A portable generator that won't start during a power outage is worse than no generator at all — it gives you false confidence. The most common reason generators fail to start after storage is the same every time: fuel system problems. Here's how to store yours so it's ready when you need it.
The Generator Storage Problem
Portable generators sit unused for months or even years between power outages. During that time, three things happen:
- Fuel degrades and forms varnish that clogs the carburetor
- Oil settles and moisture condenses inside the engine
- Batteries discharge (for electric-start models)
Any one of these can prevent the generator from starting. All three together guarantee it won't.
Short-Term Storage (1–3 Months)
If you'll use the generator within a few months:
1. Add Fuel Stabilizer
Add fuel stabilizer to a full tank of fresh fuel. Run the generator for 10–15 minutes under a small load (plug in a work light or fan) so treated fuel flows through the entire fuel system. See our fuel stabilizer guide for details.
2. Change the Oil
Change the oil after running the generator, while it's warm. Old oil contains acids and moisture that can corrode bearings during storage.
3. Clean the Air Filter
Remove and clean the air filter. A dirty filter left in place will harden and restrict airflow.
4. Store in a Dry, Covered Location
Store the generator in a shed, garage, or under a fitted cover. Never store it exposed to rain or direct sun.
Long-Term Storage (3+ Months)
For storage longer than three months, take additional steps:
1. Drain the Fuel Completely
For long-term storage, draining is more reliable than stabilizer. Run the generator until it runs out of fuel. Then:
- Drain the fuel tank using a siphon pump
- Loosen the carburetor drain screw and drain the carburetor bowl
- Dispose of the old fuel properly
2. Fog the Cylinder
Remove the spark plug and spray a small amount of fogging oil (or a tablespoon of clean engine oil) into the cylinder. Pull the starter cord slowly a few times to distribute the oil. This prevents the cylinder walls from rusting during long storage. Reinstall the spark plug.
3. Disconnect the Battery
For electric-start generators, disconnect the battery and store it separately. Put it on a trickle charger or check it every 2–3 months and recharge if voltage drops below 12.4V.
4. Plug the Exhaust and Intake
Stuff a clean rag into the exhaust outlet and cover the air intake. This prevents insects and rodents from nesting inside the engine during storage. Remove these before starting.
5. Store Elevated
Store the generator on a shelf or pallet, not directly on a concrete floor. Concrete can cause condensation and the generator can absorb moisture from the ground.
Inverter Generators (Honda EU, Champion Inverter, etc.)
Inverter generators have additional electronics that need protection. Follow the same fuel and oil steps, but also:
- Store in a dry location — humidity can corrode the inverter board
- Keep the unit level to prevent oil from pooling in the cylinder
- Run the generator for 15–20 minutes every 2–3 months even if you don't need power, to keep the carburetor seals from drying out
Before You Need It: The Test Run
The worst time to discover your generator won't start is during a storm. Every 2–3 months, pull it out, add fresh fuel, and run it for 20–30 minutes under a moderate load. This:
- Recharges the battery
- Circulates oil through the engine
- Keeps the carburetor from drying out
- Confirms it actually works
If it won't start during a test run, search your generator model and symptom on Lil Engine for a specific troubleshooting guide.
The Bottom Line
Generator storage is about preventing three things: fuel degradation, moisture damage, and battery discharge. Handle all three and your generator will start reliably for years. Ignore them and you'll be rebuilding a carburetor — or buying a new generator — after the next outage.