Interesting, since the LX178 came with a Kawasaki engine?

I'd check the connector to the ignition switch and the (probably Red) wire from the B terminal on the ignition switch to its other end on the large starter solenoid stud that the battery + cable connects to.

What you are describing is exactly what would happen if you raised up off the seat (except for the wait 15 minutes part). I would replace the seat safety switch and rule that cheap part out as a source of the problem. it's easy to do yourself as it just plugs in. That not turning over part is a clue it's safety switch related.

Opps. I make a mistake, it is a KOHLER 15HP Engine, not a Kawaski.

Actually, you already said it was a Kohler in the first post. I think you make another mistake. I would say it is the fuel cap vent being plugged, but I would think it would sputter then die, might check by unscrewing the cap next time it dies and see if it will start. Intermittent issues are the worst to figure out.

We also can't be sure if the terminology used in the O.P. is "technically accurate" or not. You state, "Mower will not turn over or even try to turn over." This would correctly mean that the starter is not engaging at all, but some people incorrectly use the term to mean that the engine spins (with the starter) but does not try to "fire-up and run". So..........does your engine stop, and then you get absolutely no sound or movement from the engine when you turn the key to the start position? Or....does your engine stop and then it will just spin and spin when you turn the key to the start position, but will not even sputter or otherwise act like it wants to start? If you will clarify this, it will be easier to figure out whether your problem is in the "CRANKING" area, or "IGNITION" or if it is "FUEL". And a definite identification of Kohler vs. Kawasaki would be good too.

Sorry for the confusion:
The engine is a Kohler 15HP.
The engine will start easily, run and mow for about 15 minutes and then shut off as if the key was turned off. Then the engine will do nothing when trying to restart. When I say it will do nothing, I mean NOT A SOUND MADE. The engine will not turn over, the starter does not turn, or anything ... totally zero. Then after about 5 minutes of waiting, the turn of the key will turn over the engine, and it will start up and run perfect for about another 15 minutes. Hope this helps. Sorry again for the confusion.

The problem will disappear after Halloween night! Bet on it!

Your lawn tractor has three, maybe four, safety switches: each of them, if defective, has the ability to make your tractor seem dead as a rock.

Try to start your tractor while standing beside it: nothing will happen.

Try to start your tractor without pushing in the brake: nothing will happen.

Try to start your tractor with the PTO engaged, and again, nothing will happen. Well... you might hear a click.

All of these safety switches are wired into the ignition and, in effect, when activated, turn off the ignition, and "save you" from making a dumb mistake.

They will do the same thing when they go bad.

If you can get on the tractor, push in the brake, and you know the PTO is off, and you turn the switch and try to start the tractor, and nothing at all happens, not a sound, nothing! that tells me the switch is not working at all (or the battery is dead, but in this case you know it is not).

The ignition switch has been disabled.

Do the headlights work when exhibiting the problem?

Weird thing is that switches are not normally "time related" failure things. I normally don't jump to things like this, but a bad relay on the circuit board could cause that. But I'd check a bunch of things before buying a new one. Check the fuses.

By the way, a LX178 was a Kawasaki L/C twin and hydro trans. The LX173 was a Kohler and it had a 5spd gear drive. You may have a weird repowered tractor or a mix of tractors there.

bringing this back from the dead but mine does the same thing. anyone else able to figure out what the problem was?
...and i don't think it has anything to do with a faulty seat sensor...kinda ridiculous that that might be the problem

SOUNDS LIKE A OIL PRESSURE SAFETY SWITCH TO ME.IF IT EVER GETS TOO LOW ON OIL,IT WILL CUT THE FUEL OFF AND KILL THE ENGINE

My LX 178 runs for 30 min or so and then starts sputtering and then quits. Acts like it is out of gas. After 15-30 min will re-start and run ok for awhile. A mechanic suggested a failing diode under the hood may be the fault. Other suggestions could it be the fuel pump getting vapor locked?

first thing I would check is a blocked up air vent in the fuel tank cap . Run a paperclip up in it and then blow thru it to clear & try..

Vapor lock will not occur WHILE an engine is running.Vapor lock occurs when an engine is shut down in a very hot condition and heat from the engine cause a portion of the gasoline in fuel line and fuel pump to vaporize. The heated vapor exerts more pressure than the fuel pump can deal with and so the pump can't work, until things cool off and the gasoline vapors return to liquid.
You can test the fuel cap idea by removing the cap when the engine begins to falter. If it straightens out the running, the cap vent is the trouble.
If not, then it may be ignition related.

LX178 fuel problem mine seems to run out of fuel while mowing( shuts off) have to prime to restart ,Fuel filter is empty. Replaced fuel pump,carburetor,and fuel line back to the tank, actually drilled 4 small holes in gas cap( I have another one) to alleviate and vapor lock, any help would be appreciated .

Actually kmb1966 you are correct the lx178 came with a Kawasaki liquid cooled engine. The most likely also made one with a kohler however i think the liquid cooled Kawasaki is hard to beat!!!

my moms LX178 with the water cooled Kawasaki started dying after a few laps mowing then restarts after a few minutes then dies again, then it let me mow the yard, replaced the filter and took carb off and cleaned it wasn't really dirty at all and filter seems full by sight when it dies been a great mower any ideas fuel pump is $144.