I have had this before and it was a fuse to power the injectors.(they are earthed by the ECU).Fault for fuse blowing was a heating element in the engine breather.It was not much to look at,just a small plastic pipe joiner about an inch long with a small 2 pin plug on it. I cannot rememver the fuse location but it was not hidden.On the wiring diagam it said heated breather for cold climates.I just dis-connected it, replaced the fuse...."Down the road Motors!" I hope this helps.(as I hate typing)