On a couple of Volvo engines in our last boat, the hand primer pumps were a little anemic. But the Bosch hand pumps seems strong and bomb proof. The pumps are just the screw-in silver body below, about 1 1/2" in diameter.
Unscrew the top plunger- push plunger down-spring returns-repeat, and it will quickly pull fuel up from my tanks in the bilge to fill both dry filter housings(I never top them off after changing the elements). Screw the plunger top back down, no leaks.
Even running out of fuel when the IP needs bleeding, no problem.
These are pretty old style on many Japanese diesels and easy to find and replace, but I've never had one fail.