The Series 5500/5600 CruiseMaster fits virtually all inboard, I/O, and outboard engines from 50 hp - 1000 hp including EFI, TBI, and DFI engines with closed loop return fuel systems and all carbureted engines. A system consists of Series 20B or 231 fuel flow sensor(s) and a microprocessor based instrument which displays individual flow rates and total fuel consumption. New Series 5800 CruiseMaster fits EFI engines with fuel return lines that are connected directly to the fuel tank. A system consists of two Series 231 flow sensors to measure feed and return flows and a microprocessor based instrument which calculates and displays net flow rate and total fuel consumption. FloScan CruiseMaster Fuel Meter