Generator maintenance consists of the routine inspections, fluid changes, and component replacements necessary to ensure reliable starting and operation. A generator that starts only during an emergency must start on the first attempt, which requires disciplined maintenance during the months or years between uses. The primary maintenance intervals are based on operating hours, typically every 50 to 100 hours for oil changes and every 200 to 400 hours for more extensive servicing. Generator Sizing and Generators provide context for selecting the right unit before maintenance begins.
Oil is the most critical maintenance item. The oil level should be checked before each use, and oil should be changed after the first 5 to 20 hours of operation on a new generator, then every 50 to 100 hours or annually, whichever comes first. SAE 10W-30 oil is standard for most portable generators. The air filter should be cleaned every 50 hours and replaced annually. The spark plug is inspected and cleaned every 100 hours and replaced every 200 to 300 hours. Valve clearance adjustment is recommended every 300 to 500 hours on most engines.
Fuel deteriorates within 30 to 60 days, forming deposits that clog carburetor jets. A fuel stabilizer added to fresh fuel extends storage life to 6 to 12 months. For generators used only for emergency backup, running the carburetor dry after each use prevents varnish buildup. Ethanol-blended fuels absorb moisture and accelerate corrosion. Non-ethanol fuel or premium fuel with stabilizer is preferred. The fuel filter should be replaced annually.
Generators should be exercised under at least 50 percent load for 30 minutes every 30 to 60 days. Light loading, below 30 percent of rated capacity, can cause wet stacking in diesel generators and carbon buildup in gasoline engines. For long-term storage, the fuel is drained, oil is changed, the cylinder is fogged with oil spray, and the generator is stored in a dry, clean location. The battery, if equipped, is placed on a trickle charger. Small Engine Repair covers carburetor and ignition troubleshooting.