L3540 hydro power questions

[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.