2001-2014 Honda BF/BFP8D, BF/BFP9.9D Outboards Shop Manual, Page 291Get this manual
BFBO-BF9.9D Automatic SE System
The SE (Starting Enrichment) thermal valve is the automatic SE system consisting of the PTC (heating element), thermo wax (thermal expansion element), piston, starter valve, etcWhen the engine is at stop, the starter valve is pushed up by the spring, making the fuel injection circuit open, and the SE thermal valve is ready to increase the fuel amount When the engine starts, the fuel is supplied through the fuel increase circuit, while the electric current from the heater coil flows to the PTC to heat itThe thermo wax is expanded by this heat, and this movement of the thermo wax pushes down the SE valve closing the fuel increase circuit as resultWhen the engine stops, the wax cools down and the fuel increase circuit starts to close, as the electric current stops flowing to the PTC