Lpg / Natural Gas Fuel System Diagnosis; Dual Stage Regulator - Kubota WG1605-E3 Diagnostic Manual

WG1605-G-E3,WG1605-L-E3,WG1605-GL-E3, DM
LPG / Natural Gas Fuel System Diagnosis (Open &
Closed Loop Systems)
DUAL STAGE REGULATOR (DSR)
This section of the manual has been prepared to
allow the technician to check the mechanical functions,
of the regulator and fuel delivery devices, of the
EControls "closed loop" fuel control delivery system. The
design of the EControls closed loop system is such that,
Diagnostic Trouble Codes (DTC) are employed to
monitor the fuel delivery system. To properly diagnose
fuel delivery system faults, you should first install the
EControls GCP diagnostic laptop tool to check for any
DTC present in the ECM first, and refer to the proper
DTC chart, prior to utilizing this diagnostic section.
The DSR is a combination vaporizer, pressure
regulating device. The DSR is a two stage regulator that
is a positive pressure regulator that is normally open in
the secondary chamber, when the engine is not running.
When the engine is cranking or running, pressure from
the secondary chamber passes from the regulator to
Direct Electronic Pressure Regulators (DEPR), and
mixer.
LPG / natural gas fuel enters the primary port of the
DSR, and passes through the primary jet, and into the
primary/exchanger chamber. As the LPG / natural gas
passes through the heat exchanger, the fuel expands
and creates pressure inside the chamber. The pressure
rises as the fuel expands. When the pressure rises
above 10 kPa (0.11 kgf/cm
is exerted on the primary diaphragm, to cause the
diaphragm plate, to pivot and press against the primary
valve pin, thus closing off the flow of fuel. This action
causes the flow of fuel into the regulator, to be regulated.
The secondary diaphragm is spring loaded on top of the
secondary diaphragm, causing the secondary lever to be
pressed down, which opens the secondary seat. When
the pressure in the primary chamber enters the
secondary chamber, the diaphragm is forced in an
upward motion, thus closing the secondary lever against
2
, 1.5 psi), sufficient pressure
the valve seat. When commanded by the ECM, the
DEPR will open, which causes a pressure drop in the
secondary seat, and allows the secondary seat to open,
and allow fuel to flow to the DEPR. The DEPR regulates
the fuel delivery to the mixer, based on the calibration
required, for the specific engine load and speed,
determined during engine fuel system development.
The DSR requires a connection to the engine
coolant, to prevent freezing in the regulator, during the
pressure reduction phase, within the regulator. Coolant
connections on the DSR are fitted with "Push In" fittings.
These fitting are designed with an o-ring seal, which
allows the fitting to be pushed into the water connection
on the DSR, and are then locked by spring locks, and
retained by screws.
The DSR is connected to the DEPR, by a low
pressure flexible hose. Like the other fuel hoses used in
the fuel system, the low pressure hose is designed with
a special inner core and may also be wire reinforced, to
prevent collapse of the hose, during high demand fueling
operations. The low pressure hose should only be
replaced with the
replacement.
The packaging of the regulator, into the engine and
chassis, has been approved by EControls, to insure
continued long term operation, of the fuel delivery and
emissions control system.
NOTE
• You should never relocate the regulator or any of
the fuel system components, as doing so may
cause excess build up of oil in the regulator,
improper coolant flow, or improper fuel delivery.
In certain regions, fuel supplies may contain different
chemicals and may employ different manufacturing
processes to make the LPG / natural gas, which during
the heating of the fuel in the heat exchange section of the
regulator, may cause "heavy ends", to accumulate over
time. The DSR is attached with a drain plug, to allow the
technician to drain excess oil and other contaminants
from the regulator. To determine the frequency for
draining the regulators, refer to the Recommended
Maintenance Schedule.
The regulator utilized on USA emissions certified
engines, are a critical part of the certified emissions
system, and do not require any periodic adjustment.
1-97
ECM SYSTEM
recommended Kubota
(To be continued)
KiSC issued 12, 2016 A
hose