken something or has contaminated fluid in the system.

Start checking levels of the hydraulic fluid and then check the consistency of the fluid.

Later today I will pop back in and check on some things, I think that the HST control on that model is electronic will have to see.

MERRY CHRISTMAS!


I’ve already established that it’s hydraulic...it’s never going back to the dealer. They charge way too much and don’t fix the problem half the time. Our mechanic will fix it and if there’s an issue he’ll figure it out free of charge lol...


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Daren Todd

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If the hydrostatic is electronically controlled. Then it may be as simple as moisture, snow, or gunk in a quick connect. ;)
 

coachgeo

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Looks like we are back on track. Keep us updated on the results of checking on potential wet Electronic issues.

Very time consuming but Another idea is to drain the hydraulic oil and take it inside to warmup. Get a bunch of clear soda bottles DRY and fill them up. Week later the water (if any) should have settled to the bottom. Carefully pour out the good stuff. Since yours is NOT milky (ALOT of water) then this should work to remove everything but micro emulsions which the tractors system is designed to handle.

Old WVO bulletin boards will have ton of ideas on dewatering oil.
 
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coachgeo

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Don't come here and ask for help and expect to get any with that attitude.

Moderator Changed not allowed launguage
Think the language was not directed at us. But at excitement for getting Xmas Eve off work. Least that is how I read it. (and edited it inside the quote)

Guess if there are enough hours on it it could be both Fuel and Hydraulic being affected by the cold.
 
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Kubotasidewalkdude

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L3940 HST
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So we just got a dumping of snow and decided to take the tractor out. Let it warm up for 10 minutes like usual and it drives no problem. Get to my first school, do the sidewalks no problem. By the time I’m at my next school, the thing starts acting up. I took a video of what it does but not sure how to send it in here. Basically, no matter how I step on the throttle, the Rpms go up and down. Just put a fresh tank of diesel in as well. I’m pretty puzzled as to why it runs great until it fully warms up...I ended up leaving it in the middle of the city because it’s so annoying to drive but hoping to get it in our shop tomorrow to have a look at it. Oh, and 4 of our plows just had to break down as well. No big deal in -30 weather with 30cm lol


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Daren Todd

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For a video, you need to post it to a hosting site such as YouTube. Then just copy and paste a link to video in your post here.
 

85Hokie

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I wish my friend.


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Doing a little more research ......this seems rather "interesting" :p

amazing what Kubota comes up with! And this is/was offered on the L3940

Three range with Hydro Dual Speed, a high/low power shift controlled by left-hand lever. Auto Hydro Dual speed allows automatic control to match load. Stall Guard maintains engine RPMs by reducing speed under load. HST Response Control adjusts acceleration rates. Auto Throttle Advance links engine RPMs to transmission, so that the throttle increases when speed is increased.

https://www.youtube.com/watch?v=wd68NOyC2QA
 

Kubotasidewalkdude

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L3940 HST
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Doing a little more research ......this seems rather "interesting" :p



amazing what Kubota comes up with! And this is/was offered on the L3940



Three range with Hydro Dual Speed, a high/low power shift controlled by left-hand lever. Auto Hydro Dual speed allows automatic control to match load. Stall Guard maintains engine RPMs by reducing speed under load. HST Response Control adjusts acceleration rates. Auto Throttle Advance links engine RPMs to transmission, so that the throttle increases when speed is increased.



https://www.youtube.com/watch?v=


Sounds about right lol. Top speed of 25 kph. It’s an awesome little machine and sometimes over powers our plow trucks.


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North Idaho Wolfman

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For clarity is the Engine RPMS going up and down or is the speed of the tractor going up and down?
These are two different issues, if it's just the RPMs of the engine are jumping up and down, take it off auto speed control and set the trottle and go.
If it a tractor surging issue (tractor physically speeds up and slows down) then its a hydro or hydro control issue, yes it can also effect the engine rpm's.
The fact that your having other Hydraulic issues makes me think that you have problem in the hydraulic system.
 

Kubotasidewalkdude

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Haha here’s a good laugh. I didn’t know what this was and I turned it, causing the three point hitch on the back to lock...



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coachgeo

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Haha here’s a good laugh. I didn’t know what this was and I turned it, causing the three point hitch on the back to lock...



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communication is a bit whacky here. Least your updating us though.

seems your saying above laugh solved problem in below

It has to be a hydraulic issue somewhere. The spreader on the back also won't lower or raise now...
 

coachgeo

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L225 w/woods Few Mowers & Back Blade, D722 in Motorcycle (Triumph Tiger), LMTV
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Southern OH
For clarity is the Engine RPMS going up and down or is the speed of the tractor going up and down?.....
in post 29 he says engine RPM

So we just got a dumping of snow and decided to take the tractor out. Let it warm up for 10 minutes like usual and it drives no problem. Get to my first school, do the sidewalks no problem. By the time I’m at my next school, the thing starts acting up..... Basically, no matter how I step on the throttle, the Rpms go up and down. ....
 

Kubotasidewalkdude

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L3940 HST
Dec 6, 2016
43
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Yeah, but in post #24 he says it’s definitely hydraulic.


I’m almost certain it’s electronic after researching. Our mechanic said there might be a way for it to be reprogrammed or something/re calibrated.


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Daren Todd

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I’m almost certain it’s electronic after researching. Our mechanic said there might be a way for it to be reprogrammed or something/re calibrated.


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When it acted up this last time. Did you try shutting off the auto throttle control and using the hand throttle to see if it made a difference?
 

Kubotasidewalkdude

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L3940 HST
Dec 6, 2016
43
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Canada
When it acted up this last time. Did you try shutting off the auto throttle control and using the hand throttle to see if it made a difference?


Yeah I tried everything. Makes no difference when the machine is at full running temperature. So weird


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