JLG 660SJ Service Manual - Manual (Page 120)

SECTION 3 - CHASSIS & TURNTABLE
3-70 – JLG Lift – 3121202
3.15 FORD LPG 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 powered engines.
Description
The LPG system starts at the tank. The liquid propane
exits the tank, flows through the fuel lockoff solenoid,
flows through the regulator (regulator converts the liquid
to a vapor), flows through the megajector, flows through
the mixer and into the engine.
Regulator
The regulator accepts LPG liquid at tank pressure (min =
30 psi; max = 312 psi [min = 207 kPa; max = 2151 kPa])
and reduces it to a regulator outlet pressure of 1.5 to 2.5
inches (3.8 to 6.3 cm) of H
2
O at idle flow (approx. 750
RPM / no load). This regulator must have engine coolant
flowing through it whenever the engine is running.
Megajector
The megajector is an electronic pressure regulator. This
electronic regulator outputs a specific pressure needed at
the mixer to maintain the desired air to fuel ratio. The
megajector accepts LPG vapor at the regulator outlet
pressure (1.5 to 2.5 inches [3.8 to 6.3 cm] of H
2
O) and
reduces it to a pressure value commanded by the EPM.
The pressure command is sent by the EPM over the CAN
link via the megajector harness. The megajector outlet
pressure has units of inches of H
2
O. The megajector out-
let pressure is defined as the difference between the
megajector outlet gas pressure and the balance line pres-
sure (usually at or near barometric pressure depending on
air intake restriction). The megajector outlet pressure can
vary between -1.00 to -5.00 inches (-2.5 to -12.7 cm) of
H
2
O depending on the speed and load of the engine. The
megajector must be mounted per the 2.5L 2004 Emission
Installation Instructions. Torque mounting bolts to a maxi-
mum of 60 in.lbs. (7 Nm).
Mixer
The mixer accepts LPG vapor at the megajector outlet
pressure (-1.00 to -5.00 inches [-2.5 to -12.7 cm] of H
2
O)
and mixes it with clean air. This mixture is then sucked into
the engine via the actuator.
Lockoff Solenoid
The lockoff solenoid is used to reduce the possibility of
backfires. The EPM controls the opening and closing of
the lockoff so that as a shutdown is commanded, the lock-
off is closed, but the ignition system continues to operate
to burn off unburned fuel in the manifold. This will cause
longer than usual start times, because the manifold must
fill up with fuel again before the engine will fire. This will
also cause the engine to run for one to two seconds after
ignition is turned off.