I'm stumped.

Mowing season is back upon us.

My 3-year old 50" 26 HP V-Twin Kohler Garden Tractor started but after running it wouldn't start again unless I let it sit for 20 minutes or so. I figured it was the battery so I bought a new one.

Same thing, even after an all-night trickle charge.

So today I figured I'd attach a volt meter and compare voltage before starting and again while running. But today it wouldn't start at all. Showed 13+ volts before I tried to start it. Sounds like the battery because it's not turning over.

Any ideas?

Getting the solenoid click? Could be a safety lockout if no click

Take the battery cables off and scrub em up with a wire brush especially on the inside, could be corrosion. Does it have a kill switch for when you get up out the seat. Make sure nothing like grass has wedged in one of the contacts. Did it to me like that one time, I had mowed down my okra and one of the stalks had wedged up into the switch. You've got some contact that is short circuited.

I know this sounds simple but check to make sure you pushed the blade button down. Pull it up and push it back down several times.
One other thing to look at is the starter, make sure there is nothing hung up on it.

Check under seat for fuse, follow the wires.

Make sure the gas cap is venting. Sounds like it could be a problem if it runs for a bit and then dies. Just loosen the cap and see if it works.

You might tap on the started/solenoid area with a hammer and see if that kicks it in.

Are you using last year's gas ? (Stupid question, I know, but if so, sludge could have got down into the jets)

Thanks for the replies. I've tried all of those things except tapping the solenoid.

Looks like I'm taking it to the local lawn mower repair guy.

You said you bought a new battery. Does the solenoid click, and the engine try to turn but only moves a small amount? If so, the compression relief is defective. Can you keep trying the starter and eventually it turns freely?

Yes to the solenoid clicking and trying to turn over, no it never spins freely.

I bet it is the compression relief. Mine does that but I keep trying and after ten or twelve "clicks", it will spin freely and start. Or I can turn the engine by hand a half round and it will start normally.

I would pull the spark plug(s) and see if it will turn over. Look to see if liquid blows out of the holes, also check you oil for gasoline in it.
If it doesn't turn over I would suspect you stater is bad. Either the bendix or the bushing may be broken or worn out. I would also check the voltage at the starter.

Did you ever get it started?

No, not yet. Well once, but then wouldn't start again. Tried almost everything suggested here. I have it on the trailer now to take to my local lawn mower repair guy. Thanks for the replies.