Concern about accidental siphoning

Greetings all.
I have a MEP-804B, and I’m going to hook up the aux fuel line to a 55gal drum. With a full drum sitting next to the gennie the fuel level of the drum will be higher than the internal fuel tank. I,m worried about fuel accidentally siphoning out of the drum when the aux pump is not running. Can fuel continue to flow (trickle?) through the aux pump and overflow the internal tank if nothing is running?
Thank you very much for your time,
Sincerely
Sean