Agilent 1100 Quat pump working and not leaking but not flowing

Hey David, I recommend using isopropanol to try and reprime the system. The viscous solvent is good for getting rid of air bubbles in the system which could cause the "airlock". Open the purge valve and set the flow to 3-5 ml/min and see if you are getting the isopropanol to flow out of the purge valve waste. If it does not make it to the purge valve, you can release connections one by one to support getting rid of the airlock. I normally start with the connections from the degasser to the pump and work my way forward to see at what location the flow is no longer present. Hope this helps.

Do you have a degasser? I would try bypassing the degasser and then disconnecting at every connection to understand up to what point it reaches. Another option is if you have a  syringe and an adapter, you could suck the air out of the solvent lines. You wanna use IPA for that, it is great to remove air

First loose the AIV assembly on the pump head and allow to bleed little solvent through AIV cartridge. Then tight the AIV assembly on the pump head. Most of the time, pumping issue will be solved. else needs to change the AIV cartridge 

When the air is sucked out, sometimes it is difficult because it faces resistance. Shall the flow be on while doing this maneuver?  

Yes