Gm Engine Dual Fuel System; Fuel Filter - JLG 400S Service And Maintenance Manual

4. After running the engine for 5 minutes after it has
reached operating temperature, shut the engine off and
continue to step 5.
WITH THE ENGINE RUNNING OR WHEN SHUTTING OFF THE ENGINE, SOME
HEATED COOLANT MAY SPILL OUT DUE TO AIR "BURPING" OUT OF THE SYS-
TEM WITH THE RADIATOR CAP OFF.
5. Next, verify that the 2 coolant hoses on the EPR are
warm. If they are not warm repeat step 3 and 4, other-
wise continue to step 6.
A PROPERLY PURGED COOLING SYSTEM WILL YIELD A WARM UPPER RADIA-
TOR HOSE AND A WARM EPR HOSE. IF THE UPPER RADIATOR HOSE AND/OR
EPR HOSE ARE NOT WARM TO THE TOUCH AFTER THE ENGINE HAS RUN FOR 5-
8 MINUTES AFTER REACHING OPERATING TEMPERATURE, THE SYSTEM MAY
STILL CONTAIN AIR. IT MAY BE NECESSARY TO REPEAT THE ABOVE STEPS.
6. Fill radiator with coolant as needed and install the radia-
tor cap. Next, remove the cap off the coolant recovery
bottle and fill just below the HOT FULL line and reinstall
the caps.
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SECTION 3 - CHASSIS & TURNTABLE

3.24 GM ENGINE DUAL FUEL SYSTEM

NOTE: +20° F (-6.6° C) is the low temperature limit for LP gas, for
both starting and operation. This applies to all LP gas pow-
ered engines.
The Dual Fuel system allows the operator to operate the vehi-
cle on either gasoline or LPG by positioning a selector switch
in the operator's platform. When the operator places the selec-
tor switch in the gasoline mode the gasoline fuel pump is
energized. While in the gasoline mode the LPG fuel lock-off is
isolated and will not energize. In addition the gasoline injector
circuit is enabled and injector pulses are provided to each
injector and the ECM calibration for gasoline is also enabled.
When the operator selects the LPG mode the Low Pressure
LPG lock-off is energized and fuel from the LPG tank flows to
the Electronic Pressure Regulator (EPR). The EPR receives an
electronic signal to position the secondary lever for the start or
run positions and when the engine begins to crank the mixer
air valve will rise and fuel will begin flowing to engine. During
this mode the gasoline fuel pump is isolated and will not be
activated. The primary components of the gasoline dual fuel
system are the gasoline tank, electric fuel pump and filter, fuel
supply line, injector rail and injectors and the fuel pressure
regulator. The primary components of the LPG dual fuel sys-
tem are the LPG fuel tank, in-fuel filter, LPG Low Pressure lock-
off, Electronic Pressure Regulator (EPR) and the fuel mixer
module. The LPG fuel system operates at pressures which
range from 14.0 in. (355.60 mm) of water column up to 312 psi
(21.5 bar).
Components which are shared by both systems include the
Electronic Throttle Control and the ECM. The ECM contains a
dual calibration; one controls the gasoline fuel system during
gasoline operation and one controls the LPG fuel system dur-
ing LPG operation.

Fuel Filter

Propane fuel like all other motor fuels is subject to contamina-
tion from outside sources. Refueling of the equipment's tank
and removal of the tank from the equipment can inadver-
tently introduce dirt and other foreign matter into the fuel sys-
tem. It is therefore necessary to filter the fuel prior to entering
the fuel system components downstream of the tank. An
inline fuel filter has been installed in the fuel system to remove
the dirt and foreign matter from the fuel. The inline filter is
replaceable as a unit only. Maintenance of the filter is critical to
proper operation of the fuel system and should be replaced as
Section 1. In severe operating condition more frequent
replacement of the filter may be necessary.
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