Flaperon777,
I assume these are the same as the centre tank fuel boost pumps.
Yes, basically they are centre tank boost pumps but they have a dual function and therefore are officially named Override / Jettison pumps because they:
a. deliver a higher boost pressure than the main tank boost pumps to ensure the centre tank empties before the main tanks (they override the main tank boost pumps which normally also operate while fuel is fed to the engines from the centre tank).
b. they also function as jettison pumps in case a situation develops whereby fuel needs to be dumped.
Green-dot