2001-2014 Honda BF/BFP8D, BF/BFP9.9D Outboards Shop Manual, Page 289Get this manual
SFBO-SFS.SD 1ACCELERATOR PUMP
17OPERATION
2Starting Enrichment (SE) SYSTEM
1ACCELERATOR PUMP
The acceleration pump is equipped to prevent the lean airfuel mixtureIn short, it is designed to increase the fuel amount and make the airfuel mixture richer when the throttle opens quicklyWhen the throttle valve opens, the acceleration pump piston is pushed down via the pump robBecause the inlet check valve is closed this time, the pump chamber is pressured and the outlet check valve is opened Therefore, the fuel is injected from the nozzle into the main bore When the throttle valve is closed, the acceleration pump piston is pushed back by the spring force, the inlet check valve opens, and the fuel in the float chamber enters the pump chamberThe outlet check valve is closed this time, preventing suction of the air through the nozzle