I have had this one my self, you will find its one of the injectors ( could be more than one) leaking off a vast amount compared to the others, simply remove the leak off pipe clips and remove the leak off pipes dry all the area around the injctors and crank the engine over for a short time, one of the injectors will be leaking more than the others not allowing the high pressurers that are required to start  the vehicle as the pump is only rotating at half cranking speed. the injectors are class there a number on them either 1, 2 or 3 make sure you replace with the same injector class, you should alos replace the high pressure pipes once removed and make sure the injector copper ring is intact and clean.

Hope this is of some help John