The #1 reason generators fail during outages: They haven't been run in months, the gasoline has gone stale, and the carburetor is gummed up. A 30-minute quarterly exercise run prevents 90% of unplanned startup failures.
Before Every Use
- ☐ Check engine oil level — add if below the full mark
- ☐ Check fuel level — fill with fresh gasoline (under 30 days old) or stabilized fuel
- ☐ Inspect air filter — tap out dust; replace if dark or clogged
- ☐ Check for fuel or oil leaks around the engine and connections
- ☐ Ensure the generator is at least 20 feet from any doors, windows, or vents
- ☐ Confirm CO detectors are working inside the home
- ☐ Verify total expected load is within rated generator capacity
Monthly (or Every 30 Hours of Use)
If you run your generator regularly during a long outage, these checks apply by the hour-count, not calendar month.
- ☐ Check oil level and condition — oil that looks dark or milky should be changed immediately
- ☐ Inspect air filter — replace if dirty (paper filters cannot be cleaned effectively)
- ☐ Check spark plug(s) for fouling or gap erosion
- ☐ Inspect fuel lines and connections for cracks or seeping
- ☐ Clean debris from around the generator and cooling vents
Quarterly (Every 3 Months)
The quarterly exercise run is the single most important maintenance task for a generator that sits idle most of the year.
Exercise Run Procedure
- Fill the fuel tank with fresh gasoline (or stabilized fuel).
- Start the generator and let it warm up for 2–3 minutes unloaded.
- Connect a real load — a space heater, shop light, or hair dryer — equivalent to roughly 50% of the generator's rated wattage.
- Run under load for 30 minutes.
- Shut down normally and let it cool for 10 minutes.
- Check oil level again after the run. Top off as needed.
- ☐ Perform exercise run (30 min at ~50% load)
- ☐ Check battery (electric-start models) — test voltage or charge if weak
- ☐ Inspect wheel bolts and frame hardware for looseness
- ☐ Verify all outlets function with a plug-in light or device
- ☐ Ensure fuel stabilizer has been added to tank if generator will sit again for more than 30 days
Annual (Every 100 Hours or Once Per Year)
Annual maintenance is the generator equivalent of a car's annual service — it keeps the engine healthy for years of reliable operation.
- ☐ Change the engine oil — use the grade specified in the manual (SAE 10W-30 is common)
- ☐ Replace the air filter — even if it looks clean, annual replacement is cheap insurance
- ☐ Replace the spark plug(s) — a new plug improves starting reliability and fuel economy
- ☐ Replace the fuel filter (if equipped) — prevents carburetor contamination
- ☐ Inspect and clean the carburetor — especially if the generator sat without stabilized fuel. A gummed carburetor is the #1 cause of hard starts.
- ☐ Test the battery (electric-start models) — replace if it holds less than 12.4V under load
- ☐ Check and tighten all bolts and fasteners — vibration loosens everything over time
- ☐ Test the transfer switch (if installed) — simulate a power failure to verify automatic switching
- ☐ Record the service date and engine hours in a maintenance log
Seasonal Prep
Before Hurricane/Storm Season (Spring)
- Perform full annual service if not done in the past 12 months.
- Fill and stabilize the fuel tank.
- Stock 20–30 gallons of additional stabilized gasoline.
- Test the generator under load.
- Verify CO detectors are functioning.
- Know your extension cord routing plan before you need it.
Winterizing (Pre-Winter)
- If storing the generator through winter without use, drain the carburetor bowl completely or run the carburetor dry (run the engine until it starves for fuel) to prevent gum buildup.
- Alternatively, fill the tank and add a double dose of fuel stabilizer — this is the easier option and prevents tank corrosion from moisture.
- Store in a clean, dry location out of direct weather. A generator cover is useful but must allow air circulation to prevent condensation.
- Disconnect the battery or use a battery tender if storing for more than 2 months.
Spring Startup After Storage
- Check oil level before starting.
- If the fuel was drained, add fresh gasoline.
- Check that the choke and throttle controls move freely.
- Start and run a short exercise cycle to verify all systems work.
- If the generator won't start after winter, the carburetor likely needs cleaning.
Oil Selection Guide
Using the wrong oil grade is a common mistake. Always check your owner's manual, but here are the typical recommendations:
| Temperature Range | Recommended Oil Grade |
|---|---|
| Above 40°F (4°C) | SAE 30 |
| 0°F to 100°F (-18°C to 38°C) | SAE 10W-30 (most common) |
| Below 40°F (4°C) | SAE 5W-30 |
| Synthetic (any temp) | 5W-30 full synthetic — best cold-start protection |
Use the oil capacity specified in your manual. Most 5,000–8,000W generators hold 0.6–0.7 quarts (about 20 oz). Never overfill — excess oil can be drawn into the combustion chamber and damage the engine.
Before your next maintenance run, verify your generator is properly sized for your load. An oversized or undersized generator is harder on the engine during exercise runs.
Check Your Generator Size →