Hot start

[Derek gainard]

Have 2005 1.6 focus gia, will Drive all day no problem, turn off engine and when return no way will it start , leave for about 40 mins. starts and runs perfect , same every time , have changed sensors plugs air filter , had it in garage for 3 weeks ,mechanic could find nothing wrong , engine management system perfect , so am now at a loss ,any help would be greatly appreciated,