yam ybr 125 fuel pump not priming

[jay9119]

hi every one i set about a challenge of changing of building a dirtbike with a fuel injected engine, i opted for a ybf motor from a cat c wright off, bike ran sweet, i swapped over the engine's reinforced the frame and swapped over the wiring, i also fitted a inline fuel pump/filter and fpr, not has come to test fire and my pump wont prime if i add a live it works but off the ybr loom its just not working i have spark and have repeatedly checked earth, i have reconnected the old pump to see if the was a conflict but that never worked. i have come so far but still miles away. any advice please