UK Car Repair: rover metro 1.2 injection 1995, rover metro, first time every time

Question
hi i have a metro which starts up first time every time, the car will run fine for between 10 minutes to a day or two.then without warning the engine will just cut out,it will turn over straight away but will not fire up.if i leave the car for 20 minutes or so it starts up straight away. hope you can help as the car is not being used as it can stop at anytime

Answer
My first check would be the crank and cam sensors, remove them for cleaning and to see if they are still magnetic.  Otherwise, when the fault occurs you have to physically check for a spark at the plugs, if OK then you have to remove a spark plug and see if it smells of petrol.  Let me know the result.