Kohler hot re-start problem

[elderone1]

Cub Cadet LTX 1142 with Kohler Courage 19 HP SV470-620 engine. Two years old with 87 hours on it. Problem started about a year ago. Lawn tractor cold-starts and runs without a miss. If I stop it and re-start within a few minutes, it works. If I leave it off for more than, say, 15 minutes it will not start....not a hint of firing. Not until the next day, when it will start and run normally. After a couple of times when I had a load of firewood or branches and leaves in the dump cart away from the storage shed and having it not start, I have since just left it idling while I raked, bucked or shovelled. Idles and runs faultlessly for hours.
I checked and fiddled with the brake, seat and PTO interlocks. The spark plug is cleaned and wire-gapped to 30 thou. I put a momentary push to open switch in the oil pressure sensor to monitor circuit (no effect). Another "Ask" website expert gave up.
I think something gets overheated from stored engine heat when the rotation of the coooling fan stops. But what? Is there a condensor somewhere in the magneto circuit that is heat sensitive?

 

[Rivets]

We have to find out if it is a fuel or spark related problem. I am leaning toward spark. Next time it happens check to see if you have spark. If you have spark I am wrong (the first time ever) and we will address the fuel problem. First thing on a fuel problem is the check to see if the pump is working under hot conditions by removing the fuel line going to the carb and turning the engine over. Hopefully you will see fuel and we will go to the next step.

 

[elderone1]

I forgot to add: Occasionally (like today, two times) on a hot start after longer than 15 minutes, the engine fires-up immediately and dies within a second or two. If I am lucky, after a few seconds cranking, it will run. Most times, no amount of cranking, 8 to 10 seconds at a time, will get it to start again, until the next day.
This engine, otherwise, when it starts, it runs as soon as it starts with no misses or hesitations.

I guess checking for spark is a two person job? First the plug is buried deep in the cooling shroud. Second, someone has to sit in the seat and also depress the left (brake) pedal and turn the key to get the starter to connect. I'll have to get my wife involved!

 

[SONOFADOCKER]

Are your fuel lines dry or brittle ( sucking air ) is the carb bolts tight and manifold boats tight ?
Pull the plug out and look at the cylinder top with a light - look for carbon build up .
If the cylinder is dirty the carbon is hotter than the spark plug spark . As soon as the fuel is going into the cylinder it is burning before compressing stroke reaches top dead center .
It will not start until its cool .
That's why you have spark and a wet plug ...
Many machines come into the shop with the head loaded with carbon .

 

[Rivets]

Just put it in park and you should be fine.

 

[SONOFADOCKER]

Seat safety can be tricked by bungy cord or 5 gal pale with water dirt or sand in - I use a pale filled with spare tools - very heavy .

 

[elderone1]

I removed the spark plug this morning. It had a very low coating of carbon. I ran fine emery through the gap and checked the gap with a wire gauge; confirmed to be 0.030".

I'll look at fuel lines, carb. bolts, etc tomorrow. The unit is only 2 years old and has been stored in a well ventilated shed.
Thanks so far, but no Eurekas!

 

[elderone1]

Checked carb bolts...tight. Fuel line in good shape, as expected for a relativel;y new unit.

What about that "anti-afterfire" solenoid on the bottom of the float bowl? I see some posts say I should here a click when I turn the ignition key to the run position. I hear nothing.

 

[Rivets]

Grab it with one hand and turn the key on and off several times. Not all the way to start. You should feel it moving.

 

[elderone1]

Held the solenoid body and turned key on-of several times, just to "run" position.......nothing!

Any recommendations for next step?
I presume I should disconnect and remove it from the float bowl. There is no fuel shut-off valve, and the tank is full. I guess I have to remove the connected tube and lift it high enough not to siphon out? Minimize gas all over!
Instructions say replace fuel filter every 100 hours (not there yet) but they don't say how. Maybe there is enough loose line to raise it up above tank level, and that will allow removal of anti-afterfire solenoid

P.S. - Thanks to advice to "test & start in park". I feel dumb....I use park all the time, but store the tractor without setting park. I just never tried starting ir unless I was in the seat!!!!