They are Bit%ch to prime. Had to go through that once. I filled the line with fuel and cranked and cranked till she fired. The hand pump is useless even after I rebuilt it with new o-rings.
Don't know if it is supposed to push or pull but I never got a drop out of it. There is a question in my mind if the bleeder needs to be open or closed while pumping.
many threads on priming in the 5 ton forum. Some problems noted with fuel pick ups in the tank, canister not sealed tight, cracked and aged rubber fuel lines, and plastic vents etc........