hi i have a 01 Fiat Seicento the head gasket was replaced yesterday wen we put it back together and started it up it only ran for a second then cut out so i checked the spark and there was none but if i leave it for a bit it will start for a second then cut out again and loss its spark its like the immobiliser is not going off but the pic of the key on dash goes out the pump is working ive tryed resetting the fuel cut off switch but it dont make any differance can anybody shed some light on this problem thanks