小中大All the tubing will create pressure. You can check block by block to find the source of pressure creation. Part of you capillary may be blocked to some degree. Check the pressure with or without connection to your detector, you can check out how much pressure you have in your flow cell. Your have 80 bar in your pressure display doesn't mean you have 80 bar in your detector. If you see some part of your capillary give you significant pressure increase, replace that capillary.
