DSG-423 FUEL SYSTEM
04-23
Diagnostic Aids
Fuel Lock Solenoid
:The fuel lock is an electronic solenoid that is opened to allow fuel flow when the key is turned
ON. High temperatures may cause the solenoid to become intermittent, not opening to supply sufficient fuel
pressure.
Fuel Filter
:There is a filter element located in the inlet of the fuel lock which may become clogged and limit fuel flow,
especially at low tank pressures. Check the filter and replace as necessary.
Fuel Line Restrictions
:The vehicle specifications table specifies the fuel line to be a certain size. If the fuel line from
the tank to the fuel lock is not the proper size, or any valves or fittings with flow restrictive characteristics are used,
the fuel flow will not be sufficient to the converter with low tank pressure. Correct any fuel line or fitting restrictions.
Mixer Assembly (Carburetor):It is possible that a backfire may have caused the fuel valve to partially come off of it's
retainer and restrict fuel, check the mixer fuel valves, see section 475-1 for disassembly. Also check the mixer
adapter plates for leakage past the carburetor.
Regulator Assembly
: If no other problems have been identified, replace the fuel management assembly with a
known good part of the same pressure range. Retest..
4 Check carburetor air valve for binding. Yes
No
Refer to section 475-1 for servicing the
carburetor.
Go to ?????????.
• Key ON, Engine Running.
• With the air cleaner removed, pull the air valve piston
upwards to ensure free movement of the carburetor air
valve.
Is the air valve binding?
7 Check air valve operation. Yes
No
Refer to section 475-1 for servicing the
carburetor.
Refer to Diagnostic Aids Below.
• Using the WTK-1 test kit, connect the vacuum gauge
between the carburetor and the FCV valve to measure the
carburetor air valve vacuum (AVV).
• With the engine at idle and accelerating observe the
amount of measured vacuum.
Is the measured vacuum outside the specifications?
Engine Backfires (Continued)
Test Step Result Action to Take
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