DSG-423 FUEL SYSTEM
04-12
Diagnostic Charts
Perform the preliminary test before proceeding.
Engine Cranking But Will Not Start
Test Step Result Action to Take
1 Check fuel tank. Yes
No
Fill or replace the fuel tank.
(Do not exceed 80% of liquid capacity)
Go to Step 2.
Is fuel tank empty?
2 Check fuel valve. Yes
No
Slowly Open the Fuel Valve.
Go to Step 3.
Is liquid fuel valve closed ?
3 Check the excess flow valve. Yes
No
Reset excess flow safety valve
• Close the main fuel valve.
• Wait for a clicking sound from the
excess flow valve indicating the
valve has reset.
• Slowly open the main fuel valve.
Perform Preliminary Test before
proceeding to Step 4.
Is excess flow valve tripped and closed?
4 Check fuelock supply voltage. Yes
No
12 volt fuelock activation circuit is
open, shorted to ground or the GCP
module is faulty. Check wiring,
connectors and fuses for possible
cause.
Go to Step 5.
• Key OFF.
• Disconnect Fuelock connector from harness.
• Key ON.
• Using a high impedance DVOM, check for 12 volt supply
at the harness connector.
Is the voltage less than 11.5 volts?
5 Check primary fuel pressure to regulator. Yes
No
Fuel filter element may be clogged,
inspect and/or replace the fuel filter as
described in section 475F-1. Repeat
test steps 4-5, if pressure is still less
than specified the fuelock is faulty.
Replace the fuel lock.
Go to Step 6.
• Using Woodward WTK-1 test kit, install the primary
pressure gauge as described in section 475G-1.
• Key ON.
Is the pressure less than "X" psi?
5 Check for icing or freezing of the Regulator. Yes
No
The presence of ice on the converter
without the engine cranking, indicates
the possibility of a fuel leak past the
primary seat of the converter. See
section 475R-1 for service of the
converter.
Go to Step 6.
• Key ON.
• Check for ice or frost build up on the converter casing and
outlet port.
• Key OFF.
Is ice present?
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