Engine distributors DSG-423 User Manual

DSG-423 FUEL SYSTEM
04-22
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 Backfires
Test Step Result Action to Take
1 During Start-up, check for fuel lock leakage (not
closing).
Yes
No
This would indicate the fuel lock is not
closing and allowing fuel to pass in the
OFF position. Replace the Fuel Lock.
Go to Step 2.
• Close the tanks main fuel valve.
• Using Woodward WTK-1 test kit, install the primary
pressure gauge as described in section 475G-1.
• Key OFF.
• Slowly open the main fuel valve
Do you measure any fuel pressure?
2 With engine running, 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, if pressure is still less than
specified the fuelock is faulty.
Replace the fuel lock.
Go to Step 3.
• With the primary pressure gauge installed as described in
section 475G-1, measure the supply pressure.
• Key ON, Engine Running.
Is the pressure less than "X" psi?
3 With engine running, 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 Step 4.
• 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)
• With the engine at idle or accelerate to induce symptom.
Are the pressures less than "X" specified?
4 Check FCV operation. Yes
No
This would indicate the engine is
experiencing a momentary mixture
change. Possible causes:
• Faulty FCV valve connection or
vacuum leaks, go to Step 5.
• GCP fault.
Go to Step 6.
• At idle or accelerate Engine to induce symptom.
• Disconnect the vacuum hose from the FCV valve to the
regulator
Is the backfire present with the hose disconnected?
5 Check FCV Supply Voltage. Yes
No
12 volt FCV circuit is open, shorted to
ground or the GCP module is faulty.
Check wiring, connectors and fuses
for possible cause.
Go to Step 6.
• Key OFF.
• Disconnect FCV connector from harness.
• With engine at idle.
• Using a high impedance DVOM, check for 12 volt supply
at the harness connector.
Is the voltage less than 11.5 volts?

Engine distributors DSG-423 Specifications

General

Brand	Engine distributors
Model	DSG-423
Category	Engine
Language	English