Kubota F2560 losing power

[JOESCDP]

This is a very long post regarding my F2560 that loses power after running for a period of time. I have tried to diagnose this problem the best I can as I was an accountant by trade and a golfer by choice:

I have a Kubota F2560 that I bought used with 750 hours, it now has 970. For the first year it ran and cut perfectly, then this problem started where the engine would lose 90% (estimate) of its power after about 15 minutes of mowing. This problem has gotten worse so I need some help before I take it to a Kubota dealer. I have maintained the mower with all engine oil and transmission oil and filters replaced per schedule. There are no signs of oil in radiator to suggest a head gasket problem.

Let me list the things that I have done to try and fix the problem:

Replaced the air filter, cleaned all aspects of the air intake system, I used compressed air to clean the radiator. Replaced both the fuel filters (twice), replaced all the fuel lines and the return fuel lines, replaced the fuel rod in the fuel tank (when I took the fuel rod out of the fuel tank the tube was completely rusted. I believe this is the source of the orange debris in the fuel filter), replaced the fuel pump, drained the fuel tank and vacuumed the tank for debris. Replaced the fuel with new fuel and bought a new fuel cap.

Replaced all the fuel lines and when finished ran the mower for 1 hour; 45 minutes at full throttle with no apparent issues. 24 hours later I started to mow and the problem returned.

Replaced the fuel shutoff solenoid. Problem did not go away..

The problem seems to start when the PTO is engaged and the mower starts to move for a short period of time. It started 5 minutes after I replaced the shutoff solenoid today.

I did some further diagnostics. Started the mower and let it run for 30 minutes. No problem. Sat on the seat with the mower running at full power, no problem. I thought the safety switch on the seat might have gone bad. I shorted the seat switch wire and the mower ran fine for 20 minutes. Engaged the PTO with the mower sitting still and ran it for 20 minutes with no problem. Decided to try and mow. Engaged the PTO, the throttle was at full power, and pressed the drive pedal. I went about 30 feet and the engine started to stall as before. Parked the mower and let it cool down for about an hour. Started it up again and ran it for 30 minutes with no problem. Pressed the drive pedal (no PTO engaged) and drove about 30 feet and the loss of power situation began. So it appears that the drive mechanism or linkage is the culprit. Where do I look for the problem?

Any help would be appreciated.

 

[kuboman]

Generally what you describe turns out to be a fuel problem. Did you check or replace the electric fuel pump? Are you sure the tank is very clean on the inside?
The electric pump can be erratic so I would replace it . And then replace the fuel filters again.

 

[JOHNTHOMAS]

Generally what you describe turns out to be a fuel problem. Did you check or replace the electric fuel pump? Are you sure the tank is very clean on the inside?
The electric pump can be erratic so I would replace it . And then replace the fuel filters again.

I agree that it's fuel related issue. Sounds like above mentioned or something is in the fuel tank that may be floating around and when the machine moves it covers the outlet hole of the fuel tank and then when stopped it floats/moves away from the outlet hole.

 

[JOESCDP]

Generally what you describe turns out to be a fuel problem. Did you check or replace the electric fuel pump? Are you sure the tank is very clean on the inside?
The electric pump can be erratic so I would replace it . And then replace the fuel filters again.

If you check out my first post I have replaced every part in the fuel path and vacuumed out the fuel tank. I just have a hard time thinking there is something in the tank. I visually inspected it after I used the shop vac. Is there some sort of governor that could be broken?

 

[hghvolt]

Is the F2560 driven by hydraulic motors at each wheel? It sounds like you have some extreme loads coming from your drive line. I gather this from your comments about how long the motor runs fine until you engaged the drive pedals

 

[kuboman]

I find it unlikely that there is a problem with the actual injection pump. Explain vacuuming the tank. Unless the tank was removed from the machine it would be very difficult to clean the inside of the tank. Also for the fuel pipe to be rusted tells me there has been a lot of water in the tank.

Is the mower stored outside or under cover?

 

[4570Man]

I think it's fuel related.

 

[art]

For what you found in the tank, check it again!!!!

 

[JOESCDP]

For what you found in the tank, check it again!!!!

The mower is stored outside and covered. I replace the fuel supply rod. I cleaned out the tank and found that the old fuel supply rod was coated with rust. Since I think I have done everything that would be from the fuel tank supply to fuel tank return, for the moment, let's assume that is not the problem. What else could cause this problem? I appreciate everyone's help.

Joe

 

[Pete6114]

Fuel tank cap vent may be plugged up. Worth taking a good look at. Next time it shuts down on you after 15 Min, unscrew the cap and listen for air rushing in, and see if it'll start right up again.