Generator Maintenance Checklist: How to Keep Your Portable Generator Running for Years

A portable generator is insurance. You buy it for the moments when everything else fails — a power outage, a storm, a job site with no grid power. The problem is most generators sit in a garage or storage unit for months at a time, and when you pull the cord in an emergency, they won't start.

The reason is almost always lack of maintenance. Here's the complete checklist to keep your generator reliable year after year.

Before Every Use

• Check the oil level with the dipstick — add oil if low. Most portable generators take SAE 10W-30

• Inspect the fuel level. If the machine has been sitting, use fresh fuel (see fuel storage section below)

• Check the air filter — tap it clean or replace if heavily soiled

• Inspect the spark plug for fouling or carbon buildup

• Check for any fuel or oil leaks before starting

• Ensure the generator is placed on a level surface and at least 20 feet from any structure (carbon monoxide risk)

After Every 25 Hours of Use (or Monthly During Season)

• Change the engine oil — use the manufacturer-specified grade. For most Firman generators this is SAE 10W-30

• Clean or replace the air filter element

• Check and clean the spark plug — replace if the electrode is worn or the gap is incorrect (typically 0.028–0.031 inches)

• Inspect all fuel lines and connections for cracks or wear

• Test and reset the GFCI outlets if equipped

After Every 100 Hours of Use (or Seasonally)

• Replace the spark plug — even if it looks okay, a fresh plug ensures reliable starting

• Replace the air filter — don't just clean it

• Change the fuel filter if your model has an inline filter

• Inspect the carburetor for varnish buildup — ethanol in fuel causes this in machines that sit unused

• Check and re-torque all bolts, especially the engine mounting bolts

• Load test the generator by running it at 50–75% capacity for 30 minutes

Annual Service (Before Storage Season)

• Drain the fuel tank and run the carburetor dry — stale fuel is the number one cause of no-start situations

• OR add fuel stabilizer to a full tank and run the engine for 10 minutes to circulate it through the system

• Change the oil while the engine is warm so it drains fully

• Inspect the battery in electric-start models — replace if it won't hold a charge

• Test the remote start system if equipped (like the Firman P06707)

• Inspect and clean the exhaust system

• Store with the fuel valve closed and the carburetor drained if possible

Fuel Storage Tips

Ethanol-blended gasoline (E10 or higher) begins to degrade in as little as 30 days, leaving behind varnish that clogs carburetors. For generators that won't be used regularly:

• Use ethanol-free fuel if available in your area (often sold as 'recreational fuel' or 'premium non-ethanol'

• Add a quality fuel stabilizer (like Sta-Bil) if using ethanol-blend fuel and storing for more than 30 days

• Never store a generator with untreated fuel for more than 60 days

When to Call a Professional

Some issues go beyond routine maintenance:

• Generator starts but voltage output is low or unstable — likely an AVR (automatic voltage regulator) issue

• Carburetor won't respond to cleaning — may need replacement

• Engine burns through oil quickly — worn rings or valve seals

• Generator trips circuit breakers under moderate load — could be a capacitor or alternator issue

For these, consult a certified small engine technician.

Keep a Log

The simplest thing you can do is write down every service date and hour reading in a small notebook kept with the generator. It makes troubleshooting easier, increases resale value, and helps you stay on schedule.

Looking for a reliable portable generator? Browse our Firman generator lineup at ironva.com — all backed by manufacturer warranty and shipped free nationwide.