[Hubscrub]

I replaced the driver side tank on my 85 K10 and installed a new sending unit since my old one wasn't reading anymore. So i can not get gas to the carb from that side passenger tank does fine. So i bypass the switch tank valve and plumb the new tank directly into the lines to the pump still no fuel. Took tank back out checked sending unit etc. blew air through lines all clear. Did notice that return port on sending unit seemed hard to blow through. Reinstalled still no fuel when i take the 3/8 line off they is pressure released from it. Could the sending unit be bad? Im at my whits end. Thanks