Generator won't start after running out of gas? Here's why and what to do

Try these first

1. Let the engine cool down before you add gas.
2. Refuel with fresh gas, outdoors.
3. Unplug everything from the generator.
4. Check that the fuel valve and the fuel cap vent are ON.
5. Set the choke to full, as for a cold start.
6. Give it several firm pulls. The carburetor has to refill first.

Why it's harder to start after running dry

When the tank runs empty, the engine uses up the last fuel in the line and the carburetor bowl, then stops. Before it can start again, fuel has to flow back down the line and refill the bowl. Until it does, the engine has nothing to burn.

Champion's manual builds this into its normal recoil start. It calls it pull-to-prime: with full choke, pull the cord one or two times "until you feel a few combustion pulses." Then move the choke to RUN and pull again. If the engine doesn't start on that pull, go back to full choke and prime again.

The engine also cooled down while you were refueling. So treat it as a cold start. Honda's steps are to close the choke for a cold engine, then open it gradually as it warms up.

Refuel safely first

Running out of gas usually happens in the middle of an outage, often at night. Rushing a refuel is how fires start.

• Turn it off and let it cool. NFPA says to turn generators off and let them cool before refueling, and never to refuel one that's hot. OSHA warns that fuel spilled on hot engine parts can ignite.
• Refuel outdoors, where the generator runs. Honda says to handle fuel only outdoors and to wipe up spills right away.
• Don't overfill. Champion says to leave room in the tank for the fuel to expand.
• Use a flashlight, not a lighter or a candle.

Unplug the loads before you restart

If the tank ran dry while things were plugged in, the generator stopped with a load on it. Leave that load on, and it can stop the restart.

• Champion's troubleshooting table lists "unit loaded during start up" as a cause of no start. Its manual says to "never start or stop the generator with electrical devices plugged in or turned on."
• Generac says generators need to stabilize and warm up before you add appliances.

Unplug everything. Start it, let it run a few minutes, then plug things back in one at a time. If it runs but nothing gets power, see generator running but no power.

Still won't start? Work through these

The carburetor is air-locked

Symptom: Fresh gas in the tank, but the engine acts as if there's none. No combustion pulses, even after many pulls.

Why it happens: Air trapped in the bowl can stop fuel from flowing in. WEN's troubleshooting table lists "carburetor is air locked" as a cause of an engine that won't start.

How to fix it: WEN's steps are to turn the engine switch OFF, remove the bolt from the bottom of the carburetor, and take off the bowl "to allow it to reset." Then refit the bowl and the bolt. Do this with the engine cool, outdoors, with a rag and an approved container to catch the fuel. If your manual doesn't cover the bowl bolt, skip this step and call a servicing dealer.

It pulled in dirt or water from the bottom of the tank

Symptom: It started, sputtered, and died. Or it now only runs on choke.

Why it happens: Water, dirt and old fuel settle at the bottom of the tank. Running the tank to empty can pull them into the carburetor. Champion's manual warns that ethanol blends "can eventually separate, leaving water or a watery goo in the tank, fuel valve and carburetor." On gravity-fed models, that goo can be drawn into the carburetor.

How to fix it: Drain the tank and the carburetor bowl into an approved can, then refill with fresh gas. If it only runs on choke afterward, see generator only runs on choke.

The spark plug is wet

Symptom: It smells strongly of gas after a lot of pulls on full choke.

Why it happens: Too many pulls on full choke can flood the engine. Honda lists a "spark plug wet with fuel (flooded engine)" as a cause of no start.

How to fix it: With the engine off and cool and the plug wire off, take the plug out. Honda's fix is to dry it and put it back. Then try again with less choke.

Something else is wrong

Low oil, a dead starter battery or stale gas can still stop it, the same as any other day. Our main generator won't start guide walks through those in order.

Does running out of gas damage a generator?

None of the manuals we read list running out of gas as a fault in itself. Some makers even tell you to run the carburetor dry on purpose before storage. Champion's storage steps have you close the fuel valve and let the engine run "until fuel starvation has stopped the engine." That is done with no load plugged in.

The harm comes from what happens around it:

• Loads left plugged in when it stops and restarts, which Champion warns against.
• Gunk pulled from the bottom of the tank, which can clog the carburetor.
• Refueling while it's hot, which is a fire risk.

How to avoid running dry

• Know your runtime. A full tank lasts longer at light load than at heavy load. Our 5 gallons of gas runtime guide shows the maths.
• Refuel before it's empty. Shut it down, let it cool, and top it up at a planned time, not when it stalls.
• Plan a cool-down window. Unplug, turn it off, and wait before you refuel. Honda's manual says to stop the engine and let it cool before handling fuel.
• Keep fresh fuel. Store gas in an approved can, away from your living space, with stabilizer added.

When to call a pro

Have it checked by a servicing dealer if:

• It won't start after fresh gas, full choke, a dry plug and no load.
• Fuel leaks from the carburetor or the air box after refueling.
• The pull cord locks up and won't move.

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