I am assuming this engine has sat for a while since running.
Try injecting some straight methanol into the pump line. Just in case the pump is gummed up from congealed oil.
Doesn't matter on the methanol even denatured alchohol will work.
Not sure what type of plug you have. Either a OS F type/YS 4-stroke plug work equally well. I have not had any luck with the A5 that comes standard with it.
Do not take the pump off the backplate. Bad @%$# happens as that opens up the pump just leave it on the backplate.