Accelerator Pump System - BRP Johnson J30TEL4SUA 2007 Service Manual

Accelerator Pump System

The 30 HP models are equipped with an accelera-
tor pump system. This system consists of an
accelerator pump on each carburetor with brass
tubes connecting the pump to the fuel output noz-
zles on each carburetor.
A normal engine characteristic during hard accel-
eration 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 charac-
teristic.
The accelerator pump system's function is to pro-
vide a balanced fuel/air ratio during acceleration
only by adding a specific volume of fuel to
enrichen the mixture. When the throttle is opened,
the accelerator pump lever pushes down on the
pump rod and plunger. As the plunger pushes
against the fuel, the check ball in the inlet passage
closes. Fuel is pushed out of the pump body
through the brass tube and outlet nozzle, spraying
into carburetor bore.
1
4
4
1. Pump lever
2. Pump rod
3. Plunger
4. Outlet nozzle
FUEL SYSTEM
OPERATION
2
3
6
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