Generator Won't Start After Sitting? Here's Your Step-by-Step Revival Guide

Storm's coming. Power might go out. You drag the generator out of the garage where it's been sitting since last summer. Pull the cord. Nothing. Pull again. Nothing.

Deep breath. This happens to everyone. Generators that sit for more than a month are basically hibernating bears — they need a nudge to wake up.

Step 1: Check the Fuel

Gasoline goes stale in as little as 30 days. After 3-6 months, it turns into a varnish-like substance that clogs the carburetor and fuel lines.

What to do:

• Drain the old fuel completely. Don't run it through — drain it out the fuel valve or siphon it.
• Fill with fresh gasoline.
• Add fuel stabilizer (Sta-Bil or similar). Next time, add this before storage.

Step 2: Check the Oil

Most generators have a low-oil shutoff. If the oil level is below the sensor, the engine won't start as a safety measure — no warning, no error code, just... nothing.

Pull the dipstick. If it's low or the oil looks like chocolate milk (water contamination), drain and refill with fresh oil. Check your manual for the right weight — usually 10W-30.

Step 3: The Carburetor

If you had old fuel sitting in there, the carburetor jets are probably gummed up. Two options:

1. Quick fix: Spray carburetor cleaner into the air intake while cranking. Sometimes this is enough to dissolve the varnish and get things moving.
2. Real fix: Remove the carburetor bowl (usually one bolt), clean the jet with a thin wire or compressed air, and reassemble. Takes 20-30 minutes.

Step 4: Spark Plug

Pull the spark plug and look at it. You're checking for:

• Fouling — black, wet, or oily deposits. Clean with a wire brush or replace ($3-8).
• Gap — should be about 0.028-0.031" for most generators. Use a gap tool.
• Spark test — hold the plug against the engine block, pull the cord, and look for a blue spark. No spark = bad ignition coil (less common).

Step 5: The Choke

Make sure the choke is in the correct position for a cold start — usually the CLOSED or START position. Run it there for 30 seconds, then gradually open it as the engine warms up.

Prevention for Next Time

• Add fuel stabilizer before storage. Always.
• Run the generator for 15-20 minutes every month — even if you don't need power.
• Shut off the fuel valve and run the engine until it dies. This empties the carburetor.
• Store in a dry place with a cover.