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Service Manual – SC8000
Engine System, LPG
Functional Description
The LPG SC8000 machines use a four-cylinder 1.6L Kubota WG1605-L-E3 engine that is liquid cooled
and and naturally aspirated to power the two hydraulic pumps that run the machine drive wheel, scrub/
sweep systems, vacuum fan motor, the scrub/sweep and squeegee lift actuators and the steering system.
An E-controls Engine Management System modifies the fuel mixture based on feedback input from oxygen
sensors, and also controls the electonic throttle and ignition system.
Overview
The LPG SC8000 machines use a four-cylinder 1.6L WG 1605 Kubota engine to drive two hydraulic pumps.
Note:
Also refer to the following manufacturer’s technical literature for the WG 1605 Kubota Engine:
• Engine Operator’s Manual WG1605 EG523-89162ENG.pdf
•
Engine Specifications WG1605 9Y110-01770.pdf
•
Engine Workshop Manual WG1605 9Y111-06610.pdf
•
Diagnosis Manual ECM System WG1605 9Y110-01760.pdf
Kubota 1.6L LPG Fuel System Description
The fuel system on LPG engines includes an LPG Fuel Lock-off device, Dual Stage Regulator (DSR), Direct
Electronic Pressure Regulator (DEPR), Mixer Assembly and Electronic Throttle Body (ETB).
An LPG Fuel Lock-off device, consisting of a 12 volt solenoid and a normally-closed valve, opens during
cranking and engine run cycles. The ECM controls the voltage to the LPG Fuel Lock-off device.
The DSR is a two-stage regulator that is a combination vaporizer, pressure regulating device. The DSR is
normally closed when the engine is not running. When the engine is cranking or running, a partial vacuum
is created in the fuel line which connects the regulator to the DEPR and Mixer Assembly. This partial
vacuum opens the second stage regulator, permitting fuel to flow to the DEPR and Mixer Assembly.
The DEPR controls the fuel flow, and provides the correct air/fuel mixture to maintain performance and
emissions control. The DEPR uses an internal computer, and fuel pressure and temperature sensors to
provide input to the ECM for fuel calculation, fault detection and diagnostics.
The Mixer Assembly is a self-contained air/fuel metering device that utilizes a relatively constant pressure
drop to draw fuel into the mixer from cranking to full load. The Mixer Assembly is mounted in the air
stream, ahead of the ETB.
The ETB uses an electric motor, connected to the throttle shaft, to increase or decrease the angle of the
throttle blade. The ECM sends electrical signals to the motor in the ETB to increase or decrease the airflow
to the engine to control the engine speed.
Note:
For a more detailed and thorough description of the LPG fuel systems, refer to the
Diagnosis
Manual ECM System WG1605 9Y110-01760.pdf
.
