There I was mowing away on my 1991 JD 260... It's hot and humid and we are workin' it in the 6 in grass... when it just stops running I cleared the blades of the excess grass. I tied to restart it in N, PTO off. It turns and turns...nothing. I tow it to the barn... It's got fuel..i pulled a fuel line and cranked it filter is clean and 1/2 full. I pulled plug... it appears to have spark. Air filter looks ok. I dont get it... Spark, fuel and air...It should start or pop or blow up...but nothing. Whats gives??..... Vapor lock?