[retodd7711]

Finally got around to swapping my oil pressure sending unit to mechanical instead of idiot lights. I ran a line from the block to the gauge but I'm not getting a reading. I can see the oil in the tube but no swing to the needle.
When i shut the truck off the line is oil,air,oil. But when I rev it up the oil goes all the way to the gauge. What's the problem? Picture is with motor off.