As a young (very young) kid I dumped a case of shotgun shell power in to a hole, covered it with the shot made a paper fuse as new was all set to “touch it off” when mom found out what I was about to do. Yep, it never happened.
I think it depends on how long the engine has been sitting. Keep in mind it’s a long was from the pick up to the pump. You’re going to have an air pocket to deal with.
To be safe I’m going to pressure prime my new 6.4. I just haven’t figured out the details.