Toro Pro Force 44552, Service Manual

Page: 41 / 134

Kohler Gasoline Engine
g278566
Figure 7
1. Pulse style fuel pump 4. Fuel shut-off solenoid
2. Governor control unit (GCU) 5. Oil pressure switch
3. Voltage regulator/rectifier 6. Digital linear actuator (DLA)
The engine includes an electronic speed control system. In addition to the
necessary linkages, the speed control system includes a Governor Control Unit
(GCU) and a Digital Linear Actuator (DLA). Electrical power must be available
to the GCU for the engine to start and run. Engine speed is adjusted by using
either the wireless or tethered remote. Refer to the KOHLER Command Pro
CH740 Service Manual for additional information.
The engine includes an oil pressure switch. When oil pressure is being generated
(engine is running) the switch is closed. On tethered remote machines, the
closed switch provides a path to ground for the hour meter circuit. On wireless
remote machines, the closed switch provides a path to ground for the hour meter
circuit and is an input for the Toro Electronic Controller (TEC). The TEC begins
to monitor the condition of the oil pressure switch 3 minutes after the engine is
started. When the oil pressure drops too low (switch circuit opens), the engine is
allowed to run for approximately 10 seconds and is then shut down.
The engine includes a pulse style fuel pump and a fuel shut-off solenoid.
Oscillating crankcase pressure causes a diaphragm inside the pulse style fuel
pump to pull fuel in on the piston down-stroke and to push it into carburetor
on the piston up-stroke. Two check valves prevent fuel from going backward
through pump. The fuel shut-off solenoid has a spring loaded pin that retracts
when 12 volts is applied, allowing fuel flow to the carburetor main jet. When
current is removed, the pin extends blocking the fuel flow.
Pro Force® Debris Blower Page 4–3 Engine: General Information
18237SL Rev A