Your pump is probably on itś way out.. They don last long..Try a new 1100 and see the difference. They are cheap. Iḿ going to pull mine out, and try an external Jabsco like some of the other guys are doing.
right now with a new 1100, it flows good, but notice it falls off over time.
right now with a new 1100, it flows good, but notice it falls off over time.