Cat 259B3 Sputters, Blows White Smoke Only After Hours of Use

[Howey Matt]

Is the fuel tank venting? 3-4 hours would pull quite a vacuum on the tank. If it’s acting up still pull the cap off to check if it’s suctioned on

I'll check this next time it acts up, thanks!

 

[heymccall]

I normally turn the key to Run, which causes the pump to cycle for 4-5 seconds. Once it stops, I turn the key to Start and it cranks up. It won't do anything unless the lap bar is down.

Lap bar down and momentarily turn key to crank, then let go, back to run, and the priming pump will run continuous.

 

[Howey Matt]

I finally got the o-ring from the John Deere dealer and replaced it. New fuel filter, fuel tank drained and cleaned, etc. The white smoke cleared up and the machine seems to be running fine now. I won't know for sure if it's actually fixed until I run it a few days. Thanks to @Nige and @heymccall for helping me out with this!