C-15 BXS series losing prime

It is located in the secondary filter housing closest to cab facing down. I beleave it is a one inch size wrench you need to take it out. It looks like a plain old pipe plug like you would fine in a valve plugging up a none used port. Once you take it out it is all one peice and it will come out in your hand. I would change that first, I beleave thats your problem, If not there is a regulator in your fuel pump that goes bad and causes the same problem. There is a updated spring kit that they sell for your fuel pump that helps raise fuel pressure. If I where you I would just change them both and just get it over your truck will run better with that updated spring kit and a new check valve you will be suprized. If that check valve/regulator in fuel filter housing is letting fuel drain back to tank it's definatly not keeping your fuel pressure up to spec. These are the first things that I would do and you should be back to normal.