Low fuel pressure with new fuel pump

It won’t fit anywhere in the frame rail, and more on that is I couldnt get it below the tank. It’s mounted off the spare tire well from the trunk. It’s behind the tank, but equal to the bottom of the tank. I mean I understand it’s not good at pulling, but the way the sending unit is mounted in the tank, the gas line is pointing upwards. That’s the only pull it would have to do. I’ll try to post a picture of the pump for a better idea.