Home standby generator will not start during an outage: do not keep clearing alarms. Record the controller, confirm AUTO, verify fuel availability and remove household load before one controlled restart. Photograph the controller and status light, and check that it is in AUTO before doing anything else.
What this covers
- Residential automatic standby generators with a controller display or status light
What it does not cover
Differential
Likely causes of “Home standby generator will not start during an outage”, and how to tell them apart
- 1
The controller is not in AUTO or is showing an alarm
What separates it The generator does not crank when utility power fails and the controller shows a warning or is set to OFF or MANUAL.
How to confirm Photograph the controller and status light, and check that it is in AUTO before doing anything else.
- 2
The fuel supply is off, empty or interrupted
What separates it The engine cranks but does not fire, or does not crank at all, and the gas or LP valve is closed or the tank is low.
How to confirm Check the external fuel shutoff and the LP tank level or the gas supply without opening the cabinet.
- 3
The starting battery is weak or its connections are loose
What separates it The generator clicks or cranks slowly and the battery indicator is low, especially after a cold spell.
How to confirm Check the battery status on the controller as the manual describes.
- 4
Maintenance is overdue or an airflow path is blocked
What separates it A generator that has not been serviced for years, or one whose intake or exhaust is blocked by snow, leaves or debris.
How to confirm Look at the exterior vents and the last service date.
Before you touch a setting
Record this first — changing settings destroys the evidence
- A photograph of the controller display and the status light or alarm.
- The fuel type, the tank level and the last exercise or service date.
- Whether it cranks, and for how long.
Try in this order
0 of 4 completedCapture the exact state
ReversiblePhotograph controller/status light and note fuel, last exercise and cranking.
Separate the likely fault domains
ReversibleCheck AUTO, battery status, external fuel shutoff, LP supply, airflow and maintenance.
Correct only the proven, accessible condition
ReversibleCorrect an obvious external condition, then follow the exact alarm-clear and unloaded restart once.
Verify once before going farther
ReversibleConfirm stable manual operation before restoring loads one at a time.
Stop boundary
When this stops being a self-service repair
- !Do not keep clearing alarms. Follow the exact alarm-clear and one unloaded restart from the manual, and stop if it fails.
- !Confirm stable manual operation before restoring household loads one at a time.
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Should I keep trying to restart the generator?+
No. Repeated restarts can flood the engine or drain the battery. Record the alarm, remove the load and try one controlled restart.
Why won't the generator start in an outage?+
A weak battery or fuel problem is common.