F2560 Mower Losing Power

[JOESCDP]

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, used compressed air to clean the radiator. Replace both the fuel filters (twice), replaced all the fuel lines and the return fuel lines, replace 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.

I just 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 replace the shutoff solenoid today.

Any help would be appreciated.

 

[85Hokie]

"vacuumed the tank for debris"

could you have something in the tank.....that the vacuum did NOT get out?


Right after it happens again - pull the fuel line from tank if possible.......strong gravity stream? or weak dribble? Then do same after the fuel pump, somewhere you have a fuel restriction.

 

[JOESCDP]

Removing the fuel line from the tank requires the remove of the entire chassis cover, Kubota refers to this as the fender, which takes about an hour to do. It seemed very odd that after I ran the mower for an hour without using the PTO or engaging the transmission that there was no problem. Does anyone know what happens when a "load" is placed on the engine that would signal more fuel?

 

[D2Cat]

You might pull the fuel line from where ever you can get to it as it come from the tank and give it a shot of low pressure air. Have the fuel cap loose or off. Then reconnect the fuel line and see it it makes a difference in the power of the engine. Maybe if there is some obstruction in the tank you can dislodge it long enough to confirm that is the problem.

That should give you a clue at to which direction to go.

 

[JOESCDP]

I will try that in a couple of days. I had tried that previously and it did not work.

 

[ttaylor61]

I had a similar problem with my BX. After heading down a similar path of chasing fuel problems a friend suggested it may be electrical. Found a safety switch going bad. Good luck.

Sent from my SM-T810 using Tapatalk

 

[JOESCDP]

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?

 

[1970cs]

Sounds like you have eliminated a fuel issue! I would go one step further and rig up a fuel can and hook it directly the injection pump supply line and see what it does.

If it goes on it's nose after that then I would be looking at the injection pump rack to see if it's fully stroking the injection pump. Then if that's ok, I would speculate a governor problem.

Pat

 

[JOESCDP]

Spoke with a Kubota mechanic today. He said there is a safety switch connected in the HST path, but I am having a hard time finding it.

The Kubota mechanic also said the problem might be electrical and not fuel related. Replace the controller unit in the steering housing and put in a new battery. Problem reoccurred 24 minutes after starting.

 

[JOESCDP]

FINALLY SOLVED (Please see my earlier post)
Before I go into details on what the problem was, I would like to thank all those folks that tried to help me out. Two of the suggestions were actually what solved the problem.

The problem was debris in the fuel tank that was not removed when I vacuumed out the tank. I had sent to Kubota all the details as they appeared in my posting and they connected me with Dennis Hood in Georgia who is the Kubota customer service rep. Dennis has been in the business for almost 30 years and took the time to discuss all the issues. He suggested using a “nursing” tank to try and see if it was an engine problem. This had also been suggested by a contributor to my post so I got an empty gallon water bottle, made the connections to the mower and gave it a go. The mower ran without a problem for over 3 hours and several gallons of fuel. Dennis thought the tank may have had contaminates in the fuel that would have left a deposit on the tank that would subsequently clog the fuel line. I removed the tank and dumped the contents in a bucket. What also came out was an accumulation of dirt, rust, and pine needles. I have no idea how the pine needles got in the tank but I got the same thing when I vacuumed the tank in the summer. I took the tank to a local car wash with a pressure wand and cleaned the tank for 15 minutes under high pressure. I let the tank dry completely, replaced the fuel rod with a single piece of stainless steel tubing and put everything back together. Bled the lines and the mower started right up. I mowed the entire 3+ acres in 90 minutes.

Hats off to all the helpful suggestions. The removal of the tank was actually just two nuts that held a strap around the tank, so it was much easier than I thought. As Dennis and other have said, “You need 3 three thing to get a diesel engine running, air, fuel and compression.” I hope that I can keep this mower going as long as I have had my B5200 going which will be 28 years next mowing season. Thanks to all for their help.