185Service Manual – CS7000
Engine System - LPG LEV
This chapter provides a brief summary of the Kubota propane “LEV” (Low Emission Vehicle) engine which
was introduced around September 2015. Kubota refers to the engine model as WG972-E4. “E4” designates
EPA Tier 3 / CARB Tier 4 models, depending on engine displacement and output classication. “E4” engines
are identied with “EF” at the end of the Model designation, on the US EPA label.
Since more than one WG972 propane engine is available, the easiest way to visually identify the “E4” model
is that it has COP (Coil On Plug) ignition.
See the Kubota “Workshop Manual – Gasoline, LPG, NG Engine WG972-E4 (EFI)” Code No.9Y111-11080 for
detailed information related to the complete mechanical engine. See the Kubota “Diagnostic Manual ECU
System WG972-E4” Code No.9Y110-03110 for detailed information on the engine management system.
Functional Description
The WG972-E4 engine is a three cylinder, liquid cooled, naturally aspirated engine. An Engine Control Unit
(ECU) is mounted to the side of the engine block. The ECU manages the engine speed, the ignition system
and the fuel system. The ECU and main machine controller convey several pieces of information through
dedicated wires such as requested engine speed and whether to display the MIL icon.
The fuel system begins with a propane fuel tank which is horizontally mounted on the right side of the
engine compartment. The tank swings out to provide easier access to the engine compartment. There is
an in-line pressure relief valve and a pressure switch between the tank and the fuel pressure vaporizer/
regulator.
The engine RPM is controlled by the ECU through a motorized throttle according to input requests from the
main machine controller.
The cooling system consists of a standard radiator and belt driven fan. Note that the fan pushes air away
from the engine and out through the radiator.
COP Ignition
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