5-20 FUEL SYSTEM
ACCELERATOR PUMP SYSTEM
The DF25/30 models are equipped with an accelerator pump system. This system is composed of an accelerator
pump on each carburetor with brass tubes connecting the pump to the fuel output nozzles on each carburetor.
A normal engine characteristic during hard acceleration is hesitation caused by an imbalance in the fuel/air
ratio. This is due to the rapid rate of increase in intake air volume when the throttle is opened quickly with the
air velocity and fuel flow rate following at a slower rate of increase. The accelerator pump system overcomes
this characteristic.
Accelerator pump operation
The accelerator pump system’s function is to provide a balanced fuel/air ratio during acceleration only by
adding a specific volume of fuel to richen the mixture. When the throttle is opened, the accelerator pump lever
1 pushes down on the pump rod 2 and plunger 3. As the plunger pushes against the fuel, the inlet passage
check ball closes and fuel is pushed out of the pump body, through the brass tube and outlet nozzle 4,
spraying into carburetor bore.
To Next Page
Need help?
General
