L3540 hydro power questions

[hunt4570]

I have an L3540 Hydrostatic 4 wheel drive tractor, have had it maybe 8-9 years. This problem seems new or has been slowly getting worse and I'm just starting to notice it.. When I have a mower on and either going on flat land or downhill it seems to be fine, BUT on even a slight upgrade I seem to lose power and RPMs pretty bad! I thought it was due to running the finish mower as it seems to take more power than a brush hog, but using the brush hog yesterday it seems the same. I do not use this for business just maintaining my own property so not a ton of hours, bought it with 320 and now has fourteen hundred something. Did the hydraulic oil and filters last year and it just had a recent oil and filter change. Thought maybe it was leaking trans fluid, but I checked, and it was full and crystal clear. Any Ideas before Ie to drag it to the dealer???

 

[rScotty]

Nice photo...
Well, there's really no good reason why a tractor that young would have any change in power. My guess from what you say is the HST is fine. But before taking it to the dealer, I'd want to also make sure that the engine is up to power. Mostly that is going to be fuel and air filters, maybe check the valve clearances, and that the exhaust is not full of carbon. One of ours was down on power from a fuel filter that needed changing.

I mention the exhaust because yours is like mine in being right at the age that saw a changeover from the old interim Tier IV EGR emissions control to the newer full Tier IV emissions with regeneration.
I prefer the older type EGR emissions, but some Kubotas from that era have a pre-muffler that needs to be cleaned or replaced from time to time.

In choosing a dealer for something that is this vague, I'd want a real dealer with an experienced mechanical shop. I had a shop. The shop mechanic is going to need a dynamometer for sure, and either a hydraulic test stand or at least some hydraulic gauges.
Otherwise the mechanic is just guessing, and we can do that here for free.
rScotty

 

[JWR]

Have you made sure the air intake path is 100% clear? My first guess is that air intake is being restricted somehow. Next guess would be fuel flow restriction. Filters and all that...

 

[Chewwy]

Had a similar problem with my L3240 HST. It an inconsistent problem.

Check you fuel filter. Mine had some jelly like substance in it. Replaced it and problem went away.

 

[hunt4570]

Nice photo...
Well, there's really no good reason why a tractor that young would have any change in power. My guess from what you say is the HST is fine. But before taking it to the dealer, I'd want to also make sure that the engine is up to power. Mostly that is going to be fuel and air filters, maybe check the valve clearances, and that the exhaust is not full of carbon. One of ours was down on power from a fuel filter that needed changing.

I mention the exhaust because yours is like mine in being right at the age that saw a changeover from the old interim Tier IV EGR emissions control to the newer full Tier IV emissions with regeneration.
I prefer the older type EGR emissions, but some Kubotas from that era have a pre-muffler that needs to be cleaned or replaced from time to time.

In choosing a dealer for something that is this vague, I'd want a real dealer with an experienced mechanical shop. I had a shop. The shop mechanic is going to need a dynamometer for sure, and either a hydraulic test stand or at least some hydraulic gauges.
Otherwise the mechanic is just guessing, and we can do that here for free.
rScotty

Thanks, my dealer here has been very good to me over the years.

 

[hunt4570]

Have you made sure the air intake path is 100% clear? My first guess is that air intake is being restricted somehow. Next guess would be fuel flow restriction. Filters and all that...

Thanks, but it's been a little while sense I have checked, and I will do that!

 

[hunt4570]

So I'll check fuel and air filters this week, thanks guys and I'll let you know what I find out!

 

[hunt4570]

I replaced air and fuel filters yesterday, nothing seemed different just driving it around, if it ever quits raining, I'll hook a mower up and check it out.

 

[rScotty]

I replaced air and fuel filters yesterday, nothing seemed different just driving it around, if it ever quits raining, I'll hook a mower up and check it out.

Does the L3540 have a fuel lift pump? I just replaced that on our JD which had a problem running out of power at high revs.
I also used an air compressor to shoot air back down the fuel line to clean out the pick up fllter in the fuel tank. With the filler cap off I could see it bubble, so that line was clear.

 

[hunt4570]

Does the L3540 have a fuel lift pump? I just replaced that on our JD which had a problem running out of power at high revs.
I also used an air compressor to shoot air back down the fuel line to clean out the pick up fllter in the fuel tank. With the filler cap off I could see it bubble, so that line was clear.

I have no clue about the fuel lift pump but since my fuel tank is above the engine I doubt it. I'll have a look at the manual, thanks. Where did you detach the fuel line to blow it out?

 

[rScotty]

I have no clue about the fuel lift pump but since my fuel tank is above the engine I doubt it. I'll have a look at the manual, thanks. Where did you detach the fuel line to blow it out?

I detatched it right at the lift pump... but if yours does't have a lift pump it would be at the inlet to the fuel filter. I didn't want to damage the line to the tank or loosen the fittings, so I used real low air pressure and held the air nozzle by hand loosely in the fuel line.
With a flashlight I could see in the fuel tank that the pickup was bubbling like crazy so that saved me from having to take that line and filter out. I then used air to check the tank vent too. Mine has two vents. One on the tank and one in the cap. Belt and suspenders....

Even though the fuel tank is above the engine, any engine might still have a fuel transfer pump.

Another thing that can restrict fuel flow is if yours has a solenoid fuel valve to turn off the fuel when the run switch is off. And I'll bet it does have that. Those are known to go bad.

Again, the symptom of diesel fuel starvation is it may idle and work OK - but if you throttle up, it eventually runs out of power and will even die. Restarting can be easy or difficult...depends on if air gets into the system..

 

[hunt4570]

I detatched it right at the lift pump... but if yours does't have a lift pump it would be at the inlet to the fuel filter. I didn't want to damage the line to the tank or loosen the fittings, so I used real low air pressure and held the air nozzle by hand loosely in the fuel line.
With a flashlight I could see in the fuel tank that the pickup was bubbling like crazy so that saved me from having to take that line and filter out. I then used air to check the tank vent too. Mine has two vents. One on the tank and one in the cap. Belt and suspenders....

Even though the fuel tank is above the engine, any engine might still have a fuel transfer pump.

Another thing that can restrict fuel flow is if yours has a solenoid fuel valve to turn off the fuel when the run switch is off. And I'll bet it does have that. Those are known to go bad.

Again, the symptom of diesel fuel starvation is it may idle and work OK - but if you throttle up, it eventually runs out of power and will even die. Restarting can be easy or difficult...depends on if air gets into the system..

" Again, the symptom of diesel fuel starvation is it may idle and work OK - but if you throttle up, it eventually runs out of power "
That does seem to be my problem. I'll do some more looking, thanks!
And also only seems to happen mostly on a uphill grade.

 

[rScotty]

" Again, the symptom of diesel fuel starvation is it may idle and work OK - but if you throttle up, it eventually runs out of power "
That does seem to be my problem. I'll do some more looking, thanks!
And also only seems to happen mostly on a uphill grade.

"...happens mostly on an uphill grade."

A lot of tractors are overgeared in high range and can barely pull full RPM on the flat in road gear. So even if it is running perfectly, lacking power on a slight uphill is common.

But, when you are going uphill and notice it is suddenly losing power quicker than it once did, that's the classic first symptom of fuel starvation. The good news is that simple fuel starvation won't hurt the motor, and it sure is better than the other problems you were worried about originally.

 

[hunt4570]

"...happens mostly on an uphill grade."

A lot of tractors are overgeared in high range and can barely pull full RPM on the flat in road gear. So even if it is running perfectly, lacking power on a slight uphill is common.

But, when you are going uphill and notice it is suddenly losing power quicker than it once did, that's the classic first symptom of fuel starvation. The good news is that simple fuel starvation won't hurt the motor, and it sure is better than the other problems you were worried about originally.

It, I believe, has been a slow progression to this point, not like an overnight change, has kind of snuck up on me. Sometimes when I'm mowing my field, a large oval, on the long flat sides its doing fine, but at one end going up as I'm turning around sometimes I have to almost stop the tractor to let RPMs build back up.
The line above is EXACTLY what it seems to be doing.

 

[hunt4570]

So I have 2 small fuel lines that run from the top of the tank to the filter assembly and was going to try to blow them out. When I pulled one I got a strong stream of fuel coming from the filter where I detached it, plugged the hose back in and went to the connection at the top of the tank. I unhooked both those lines and blew into them but all I could hear from the tank was air blowing in and no bubbles so I'm thinking they were both some sort of breathers/return lines. I've looked through my shop manual and the internet and cannot find a schematic of the fuel system!! I'm guessing there is another line somewhere feeding the filter but can't find it with all the stuff in the engine compartment.. more searching/researching today....
Tracked this down at messics

Kubota L3540HST-3 (Hydrostatic Transmission/Rops / 2010 -) Parts Diagrams

Kubota Parts Catalog Lookup. Buy Kubota Parts Online & Save!

www.messicks.com

Ok, I can't get the right screen to load here, If you click the "Category box and go to Fuel system then click the diagram box and go to fuel pipe and fuel filter it shows the correct hose attachment on the bottom right of tank. I'll be checking this out today!

 

[hunt4570]

Ok, got the right line this morning, blew through it and could hear the fuel tank gurgling, Still even without a mower I cannot get to 2500 rpm going up hill.
Any other ideas?

 

[jonsstihl]

it sounds fuel related, at 1400 hrs you are coming up on the injector checking at the dealer. Injection pump check is at 3000 hrs I think. Have the valve clearances been checked? that is supposed to be at 800 hrs.

 

[jonsstihl]

what does the fuel filter look like. I know you replaced it but any chance it is some kind of sludge in the fuel making it plug faster. If you are draining the tank to clean it out that is one step required when you check the valve clearances, at least on my 4740 it is easier to access with the tank removed.

 

[hunt4570]

Valve clearances have not been checked, difficult to do?
Fuel filter looks fine, the one I replaced was not that old and looked good also.

 

[hunt4570]

Just talked to my dealer about my problem, he is also pushing the fuel as a problem as well. He did not think the valve clearance would be the problem. I told him I had changed the filter and blew back through the tank and it was still doing it and he was a little perplexed. He thought I should drain the tank to see if there was something in there falling back down onto the screen and re-plugging it so I think that is my next move, I really don't want to load it up on the trailer and take it in if I don't need to.