Electric Lock Off; Epr Assembly; Low Pressure Regulator (Lpr) - JLG 400S Service And Maintenance Manual

SECTION 3 - CHASSIS & TURNTABLE

Electric Lock Off

The Electric Lock Off device is an integrated assembly. When
energized the solenoid opens the valve and allows the Pro-
pane fuel to flow through the device. The valve opens during
cranking and run cycles of the engine. The lock off supply volt-
age is controlled by the engine control module (ECM).
Figure 3-104. Electric Fuel Lock Off

EPR Assembly

The EPR assembly is a combination Low Pressure Regulator
and a Voice Coil Assembly. The Voice coil is an electronic actu-
ator which is controlled by an internal microprocessor. The
microprocessor provides output data to the ECM and receives
input data over a CAN BUS connection. The internal micropro-
cessor receives electrical signals from the Fuel Pressure Sensor
FPS and the Fuel Temperature Pressure FTP and communi-
cates the data to the ECM. The ECM uses the FPS and FTP data
to calculate the location of the secondary lever in the LPR and
sends that data back to the EPR via the CAN BUS. The internal
microprocessor in the EPR will then output a signal, which
causes the voice coil to move and position the secondary lever
to the correct location.
1. Pressure Regulator Section
2. Fuel Inlet
3. Coolant Passage
Figure 3-105. EPR Assembly
3-134
4. Primary Test Port
5. Secondary Test Port
6. Voice Coil Section

Low Pressure Regulator (LPR)

The LPR is a combination vaporizer, pressure regulating
device. The LPR is a negative pressure, two stage regulator that
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 mixer. This
partial vacuum opens the regulator permitting fuel to flow to
the mixer.
Propane fuel enters the primary port of the LPR and passes
through the primary jet and into the primary/ exchanger
chamber. As the propane 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 1.5 psi (10.34 kpa), sufficient pressure 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.
When the engine is cranking, sufficient vacuum will be intro-
duced into the secondary chamber from the mixer drawing
the secondary diaphragm down onto the spring loaded lever
and opening the secondary valve allowing vaporized fuel to
pass to the mixer. This mechanical action in conjunction with
the EPR reactions causes the downward action on the second-
ary lever causing it to open wider allowing more fuel to flow to
the mixer.
THE VOICE COIL SECTION OF THE EPR ASSEMBLY IS AN EMISSIONS CONTROL
DEVICE AND CANNOT BE REBUILT. IF THE COIL ASSEMBLY FAILS TO OPERATE
PROPERLY, REPLACE IT WITH AN OEM REPLACEMENT PART ONLY.
Figure 3-106. Low Pressure Regulators
3121671