Willy's Load Related Fuel Pressure Regulator automatically adjusts fuel pressure according to manifold vacuum. At idle or deceleration, when manifold vacuum is high, regulator opens and drops fuel pressure for clean restarts and keeps carburetor from flooding or blubbering in corner. As throttle is opened, manifold vacuum drops which closes regulator and raises pressure for proper straight away fuel mixture. It is a fully CNC machined piece. Easy installation - requires fuel return line and vacuum port (base plate or intake manifold).Pit Stop USA offers Willy's Fuel Pressure Regulator 890 at low everyday prices. Be sure to check out all of our products from Willy's Carburetors including Willy's Carburetors Fuel Pressure Regulators.