do i need inline electric fuel pump w/ mech pump ??

[5.8_97_ranger]

i just put on a new mechanical fuel pump on today and its not pumping any fuel to the carb? motor is 351w. i dropped the tank and removed the factory intank pump and replaced it with a rubber hose to the depth of the intank pump. and ran a rubber 5/16 rubber fuel line to pump then to carb. the tank is full with gas. a mech. pump should pull it from the factory tank right?? or do i need to install a low pressure inline pump? cant figure out why its not pumping

thanks for any help.