I've used the squirt of petrol direct into carb on vehicles that have sat around. It works but you can flood it very easily. I'd rather use that method than happy gas on a petrol engine. The other real fun way with a Disiel is of course the flaming rag over the air intake, who really needs eyebrows anyway? Years ago I had charge of a Series 1 Landy. No matter what was done if you left it overnight, you had to start on the handle. Half Choke throw the engine over away it went, then would start on the switch until left for about twelve hours. Numerous gagrages tried to cure it, none succeded. I think now the engine may have pinched a bit when cold. But hey, we had a system that worked. If you can turn the engine without the ignition, do that a couple of times, to bring fuel up then switch on. All the old tricks time has forgotten.