Lawn tractor keeps stopping.

I have a John Deere Model 185 lawn tractor. Last week it stopped on me while I was mowing my yard. I had mowed for about 45 minutes. Last year it did the same thing. I changed the fuel filter and it had run fine since. I thought that it was the fuel filter again so I replaced it again. After mowing for another half hour it did the same thing. The mower starts to sputter and it sounds like it's under load and then it dies. I can let it sit for about a half an hour and it starts right up.
I changed the spark plug and the air filter and also cleaned the fins on the motor (this is air cooled) and it did it again today. Nothing I've done seems to help. Any ideas? Need to get this fixed because my grass continues to grow!
Thanks for any help or advice.

Mike: confused:

 

Try posting your question in the Outdoor Power Equipment and Small Engines section of the forum. They do nothing but talk small engines and should be able to help you.

Have you tried loosening or removing the gas cap?

 

So what about the safety cutoff switch under the seat? Even if one of the springs under the seat are broken then the switch can start acting up even if the switch itself isn't defective. Just a thought. But usually in that case you'll just get random backfiring.

 

I have copied this post over to the "Outdoor Power Equipment & Small Engines" section. I didn't find that section before. Thanks! I'll try your tip about loosening the gas cap.
Thanks again.

 

Removing the gas cap? You aren't serious are you? Terrible advice.

 

Yes, I am serious. If the gas cap is not venting properly air cannot enter the tank as fuel is consumed by the engine. This slowly develops a vacuum in the tank and eventually the engine cannot draw fuel against the vacuum so the engine sputters and dies as it starves for fuel.

Mow your lawn as usual and when the engine starts to sputter loosen/remove the gas cap so air can enter the fuel tank. If the engine runs properly you have identified the gas cap as the culprit.

 

I doubt Pilot Dane was suggesting operating the lawn tractor without the cap, just removing it to see if there is any built up pressure. My farm tractor would build up pressure in the tank and not run quite right, removing the cap long enough to vent the pressure would fix it. I've since replaced the cap


I guess I type too slow

 

I'll try it by loosening the cap a bit to see if that works before I mow. It starts acting up and stopping so quickly that I'll never be able to do it while I'm mowing.
Thanks,
Mike

 

If it just dies without much warning after the engine has gotten good and hot I would look at the coil. They can go bad and stop working when they get hot but will work again when cooled down.

 

I tried mowing with the cap loosened and it stopped again after about 30 minutes.

Mike

 

Is the fan or head fins clogged with grass and dirt? It could be overheating and getting vapor lock.

Also, the float valve could be sticking.

 

I had a (irregularly) bad coil on a JD 277 and it drove me nuts. It would run (barely) when it kicked off and run fine when it worked.

 

I was able to finish my mowing yesterday, although the mower stopped on me once. I am going to pick up a spark tester so the next time it dies, I'll be able to check for spark.
Thanks,
Mike