18 Generac
®
Power Systems, Inc.
Section 5 — Troubleshooting
Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators
PROBLEM
CAUSE
CORRECTION
Engine won’t crank.
1. 30 amp fuse blown.
1. Replace fuse.
2. Loose or corroded or defective
2. Tighten, clean or replace
battery cables.
battery cables as necessary.
3. Defective starter contactor.
3. Replace contactor.
4. Defective starter motor.
4. Replace starter motor.
5. Dead or Defective Battery.
5. Remove, change or replace battery.
Engine cranks but won't start
1. Out of fuel.
1. Replenish fuel.
2. Fuel solenoid (FS) is defective
2. Replace solenoid.
3. Open Wire #14 from Engine Control
3. Reconnect wire.
circuit board.
4. Spark plugs defective.
4. Clean, regap or replace plugs.
Engine starts hard, runs rough.
1. Flame arrestor (air cleaner) plugged or
1. Clean or replace as needed.
damaged.
2. Plugged fuel line.
2. Unclog fuel line.
3. Defective spark plugs.
3. Clean, regap or replace plugs.
Engine starts then shuts down.
1. Engine oil level is low.
1. Check oil and add oil as needed.
2. Engine is overheated.
2. Check cooling system for leaks.
3. Defective Low Oil Pressure Switch
3. Replace switch.
4. Defective Coolant Temperature Switch
4. Replace switch.
5. Defective Control Module circuit board.
5. Replace board.
6. Coolant Level is Low.
6. Repair leak - Add coolant.
7. Defective Low Coolant Level Switch
7. Replace Switch.
Auto/Off/Manual Switch at OFF,
1. Defective Auto/Off/Manual switch
1. Replace switch.
engine continues to run
2. Open/disconnected wire #15A between
2. Reconnect/close wire.
Auto/Off/Manual switch and Control
Module circuit board.
3. Defective Control Module circuit board
3. Replace board.
No AC output from generator.
1. Check main line circuit breaker.
1. Reset to ON or CLOSED.
2. Check circuit breaker & fuses.
2. Reset and replace, if necessary.
3. Transfer switch set to NORMAL position
3. Set to GENERATOR position.
4. Generator internal failure.
4. Contact an Authorized Generac
facility.
5. Thermal circuit breaker open.
5. Auto-reset - Wait 5 min. and
attempt restart.
PERIODIC REPLACEMENT PARTS
Part Name
Generac’s Part Number
Oil Filter
# 0A45310244
Radiator Cap
# 046627
Air Cleaner
# 059402
Spark Plug
# 0A45310275
TROUBLESHOOTING POINTS
