Generator won't start after sitting? Fix stale gas and a gummed carburetor

Try these first

1. Check the basics: engine switch ON, fuel valve open, oil full, nothing plugged in.
2. Think about how old the gas is. If it's been in there more than a month or two without stabilizer, assume it's stale.
3. Drain the old gas and refill with fresh gasoline.
4. Check the spark plug for fuel, soot or a worn tip.
5. If it still won't start, or only runs on choke, the carburetor needs cleaning.

Why sitting stops a generator

Gas doesn't keep. Honda's manual says fuel can deteriorate and oxidize "in as little as 30 days." Old gas causes hard starting and leaves gum deposits that clog the fuel system. Generac says the same: fuel starts to break down within about a month.

The carburetor is the weak spot. Champion says gas in the tank can last up to a year with stabilizer, but gas left in the carburetor "WILL obstruct and clog the carburetor" if it isn't used or drained within two weeks. That's why a generator that ran fine last season can be dead after one summer in the shed.

Stale gas in the tank

Symptom: It cranks but won't catch, or it fires once and quits.

Why it happens: Stale gas burns poorly, or not at all.

How to check and fix it:

Before you start: engine off and cool, spark plug wire disconnected, outdoors, and no flames or sparks nearby.

1. Turn the fuel valve off.
2. Drain the tank into an approved gas can. Many models have a drain bolt on the carburetor bowl. Champion drains through that bolt, which empties the tank and carburetor together.
3. Tighten the drain bolt again.
4. Refill with fresh gasoline. Honda recommends regular unleaded with no more than 10% ethanol. Briggs & Stratton warns against E15 in small engines.
5. Reconnect the plug wire, open the fuel valve and try to start it.

Take old gas to a local hazardous waste drop-off. Don't pour it on the ground.

A gummed-up carburetor

Symptom: Fresh gas didn't help. Or it only runs with the choke on, runs rough, or surges.

Why it happens: Briggs & Stratton says deposits inside the carburetor "can clog fuel and air passages and reduce performance or stop the engine altogether." The passages are tiny, so a little gum is enough to starve the engine.

How to check and fix it:

Same safety setup: engine off and cool, plug wire off, outdoors, no flames.

1. Check the air filter first. Briggs says to make sure it's installed right, clean, and not soaked with oil.
2. Check the throttle and choke linkages. Briggs notes they can bind or stick when dirty. Work them by hand.
3. Spray carburetor cleaner into the carburetor's air intake and around the linkages. Briggs says this handles many problems "often without even removing the carburetor."
4. Drain the carburetor bowl again to flush out loose gum.
5. Refit the air filter, reconnect the plug wire and try to start it.

If that doesn't work, the carburetor needs a full strip-down, or a replacement. Champion calls this "technically advanced," and Honda sends it to a servicing dealer. Honda's manual also warns that bad storage can mean the carburetor and other fuel parts need servicing "or replaced." If you replace it, get the exact part for your model number.

A fouled spark plug

Symptom: Fresh fuel, clean carburetor, still nothing.

Why it happens: Honda lists a faulty, fouled or wrongly gapped plug as a cause of no start.

How to fix it: With the engine cool and the wire off, remove the plug. Check it, clean or replace it, and set the gap from your manual. Our main won't start guide walks through it.

A dead starter battery

Symptom: On an electric-start model, the button does nothing, or just clicks.

Why it happens: Starter batteries drain in storage. Generac notes electric-start batteries can run down. Champion's manual says to charge the battery fully at least once a month.

How to fix it: Charge the battery, or use the pull cord.

How to store it so this doesn't happen again

Pick one of these, from Honda's and Champion's storage steps:

• Run it dry. Add stabilizer, run it for about ten minutes, then turn the fuel valve off and let the engine run until it stops. Champion recommends this.
• Drain it. Generac recommends draining the tank and running the carburetor dry if you'll store it for more than 30 days.
• Stabilize it. Add fuel stabilizer to fresh gas every time you fill up. Follow the ratio on the bottle.

Then run it for a few minutes every month or so, so you know it works before the next outage.

When to stop and call a pro

Take it to a servicing dealer if:

• A cleaned carburetor still won't let it run.
• You see fuel leaking from the carburetor or the fuel line.
• There's water or rust in the tank.
• It's under warranty. Honda notes its warranty does not cover fuel system damage from neglected storage, so ask the maker first.

Run it outdoors only, 20+ feet from the house: generator carbon monoxide safety.