How you store your generator between uses determines how reliably it starts when you actually need it. The majority of generator service calls — failed starts, rough running, carburetor problems — trace back directly to improper storage. Follow these steps and your generator will start on the first or second pull after months of storage.
The Core Problem: Fuel Degradation
Modern gasoline contains ethanol — typically 10% in the United States. Ethanol attracts moisture from the air and separates from the gasoline over time, a process called phase separation. This leaves gummy, varnish-like deposits in the carburetor jets and fuel passages. These deposits are the most common cause of generator starting failures after storage.
Standard gasoline begins to degrade noticeably after 30 days. With ethanol-blend fuel (E10), the degradation begins even faster in humid environments.
Method 1: Fuel Stabilizer (Storage Under 12 Months)
For storage periods under 12 months, add a quality fuel stabilizer to fresh gasoline before storing the generator.
Steps
- Add fuel stabilizer to fresh gasoline in the generator tank — follow the stabilizer manufacturer ratio (typically 1 oz per gallon)
- Run the generator for 10–15 minutes to distribute the stabilized fuel through the entire fuel system, including the carburetor
- Allow the generator to cool, then shut it off
- Change the oil before storage — used oil contains combustion acids that degrade engine components during storage
- Remove and inspect the spark plug — apply a small amount of engine oil to the cylinder through the plug hole to prevent rust
- Clean the air filter or replace it if dirty
- Store in a cool, dry location away from direct sunlight and moisture
Method 2: Drain the Fuel (Storage Over 12 Months)
For long-term storage, completely draining the fuel system is more reliable than stabilizer for periods over 12 months.
Steps
- Run the generator until it runs out of fuel naturally, or drain the tank manually
- Restart the generator without adding fuel and let it run until it stops — this removes fuel from the carburetor bowl
- Remove the carburetor drain screw if present and drain any remaining fuel from the bowl
- Change the oil before storage
- Treat the cylinder and spark plug as described in Method 1
- Store in a dry location
Battery Maintenance (Electric Start Models)
The 12V battery on electric start generators will self-discharge during storage. A dead battery means no electric start when you need the generator in an emergency. Connect the battery to a battery maintainer — a low-current trickle charger designed for storage — during any storage period longer than 30 days.
Most generator batteries last 2–3 years. Replace the battery proactively at the 2-year mark rather than waiting for it to fail during an outage.
Ideal Storage Conditions
- Location: Dry, well-ventilated area — garage, shed, or storage building
- Temperature: Cool and stable — avoid spaces with extreme temperature swings
- Cover: Use a generator cover or heavy-duty tarp to protect from dust and moisture
- Position: Keep the generator level to prevent oil from migrating into areas where it does not belong
- Fuel containers: Store fuel in approved containers away from ignition sources
Monthly Storage Routine
Even with proper storage, run your generator at least once per month under load. A 30-minute monthly run with a realistic load keeps fuel circulating, charges the battery, exercises the engine components, and confirms the generator is ready for actual use. It also gives you advance warning of any developing problems before an emergency reveals them.
Pre-Season Checklist
At the start of each storm season — fall for hurricane and winter storm preparation — go through this checklist:
- Check and top up oil level
- Add fresh fuel if stored fuel is more than 30 days old
- Inspect and clean or replace air filter
- Check spark plug condition
- Test electric start battery
- Run under load for 30 minutes
- Test all outlets with a known working device
- Verify fuel in storage containers is fresh