DSG-423 FUEL SYSTEM
04-18
The pinpoint tests below should be performed after the preliminary tests and “Engine Cranks but Will Not Start”
chart Steps 1-3. Any electrical diagnostics should have been performed to eliminate any sensor, GCP or solenoid
valve problems before proceeding
Engine Is Unable To Reach Full Power
Test Step Result Action to Take
1 Check carburetor air valve for binding. Yes
No
Refer to section 475-1 for servicing the
carburetor.
Go to Step 2.
• 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?
2 Check air valve operation. Yes
No
Refer to section 475-1 for servicing the
carburetor.
Go to Step 3.
• 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 accelerating observe the amount of
measured vacuum.
Is the measured vacuum non-linear and outside the
specifications?
2 Check regulator fuel supply. Yes
No
The fuel filter may be restricting flow or
the fuel lock may be intermittent. Go
to Step 3.
Go to Step 4.
• Using Woodward WTK-1 test kit, install the primary
pressure gauge as described in section 475G-1.
• Accelerate to induce symptom.
Is the primary pressure less than "X" psi or fluctuating?
3 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.
Fuel filter element may be clogged,
inspect and/or replace the fuel filter as
described in section 475F-1. Repeat
test Step 2, if pressure is still less than
specified replace the fuel lock and re-
test before moving to Step 4.
• 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?
4 Check regulator operation. Yes
No
Remove the vacuum hose from the
FCV valve to the regulator. If the
pressure is not -1.5 inches of w.c.,
the Regulator is malfunctioning. See
section 475R-1 for service of the
regulator.
Go to ????????.
• Using Woodward WTK-1 test kit, install the primary and
secondary pressure gauge as described in section 475G-
1. (note: the secondary spring color and pressure range)
• Accelerate to induce symptom.
Are the pressures less than "X" specified?
To Next Page
Loading...
Need help?
General
