G420E/G424E Tier LP Engine Maintenance Schedule 33
Testing Fuel Lock-off
Operation
z Start engine.
z Locate the electrical connector for the fuel lock
(A).
z Disconnect the electrical connector.
z The engine should run out of fuel and stop within
a short period of time.
z Turn the ignition key switch off and re-connect
the fuel lock-off connector.
(A) LP fuel lock-off (B) LP regulator/converter
(C) Fuel Trim Valve
NOTE
The length of time the engine runs on
trapped fuel vapor increases with any
increase in distance between the fuel
lock-off and the pressure
regulator/converter.
Pressure
Regulator/Converter Testing
and Inspection
z Visually inspect the pressure regulator/converter
(B) housing for coolant leaks. Refer to the
pressure regulator/converter section of the
service manual if maintenance is required.
NOTE
For pressure testing and internal
inspection of the pressure
regulator/converter, refer to the pressure
regulator/converter section of the service
manual.
Fuel Trim Valve Inspection
(FTV)
z Visually inspect the Fuel trim valve (C) for
abrasions or cracking. Replace as necessary.
z To ensure the valve is not leaking a blow-by test
can be performed.
1. With the engine off, disconnect the electrical
connector to the FTV.
2. Disconnect the vacuum line from the FTV to the
pressure regulator/converter, at the converter’s
tee connection.
3. Lightly blow through the vacuum line connected to
the FTV. Air should not pass through the FTV
when de-energized. If air leaks past the FTV when
de-energized replace the FTV.
Inspect Air/Fuel Valve Mixer
Assembly
Refer to the LP mixer (G) section of the service
manual for procedures.
(G) LP mixer
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