KT745 stalls when hot

[rmhayes1954]

Bad Boy zero turn with Kohler KT745-3031. Starts well with temporary choke (about 5 seconds then no choke). Runs strong for 20-30 minutes then starts to fail (both cylinders are dying). Surges briefly with governor movement (about 1 minute) then stalls. When it cools down, it's good for another 30 minutes or so. New spark coils last fall. New fuel pump this month. When surging, I can see there is fuel in the fuel filter (filter is a clear plastic case) so no blockage from the tank to the filter. Added a hose clamp to the vacuum line to the fuel pump. Tried HEET fuel dryer to remove any water in the fuel.

Earlier this year the muffler failed with a big hole in the outer shell. That exposed the fuel pump and carb to hot exhaust gas. Did that do any damage? New muffler ($318!!!) this summer.

Any suggestions? I have a new carb but have not installed yet. New fuel pump is installed but that did not help.

 

[Steve]

Sounds like overheating. Are all the shrouds in place and tightly fitting? Are the cooling fins clear of debris? Is the cooling fan in good shape? No blockage of air to the cooling fan? Does it have spark after it dies? Oil level is ok? Will it start on starter fluid after it stalls?


Also double check your valve lash on both cylinders.

 

[Duce]

Is your fuel tank vented properly?

 

[Shane¹]

I bet the fuel lock off solenoid on the bottom of the carb bowl is bad when it gets hot it closes the main jet if it will run on carb clean after it dies I would check that.

 

[rmhayes1954]

Sounds like overheating. Are all the shrouds in place and tightly fitting? Are the cooling fins clear of debris? Is the cooling fan in good shape? No blockage of air to the cooling fan? Does it have spark after it dies? Oil level is ok? Will it start on starter fluid after it stalls?


Also double check your valve lash on both cylinders.

THanks for the thoughts. Shrouds and Fan are in place and good. I check for mouse nests every year and the recently checked the fins - no blockage. Oil is OK. I have not tried to start on starter fluid - if it sits a few minutes and cools it will restart.

Set valve lash on both recently using 0.005 feeler gage.

I will check on fuel tank venting. I recently re-fit that vent line and maybe it is buggered.

 

[rmhayes1954]

I bet the fuel lock off solenoid on the bottom of the carb bowl is bad when it gets hot it closes the main jet if it will run on carb clean after it dies I would check that.

Good thought - I'll give that a look.