Ben - soapy water and a soft brush.

Boswoj -"Same reason that fuel pressure regulators work - if all other factors are equal, higher pressure means higher velocity and higher GPM."

The purpose of a regulator is to maintain a desired pressure. It can only do this within the rated flow capability of the specific regulator. Controlling downstream pressure they’re called regulators, controlling upstream pressure they’re called back pressure regulators or relief regulators. The regulators’ only purpose is to maintain the set point pressure. As the flow increases the set point delivered usually drops off (droop). Once the flow reaches the capacity of the regulator the pressure will drop off significantly depending on the downstream demand. Piloted regulators, ( a regulator that controls a regulator), will have better (less) droop characteristics but will be slightly slower than a direct operated regulator at responding to changes in downstream pressure caused by changes in demand for flow. The purpose of controlling the pressure delivered is to get a controlled flow through a given system without fluctuations due to changes upstream. On a fuel system the pump delivers an output that would change pressure significantly with changes in demand for fuel. The regulator supplies a constant pressure so that the rate of flow into say the float bowls of a carburetor is fairly constant and sufficient for demand yet not too much pressure that the float valve can’t shut it off. Want to know more about regulators? Go to www.fisherregulators.com Enjoy!