GE fuel lines to each cylinder are made of heavily reinforced hoses, but by their very location, if they develop so much as a pinhole, the high fuel pressure causes it to spray all over inside the carbody, inevitably hitting something hot enough to ignite it. By the time it ignites, there has usually been enough fuel sprayed around in there already to start a good fire. Or a bad fire.

EMD fuel lines are inside the top decks. When they leak, fuel gets into the oil, diluting it. Eventually, the rod and main bearings suffer, or there can be a crankcase explosion, which is quite a thrill when it happens on the locomotive you happen to be riding.