Clear Fuel Filter Almost Empty
I just finished addressing a fuel starvation problem which turned out to be sender unit gasket sealer dripping down into the gas tank and ending up in the clear filter between a pressure gauge and QJet inlet. I rinsed the tank out with water, dried it, blew down the steel fuel line from mechanical pump suction back to tank, then reinstalled sender with new rubber gasket and reinstalled tank. Left mechanical fuel pump untouched. And replaced fuel filter with clean one.
First two times out the car has run fine but when I shut it down and check under the hood, the clear filter is almost empty and the pressure gauge (just two inches upstream of the filter) shows about 4 psi. Gradually the pressure bleeds off over a couple of hours but the filter does not fill.
Starting the car and idling or short pulses of throttle show fuel slowly trickling into filter and pressure at steady 5-5.5 psi.
I don't understand why the filter doesn't fill solid. And how can there be 4 psi of pressure on the gauge and very little fuel in the filter? I disassembled the filter once to check for clogged inlet but it was clean. And there was nothing in the 3/8 inch rubber hose connecting the gauge to filter inlet.
Shouldn't the clear filter fill almost solid with fuel? Any theories? Can it just be air pressurized in the line?
Fuel pump is new with 6K miles on it.