Kubota 125s begins to lose power after warm up.

I found a pair of modules\coils at a good price. They should be here saturday or sunday, or Monday.
I will update this post after I install and adjust the new parts.
Here's hoping.

Doc
 
Coil tricks

1.Remove small black kill wire from coil. This bypasses key switches and safeties FOR TESTING ONLY. If the coil is good, should run the tank dry. Note you will have to ground the plug wire out to kill the engine. Not a big deal for testing only.
2.Remove coil. Polish coil mounting pads ON the coil and the pads where the coil sits. Or make sure a ground wire is connected IF yours has a ground wire. Clean off all the corrosion and rust. Coils need a good ground to create spark.
3.Test coil with an open gap type tester at the plug wire end.
4.Recommend running non-resistor plugs for better spark.
5.Coil air gap normally is 0.008" to 0.010". Check YOUR engine manual for proper specs. Piece of junk mail between the coil is fine using the flywheel magnets to pull the coil against the junk mail and flywheel.

Sometimes the coil will start working again. Remember to reconnect the black kill wire to shut her down AT the key.
 
GRRRRRR!!! Both cylinders are working full time. BUT! The original problem still persists.

After about 30 minutes of mowing, it did the same thing that caused me to write in .
With the PTO engaged and moving the engine will lose power and almost die. IF I disengage the PTO it will settle back to an idle. If I do not disengage the PTO, but let the bars remain in the neutral position, it will level out as well.
Any attempt to move forwards or back, with the PTO engaged, will result in the engine losing power as if it is overwhelmed. If I insist on moving it will eventually die.
I can disengage the PTO , I can move as much and as fast as I want.
It does not need any additional load on the blades to cause this phenomenon. If I engage the PTO and put the deck on transport height, it will do the same thing after a few minutes.

I can allow it to cool for just a minute or two and I can once again mow for perhaps 60 yards and will once again act overwhelmed. Even if I just let it run sitting still at full throttle, for a minute or two it will work for a short distance before acting up again.

Help!
I do not want to take it in to the dealer. Cost too much, and
they tend to ignore a woman because we are ,,,,,,,,.

Doc
 
doc craker said:
GRRRRRR!!! Both cylinders are working full time. BUT! The original problem still persists.

After about 30 minutes of mowing, it did the same thing that caused me to write in .
With the PTO engaged and moving the engine will lose power and almost die. IF I disengage the PTO it will settle back to an idle. If I do not disengage the PTO, but let the bars remain in the neutral position, it will level out as well.
Any attempt to move forwards or back, with the PTO engaged, will result in the engine losing power as if it is overwhelmed. If I insist on moving it will eventually die.
I can disengage the PTO , I can move as much and as fast as I want.
It does not need any additional load on the blades to cause this phenomenon. If I engage the PTO and put the deck on transport height, it will do the same thing after a few minutes.

I can allow it to cool for just a minute or two and I can once again mow for perhaps 60 yards and will once again act overwhelmed. Even if I just let it run sitting still at full throttle, for a minute or two it will work for a short distance before acting up again.

Help!
I do not want to take it in to the dealer. Cost too much, and
they tend to ignore a woman because we are ,,,,,,,,.

Doc
Click to expand...
To me, this sounds like the engine is starving for gas.

Blades are ultra dull and OR installed upside down.

Normally when a timed fault is noticed, THAT tells me there is trash in the fuel tank. Those dirt bag tank blobs bounce around and finally clog the fuel outlet in the tank. That starves the carb for fuel.

Next time she stutters, turn the choke on half way. See if power returns and engine smooths out. Choke on half or full will enrichen the fuel mixture.

Long shot on timed faults is a weak ignition coil failing on you. Need an open gap spark tester. One you can open or close the spark gap and stress test the coil.
 
Thanks slomo. let's take your ideas one at a time.

New in line fuel filter. When it first started this I thought the same thing. I also visually checked the clear filter each time it malfunctioned. Same level of fuel and filter is still clean.
If it is fuel starved, why wait until it has been running for an hour? Why get better after cool down period?

Blades are new. Installed properly. This started happening last summer near the end of the mowing season. So, I did some maintenance things in effort to find issue.
Including changing the hydraulic filters on the drive motors and new fluid, and yes, I cleared the system of air.

I can try the choke idea, and the gap tester. I didn't think about widening the gap to stress the coil. I did check the exhaust pipes when it happened. I even used the hose to try to cool down one pipe or another
to see if I lost a cylinder because the older coil heated up. Both stayed hot, so both were\are firing.

Misc items I changed out last fall.
Belt, I made sure the tension pulley and spring are both working as well. Man! That is one tough spring too! lol
Both spark plugs.
Fuel filter.
Fuel pump.
Starter solenoid. It quit.
Hydraulic filters and fluid.
Oil filters and oil.

As you can see, I am frustrated and confused. I do not understand the lack of power only after warm up.

Doc
 
I also think it's a fuel issue.
Is the fuel filter installed with the arrow pointing to the carburetor?
I noticed that you have a 2017 model. I would suggest replacing all of the fuel lies. There is a high probability that they are deteriorating on the inside.
 
doc craker said:
I also visually checked the clear filter each time it malfunctioned. Same level of fuel and filter is still clean.
Click to expand...
You can not see fuel FLOW simply by LOOKING at it. Only thing your test gave you was yes you see fuel there.
doc craker said:
why wait until it has been running for an hour? Why get better after cool down period?
Click to expand...
Again talking about a timed fault. I explained it on how this can happen. Trash in the tank. Leaves, bugs, dirt, bugs and any other physical item that does NOT belong there. If said trash makes it to the tank outlet, it will impede fuel flow to the carb. If you pinch a garden hose what happens? Less flow right?
doc craker said:
Both spark plugs.
Click to expand...
Where did you get these from? Only buy plugs from a LOCAL auto parts store. Plugs like many other items are pirated in China. Stay off amazon and evilbay for plugs.
doc craker said:
Fuel pump.
Click to expand...
Needs tested just like ALL of your new parts. New doesn't mean new these days. New means a must test to confirm they work.
 
Pull the fuel line off where is goes TO the carb. Drain in a glass jar. Look for water and trash in the bottom. Should have a solid flow out of this hose. Solid as in wow get a bucket quick.
 
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