A generator is the only appliance you own that is expected to sit idle for a year and then perform perfectly on the worst night of the year. Nothing else in the house is asked to do that. The machines that fail are almost never worn out; they are neglected, and the neglect is nearly always in the fuel system.
Monthly: the exercise run
Standby units handle this themselves with a weekly or biweekly self-test, typically 10 to 20 minutes. Check that yours is actually running by noting the day and time in your calendar and listening for it once.
Portables need you to do it. Once a month, start the unit and let it run 15 to 20 minutes under load, not at idle with nothing plugged in. A couple of work lights or a space heater is enough. Loaded running gets the engine up to temperature, burns off condensation in the crankcase, keeps the carburettor wet with fresh fuel, and exercises the starter and the battery. An unloaded run does about half of that.
While it runs, check the oil level, look underneath for drips, and listen for anything that has changed since last month.
Every 50 to 100 hours, or annually
- Oil and filter. The single most important item. Small air-cooled engines share oil with nothing and hold very little of it, so contamination concentrates fast. First change on a new unit is often at 20 to 30 hours; after that, follow the manual, and change it annually regardless of hours.
- Air filter. Inspect it every time you change oil. Foam elements get washed and lightly re-oiled; paper elements get replaced. A restricted filter richens the mixture and coats the plug.
- Spark plug. Inspect, clean and re-gap yearly, replace every couple of seasons. The colour of the electrode tells you whether the engine is running rich, lean or right.
- Battery. Standby generators start on a battery and a dead battery is the most common reason one fails to start. Most last three to five years. Load-test it annually before storm season and replace it on age rather than waiting for a failure.
- Valve clearance. Every few hundred hours on most small engines. A hard-starting engine that once started easily often just needs the valves set.
Seasonal: before storm season
Pick a date you will remember, ideally a month before your region's risk window, and run through this list:
- Full exercise run under load for 30 minutes. Confirm voltage and frequency if you have a meter.
- Fresh fuel with stabiliser. Rotate anything older than three months into a vehicle.
- Inspect every cord end for cracked insulation and bent pins. Cords fail more often than generators.
- Test the transfer switch or interlock through a full cycle so you remember the sequence in the dark.
- Check the CO alarms inside the house.
- Confirm the wheel kit and the handles still work, and that you can move the unit to its outdoor spot alone.
Storage: the part that ruins carburettors
For anything sitting more than 30 days, choose one of two approaches and commit to it.
Run it dry. Close the fuel valve with the engine running and let it consume everything in the bowl until it stalls. Nothing is left to evaporate and leave varnish behind. This is the better method for gasoline units stored a long time.
Or fill and stabilise. Top the tank so there is minimal air space for condensation, add stabiliser at the labelled dose, and run the engine five to ten minutes so treated fuel reaches the carburettor. This suits units you exercise monthly.
What ruins engines is the third option people default to: leave a half-full tank of untreated pump gas alone for eleven months. Propane sidesteps this entirely, which is one of the quieter arguments for a dual-fuel machine.
Standby-specific items
Standby generators live outdoors permanently and have their own list. Keep at least three feet clear on all sides for airflow and service access, and keep the enclosure free of leaves, snow drifts and nesting rodents, who find a warm enclosure irresistible and chew wiring. Check the coolant on liquid-cooled units. Confirm the controller has no stored fault codes, and note that the annual service most manufacturers require to keep the warranty valid is usually not optional paperwork.
Keep a log
A card taped inside the enclosure with date, hour meter reading and what was done takes ten seconds to update and answers every future question: when the oil was last changed, how old the battery is, whether the hard start last winter was a one-off. It also raises resale value, and it is what a service technician will ask for first.
When to call someone
Fuel system cleaning, valve adjustment, voltage regulator faults, controller errors on a standby unit and anything involving the transfer switch are jobs for a technician. Persistent low or high output voltage in particular is worth stopping for: it damages everything plugged into it, and it is not a symptom you should test by connecting your furnace. If you need someone local, our state-by-state directory lists repair shops and installers by city. For general household electrical safety background, OSHA's electrical resources are a solid non-commercial reference.