Yes, this is definately possible with diesels since they have a "sealed" fuel system. If there is a leak anywhere in the system.....and by leak I don't mean an actual drip......this will allow air to enter the fuel system and then the fuel will by syphoned all the way back to the fuel tank. It's like sucking a drink up into a straw and putting your tongue over the end of the straw. The liquid will remain in the straw. But if you poke a hole in the straw, the straw has slight cracking, etc. there goes your liquid. Same deal on your dielsel and that's why there are clear plastic fuel lines from the filter to the injection pump. So you can see if you have fuel at the read, or air in the line, etc.

Remember that diesel is compression ignition. This is especially important cold! If your engine has compression that's on the low end of spec, or you have the wrong weight of oil for your cold starting conditions, or a slow cranking starter due to marginal battery, or battery cables that are just too small in diameter or poorly installed, you'll have hard cold starting.

Typically if a diesel is syphoning it's fuel, it will not start at all, no matter what. That's why you have that priming pump on the side of the injection pump...so you can prime your own system should it ever syphon back, either due to a leak or due to being taking apart for repair work of some sort.

If yours starts on it's own, you probably don't have syphoning. You probably have either low compression or slow cold cranking speed as I mentioned above.

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