I suppose each model coach is plumbed differently, but for mine, the city water connection is right after the water pump. So if you are getting sufficient water pressure with the pump, the most likely culprit - if it is a problem with your RV and not city water - is the water inlet and a few feet of hose.
The water inlet should have a valve built into it, so that would be the first place to check. As indicated above, check the screen, but also check the valve itself.
The only thing that works on a RV is the owner...