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Generac 20kW Owner's Manual: Troubleshooting; Troubleshooting Guide

Generac standby generator owner's manual.

Engine won't crank.
Engine cranks but won't start
Engine starts hard, runs rough.
Engine starts then shuts down.
engine continues to run
No AC output from generator.
Standby Generator Sets


1. 15 amp fuse blown.
2. Loose or corroded or defective
battery cables.
3. Defective starter contactor.
4. Defective starter motor.
5. Dead or Defective Battery.
6. 5 amp fuse blown.
1. Out of fuel.
2. Fuel solenoid (FS) is defective
3. Open Wire #14A from Engine Control
circuit board.
4. Spark plugs defective.
5. Door on tank not closed.
1. Flame arrestor (air cleaner) plugged or
2. Plugged fuel line.
3. Defective spark plugs.
4. Fuel pressure incorrect.
1. Engine oil level is low.
2. Engine is overheated.
3. Defective Low Oil Pressure Switch
4. Defective Coolant Temperature Switch
5. Defective Control Module circuit board.
6. Coolant Level is Low.
7. Defective Low Coolant Level Switch
1. Defective AUTO/OFF/MANUAL switch
2. Open/disconnected wire #15A between
AUTO/OFF/MANUAL switch and Control
Module circuit board.
3. Defective Control Module circuit board
1. Check main line circuit breaker.
2. Check circuit breaker & fuses.
3. Transfer switch set to NORMAL position
4. Generator internal failure.
5. Thermal circuit breaker open.
*Contact the nearest Authorized Dealer for assistance.
1. Replace fuse.
2. Tighten, clean or replace
battery cables as necessary.
3. Replace contactor.*
4. Replace starter motor.*
5. Remove, change or replace battery.
6. Replace fuse.*
1. Replenish fuel.
2. Replace solenoid.*
3. Reconnect wire.
4. Clean, regap or replace plugs.
5. Close door on tank.
1. Clean or replace as needed.
2. Unclog fuel line.
3. Clean, regap or replace plugs.
4. Confirm fuel pressure to regulator is as
recommended in SPECIFICATIONS.
1. Check oil and add oil as needed.
2. Check cooling system for leaks.
3. Replace switch.*
4. Replace switch.*
5. Replace board.*
6. Repair leak - Add coolant.
7. Replace Switch.*
1. Replace switch.*
2. Reconnect/close wire.
3. Replace board.*
1. Reset to ON or CLOSED.
2. Reset and replace, if necessary.
3. Set to GENERATOR position.
4. *
5. Auto-reset - Wait 5 min. and
attempt restart.

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