JLG 740A, Service And Maintenance Manual

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SECTION 3 - CHASSIS & TURNTABLE
3121160 – JLG Lift – 3-133
Fuel Filter
After the fuel is drawn into the fuel pump, the fuel flows
through the gasoline fuel filter. The fuel filter will trap small
particles as the fuel passes through the filter to remove
debris and prevents the fuel pressure and temperature
manifold and fuel injectors from becoming damaged.
Maintenance of the fuel filter is required as indicated in
Section 1.
Fuel Injector Rail
Fuel flows from the fuel pressure and temperature mani-
fold assembly to the fuel rails where the fuel is delivered to
the fuel injectors. The fuel rail also contains a Schrader
valve which is utilized to test the regulated pressure of the
fuel system.
Fuel Injector
The fuel supply is maintained on the top of the injector
from the injector rail. The injector is fed a "pulse" signal
through the wire harness which causes the injector to
open. During regular operating conditions the ECM con-
trols the opening and duration of opening of the injector.
During lower RPM operation the injector signals or
"pulses" are less frequent then when the engine is operat-
ing at higher RPMs. The engine has been calibrated to
deliver the precise amount of fuel for optimum perfor-
mance and emission control.
3.29 GM ENGINE FUEL SYSTEM REPAIR
Propane Fuel System Pressure Relief
THE PROPANE FUEL SYSTEM OPERATES AT PRESSURES UP TO
312 PSI (21.5 BAR). TO MINIMIZE THE RISK OF FIRE AND PER-
SONAL INJURY, RELIEVE THE PROPANE FUEL SYSTEM PRES-
SURE (WHERE APPLICABLE) BEFORE SERVICING THE PROPANE
FUEL SYSTEM COMPONENTS.
To relieve propane fuel system pressure:
1. Close the manual shut-off valve on the propane fuel
tank.
2. Start and run the vehicle until the engine stalls.
3. Turn the ignition switch OFF.
RESIDUAL VAPOR PRESSURE WILL BE PRESENT IN THE FUEL
SYSTEM. ENSURE THE WORK AREA IS WELL VENTILATED
BEFORE DISCONNECTING ANY FUEL LINE.
Propane Fuel System Leak Test
NEVER USE AN OPEN FLAME OF ANY TYPE TO CHECK FOR PRO-
PANE FUEL SYSTEM LEAKS.
Always inspect the propane fuel system for leaks after per-
forming service. Check for leaks at the fittings of the ser-
viced or replaced component. Use a commercially
available liquid leak detector or an electronic leak detec-
tor. When using both methods, use the electronic leak
detector first to avoid contamination by the liquid leak
detector.