Kubota 125s begins to lose power after warm up.

[doc craker]

Well,,,,,,,,,. Crap!

Trouble starting. Won't stay running. Have to use choke to start every time. Finally warmed up enough to stay running without choke, and, did what it has been doing all along.
Except, it does it right out of the gate.

So. Is this the working theory? The swollen restricted flow fuel lines allowed the, "not so good" fuel pump to let it start and run for a while. At least long enough to get warmer. Now, with the new less restrictive fuel lines the fuel pump cannot keep up?

I did what slomo suggested and pulled the fuel line from the carb this morning and there was just a little fuel in it. Not really enough to say the section of line was full.
What does that tell me?

I placed an order for a replacement fuel pump, and vacuum line.

What next?

Doc

BTW it did the slow start, warm up thing yesterday when I first tried after the new lines and filter. I just assumed it was the fuel lines and filter being empty and filling up. Guess not.

 

[doc craker]

I was wondering. Did I knock something loose during all that cleaning? Something clogging a jet? Is the float sticking?

I put stabilized fuel in it every fall and run it enough to get it into the engine, shut off the fuel and let it die.

It has had nothing but premium fuel since day one.

Curious.

Doc

 

[MParr]

I'm guessing that your Kubota is powered by a Kohler Courage Pro SV 740.

 

[slomo]

Have to use choke to start every time

Normal

Finally warmed up enough to stay running without choke, and, did what it has been doing all along.
Except, it does it right out of the gate.

What exactly is it doing?

The swollen restricted flow fuel lines allowed the, "not so good" fuel pump to let it start and run for a while. At least long enough to get warmer. Now, with the new less restrictive fuel lines the fuel pump cannot keep up?

Possible. That is why we've suggested pull the fuel hose off AT THE CARB INLET tube. Drain it into a glass jar. Crank the key. Fuel should be shooting out of the fuel line. If not, the fuel pump is bad. You said the tank is clear zero trash or restrictions. New fuel line and filter. Should be nothing to impede fuel flow OTHER THAN a weak or dead fuel pump. Could be the pulse line ON the fuel pump is cracked or not sealing resulting in the pump not pumping. Could be a 9 year old pump is tired or dead?? She wants more gas. Find out where and why you are lacking fuel delivery.

Remember on a new engine. Tank is spotless. Fuel lines are new and wide open. Fuel filter is clean. Carb is clean. She ran like a new engine should. Now 9 years later........

I did what slomo suggested and pulled the fuel line from the carb this morning and there was just a little fuel in it. Not really enough to say the section of line was full.
What does that tell me?

Is this the same as pull the hose of AT the carb inlet test? Did you crank the engine?

 

[doc craker]

What exactly is it doing?

what i originally wrote the post about. initially it would malfunction only after 45 minutes of running great. It would die when the PTO was engaged and i would try to move or turn.

This morning it did the same, just as soon as I started it instead of after an hour of mowing.

Is this the same as pull the hose of AT the carb inlet test? Did you crank the engine?

No, I did not crank the engine. I will do this tomorrow and see if it moves any fuel.

Could be the pulse line ON the fuel pump is cracked or not sealing resulting in the pump not pumping.

I wondered, it was flimsy and looked worn out. Have a replacement on the way with the new pump.

I will update after tomorrow.

Doc

 

[slomo]

initially it would malfunction only after 45 minutes of running great. It would die when the PTO was engaged and i would try to move or turn.

This morning it did the same, just as soon as I started it instead of after an hour of mowing.

So she starts and runs for say 45 minutes. Mess with PTO, engine dies. THIS is another issue I think. Possible PTO drawing excessive current, bad corroded or shorted wires maybe? Sounds like a safety is kicking in if it is killing the engine. Sounds like it is not blowing fuses.

To narrow down your issue, drive the hooptie around WITHOUT the PTO touched for 45 minutes. Don't touch the button. Go up and down hills if you have them. See how it runs and drives only.

I was thinking a fuel related issue loading the engine while turning on the PTO. Starving for gas under this suddenly applied load. THIS still could be possible.

For TESTING ONLY, one could pull the kill wire off the coil/s. This bypasses all safeties and should run till the fuel tank is dry. Assuming the ignition coils are good. Don't recommend someone doing this. Person could die from a mower accident. If someone did this, they would have to pull the plug wire off the plug/s to kill the engine. I'm sure IF a person was to do this, they would exercise caution.