Kubota L2250 not running smoothly

[TPAP6924]

My 1987 Kubota started running funny. I was running the tractor the last couple of days for about 6 hours. Then today after running the tractor for about 4 hours the tractor started sputtering. It sounded like the tractor was missing. I backed it into the shop and let it sit, then started it again. When I set it at a high idle it is not smooth like it used to be. There is some skip or delay in the idle.

Any help thanks,

Thomas

 

[North Idaho Wolfman]

Start by doing a fuel and filter change, you will also need to bleed the air out of the system before it will run.

 

[ru5tybike5]

After doing a filter change and bleeding the air from the system as was already suggested, start the machine and set the throttle where it seems to be missing the worst. Crack the injector lines one at a time while listening to the engine. The one that doesn't seem to change the sound of the engine when cracked is the cylinder that is missing. After you have found that swap that injector with the one next to it and run the test again. If the missing cylinder moves when you move the injector you know you have a bad injector. If it doesn't you start looking at the injector pump and compression.

 

[TPAP6924]

So i cleaned the air filter. Changed the fuel filter and bled the lines. I ran the tractor for three hours on a colder day and it ran fine. Then i ran the tractor today and it's having problems again about 30 minutes. It seems when the temperature gets half way it starts to sputter lose power and the eventually dies. I let sit about ten minutes and it had a hard time starting so i cracked the air bleed valve and it started. I shut the valve and ran the tractor again. When the temperature started reaching the mid range it sputtered lost power and died.

 

[North Idaho Wolfman]

A few things come to mind:
Check the vent on the fuel cap.
Check the bypass line (overflow) from the injectors.
Could be a failing lift pump, easy to pull and check.
Might be Injector pump failing, save this for last!
Pull the injectors and have them tested sounds like they could be failing when they get hot.

 

[TPAP6924]

My problem has become more repeatable. When I start the tractor it runs fine but when the temperature reaches mid range the fuel is choked off and the tractor dies. To get the tractor running again, I have to wait for the temperature to cool down and open up the air bypass valve on the side of the engine to get started.

Does this sound like the lift pump is getting to hot and doesn't pump fuel?

I have completely removed the tank and cleaned. Replaced the two return fuel lines, inspected the main fuel lines. Replaced the fuel filter. Replaced the shutoff solenoid.

 

[Daren Todd]

Are your intake fuel lines crimped or clamped? Crimps will and can loosen up over time. Clamps will loosen as well. It sounds like the intake fuel lines are allowing a little air to get in the lines. Especially if you bled the air out and it started right up again. I've seen a pin hole leak in the lines seal off when it's cool and then start giving issues when the fuel warms up


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