Why does my Craftsman rider run perfectly for 15-20 minutes then die?

My 2 year old Craftsman rider starts right up and runs and cuts perfectly for around 15 minutes then slowly starts to lose power until engine dies and will not start back up. An hour or two later the engine will start back up and the same scenario happens

Update (06/21/2016)

The mower is a T100 Crafysman with a 420cc overhead valve engine. All gas lines are far enough away from heat sources that I don't believe vapor lock would be an issue. All maintenance has been kept up

Update (06/21/2016)

I meant a T1000

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Just an update on my Craftsman mower. Did a compression check and had very little compression. Haven't had a chance to dig into it to see if motor is shot. It is correct that the mower has a MTD engine. They stick Craftsman stickers all over it to make you think otherwise. Hoping it's a valve spring or a keeper or something fixable. Mower is just out of warranty (of course).


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@amycollin sounds like it is related to heat. Make sure that your cooling fins etc. are clear of any obstruction. Ensure that all fuel lines etc are away from the block and potentially causing a vapor lock. If you tell us what model your mower is and what engine it has we should find more concrete information for you.

Update (06/26/2016)

@amycollin if the unit is running with restricted fuel flow it can cause overheating. If the spark plug looks dry and white after some use instead of slightly wet or tan colored, then it still could be caused by something restricting the fuel supply. Check for a partly blocked fuel line, fuel filter, or tank vent,possibly even something inside the carburetor. Also, check if you still have spark when the unit is hot and stalls out. Sometimes an ignition coil or spark plug can work fine when cold but short after having enough time to heat up. Change the plug. Post an image of the spark plug face with your question use this guidefor that. You also can check the intake and exhaust valves for proper settings (trying to find more info for this particular engine) If they are running a little to tight they will close when the engine is hot and causing those symptoms.

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@amycollin that sounds like the model they are pushing as a craftsman engine. Where they used Kohler and B&S there are now more of the Zongshen gasoline 1-cylinder 2-valve 420 cc engine. Any issues related to the engine cannot be found in the mowers service manual, but it's in the engine manual. So we'll have to investigate yours carefully. If you are sure it's not vapor lock make sure that it is not creating a vacuum anywhere, ensure the tank is vented. This "starts to lose power until engine dies " is usually fuel related. I added more to my answer. Lets see if we can figure it out. Check on the engine for any identifying marks,numbers etc. Just learned that there are also models with a B&S engine and peerless engines.


Would a improperly capped spark plug cause this?


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