I was changing some things out on the injector side of a 6890B. The rear injector is maintaining pressure without a column inserted into the injection port. Is this normal? However, the front injector is not. When I cap off the front injection port it does. The pressure on the front rises to the set point and maintains. I checked the nut at the top of the front port (that conceals the septum) and that seems fine. I thought something might have been loose as I also changed the liners and septa. In the past, when that nut is too loose I have a hard time getting the injector to pressure.
Even when I put the column into the front port it does not maintain pressure. When I replace the column with one of those screw-in caps and it does.
Any idea what gives?