Guardian 4721, Repair Manual

Page: 85 / 115

DC CONTROL
LIQUID COOLED
ENGINE UNITS
SECTION 4.3
TROUBLESHOOTING FLOW CHARTS
PART 4
Page 81
REPAIR
ENGINE AS
NEEDED
RESET TIMING
AS NECESSARY
CLEAN, REGAP,
OR REPLACE AS
NECESSARY
REPAIR OR
REPLACE AS
NECESSARY
REPAIR OR REPLACE
AS NECESSARY
BAD
GOOD
TEST 20 - CHECK
ENGINE
COMPRESSION AND
ENGINE CONDITION
REPLACE
BAD
SOLENOID
BAD
REPLACE
GOVERNOR BOARD
OR STEPPER MOTOR
AS NECESSARY
BAD
GOOD
TEST 11 - CHECK
FUEL SUPPLY
AND PRESSURE
TEST 18 - CHECK
DC VOLTS AT
TERMINAL 14 OF
TB1
TEST 19 - TEST
FUEL SOLENOID
(FS)
TEST 12 - CHECK WIRE
14 OUTPUT TO IGNITION
AND GOVERNOR BOARD
GOOD
GOOD
TEST 13 - BENCHMARK
TESTING, DISTRIBUTOR
INTERNAL COMPONENTS
SECTION 2.4, TEST 13 -
CHECK AND ADJUST
GOVERNOR BOARD AND
STEPPER MOTOR
TEST 14 - INSPECT
DISTRIBUTOR CAP
AND ROTOR
GOOD
GOOD
GOOD
TEST 15 - CHECK
SPARK PLUGS
GOOD
BAD
BAD
FIND AND CORRECT
CAUSE OF NO FUEL OR
LOW PRESSURE
Problem 3 - Engine Cranks but Won’t Start
REPLACE
CONTROL
BOARD
BAD
BAD
BAD
BAD
REPLACE BAD
WIRES
TEST 16 - CHECK
IGNITION WIRES
TEST 17 - CHECK
IGNITION TIMING
GOOD BAD
GOOD
TEST 21 - CHECK
GENERATOR
MAIN LINE
CIRCUIT
BREAKER
TEST 22 - CHECK
SENSING TO
CONTROL CIRCUIT
BOARD
TEST 24 - CHECK
VOLTAGE AT
TERMINAL LUGS
E1/E2
GO TO PROBLEM 1 IN
SECTION 3.3
GO TO "TROUBLESHOOTING
FLOWCHARTS" 1 IN SECTION 2.3
TEST 23 - GROUND
CONTROL BOARD
TERMINAL 23
GOOD
GOOD, BUT
NO
TRANSFER
NO TRANSFER
OPEN OR BAD
BAD
BAD
Problem 4 - Engine Cranks and Starts but Won’t Transfer to Standby
REPLACE CMA
CIRCUIT BOARD
TRANSFERS TO
STANDBY
CLOSE CIRCUIT
BREAKER OR
REPLACE IF BAD
GOOD GOOD
TEST 21 - CHECK
GENERATOR MAIN LINE
CIRCUIT BREAKER
TEST 26 - CHECK
VOLTAGE AT
CMA TERMINALS
N1A/N2
GO TO PROBLEM 3 IN
SECTION 3.3
TEST 27 - TEST
SENSING
TRANSFORMER
GOOD
BAD
BAD
BAD
Problem 5 - Engine Starts and Transfer Occurs When Utility Power is Available
REPLACE
CONTROL BOARD
AND TEST AUTO
OPERATION
REPLACE DEFECTIVE
TRANSFORMER
DETERMINE CAUSE OF LOW OR
NO UTILITY SOURCE VOLTAGE
AND CORRECT