M-ZT 52 Stops running when hot!

Sounds like Coil going bad. Insulation breaking down with Heat. It's happened to me a couple of times with Briggs engines, they would last about 1/2 hour before quitting. New coil is the fix.

I'm betting on a fuel cap vent with asthma.

Gord Baker said:

Remove Fuel tank Cap and fuel line at filter. Blow back the line carefully with minimum pressure. Do this outside, off the driveway and don't be looking in the tank while you do it. Then blow the other direction using low pressure. If fuel flows OK, continue to removing Float bowl and be sure fuel flows with float raised. Remove carb jets and emulsion tube and clean all tiny orifices carefully. Rinse with Brake cleaner. Use eye protection.

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So here is what I have done so far, I installed a new (second one) fuel pump, this time a Mikuni and took off the chinese knock off as I read sometimes these are just not reliable, new Kawasaki fuel filter, pulled the fuel line out of the tank and it was clean, new air filter, checked for grass under the engine shroud. I started it up and I had a much stronger flow of gas out of the hose at the carb. I figured I got it fixed, WRONG, about 3/4 my lawn done and it sputtered out and quit running. I let it sit about 15 minutes, it started and ran good again to finish my lawn. I am going to put new plugs in it this week and if that don't fix it, maybe one or both coils may get weak when they get hot? Its really got me scratching my head! About 250 hours on it and it ran like a beast and now letting me down...

It sounds like you possibly have a blob of foreign contamination floating around in the tank and it is blocking the fuel pick up line at random. Old fuel cans are the worst for contamination buildup and possibly bugs getting in them.

Also, from what I can tell in a part diagram on Parts tree there is a vent check valve in the top of the tank for vapor emissions control. The valve may have failed and is creating a fuel cavitation (vacuum) in the tank. Try running until it acts up and then loosen the fuel cap and see if you can hear air sucking in as you loosen the cap.

Another possibility is if this has a special shaped pickup tube that is shaped to fit into the tank contour a certain way, it may be out of position and not picking up fuel when the fuel gets lower.

A couple of weeks ago, I had a John Deere 757 with a special shaped fuel tank tube that fit through the tank line grommet. It had to be "clocked" in the correct direction to work properly.