20
of the tank. A replaceable, high pressure, inline
fuel filter is built into regulator and another is in
line between the regulator and fuel rail. Mainten-
ance of the filters is critical to proper operation of
the fuel system and should be replaced according
to the maintenance schedule or more frequently
under severe operating conditions.
REGULATOR
The Regulator is a combination vaporizer and pres-
sure regulating device with a built-in LPG shut-off
solenoid valve. The fuel shutoff is a normally
closed valve on the vaporizer, controlled by the
ECM. The valve is opened is opened momentarily
when the ignition is first turned on to allow the sys-
tem to pressurize and when the engine is running.
When open, LPG passes into the regulator and any
liquid LPG is vaporized by heat provided by the en-
gine coolant. The fuel vapor pressure is then
reduced to approximately 88 kPa (12.6 psi) and
delivered to the fuel rail and fuel injectors. The out-
let fuel pressure is referenced to the manifold
pressure for a more stable idle.
Regulator
The regulator and some of components are servi-
ceable.
THROTTLE CONTROL DEVICE—DRIVE BY
WIRE
S
peed control is maintained by the amount of pres-
sure applied to the foot pedal located in the engine
compartment, however, in this Drive By Wire
(DBW) application, the foot pedal has an electronic
connection with the throttle and there is no direct
mechanical (cable) connection between the pedal
and the throttle shaft.
The ECM monitors the foot pedal position sensor
when the engine is running. When the operator
depresses or releases the foot pedal, the ECM
sends an electrical signal to the motor on the
electronic throttle to increase or decrease the an-
gle of the throttle blade thereby increasing or
decreasing the volume of air delivered to the en-
gine. Two internal Throttle Position Sensors
(TPSs) provide feedback to the ECM indicating
the position of the throttle shaft and blade. De-
faults programmed into the ECM software ensure
correct speed, load and emission control for all
throttle ranges.
A throttle related failure will cause a “LIMP
HOME” mode of operation, where the engine has
no response to the pedal.
THREE WAY CATALYTIC CONVERTER
The Catalytic Converter is a component of the
emissions system which is designed and cali-
brated to meet the emission standards in effect
for 2011 model year.
The exhaust gases pass through the honeycomb
catalyst which is coated with a mixture of metals
(such as platinum, palladium, and rhodium) to
oxidize and reduce CO, HC and NOx emission
gases.
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