Generator Failure Troubleshooting

What safety rules apply before you touch anything?

Generators produce carbon monoxide, which cannot be seen or smelled and can kill quickly. Run a portable generator only outdoors, well away from windows, doors and vents, and never in a garage, basement or barn attached to living space. Keep a working carbon monoxide alarm in the home.

Let the engine cool before refueling, and do not refuel a running or hot engine. Store fuel only in approved containers, away from the house and ignition sources. Do not work on a generator in the rain or with wet hands.

• Outdoors only, far from openings
• Carbon monoxide alarms in the house
• Cool the engine before refueling
• Dry hands, dry ground

What are the most common reasons a generator will not start?

Many failures come from simple problems: no fuel, old or stale fuel, a closed fuel valve, a switch left in the wrong position, low oil triggering a safety shutoff, a loose or dirty spark plug, a clogged air filter or a weak battery on electric-start models.

Your owner's manual lists what to check for your model, in the order the manufacturer recommends. Follow it instead of guesses from the internet. If you do not have the manual, the maker's website often offers a free copy.

Another common problem is a worn or fouled spark plug, or a unit that has not been used since last season. Using fresh fuel and a clean filter often solves it.

What should you check first?

Work through the manual's checklist calmly. Confirm there is fresh fuel, the fuel valve is on, the choke and switches are set correctly and the oil level is right. Check that the breaker on the generator has not tripped. Look at the air filter and the area around the engine for debris.

Do not take apart fuel systems or electrical components unless you are qualified. If the generator starts but powers nothing, a tripped breaker or a bad connection may be to blame. An electrician can tell you.

• Fuel quality and level
• Fuel valve and switches
• Oil level
• Air filter
• Breakers and connections

Why do generators fail when you need them most?

Most generators sit unused for months, and fuel left in them goes stale and gums up the carburetor. Batteries run down, rodents chew wires, and nobody remembers how to start it. Failures in an emergency are usually maintenance failures, not bad luck.

Run the unit regularly under a light load, follow the maker's schedule for oil and filters, and ask a service dealer or electrician how to store fuel and prepare the machine between uses.

Write the maintenance date on a tag on the unit so you can see at a glance when it was last checked.

When should you call a professional?

If the generator will not start after basic checks, runs roughly, smokes badly, surges or trips breakers repeatedly, stop and call a qualified small-engine repair shop or the maker's service line. For anything involving a transfer switch, house wiring or standby units, call a licensed electrician.

During a widespread outage, repair shops are busy, so ask for an estimate and a time. Avoid unsafe shortcuts, like back-feeding power into a wall outlet, which can injure utility workers.

What do you do while it is broken?

Return to your outage plan: stay warm or cool, keep food closed up, and use stored water. Check on neighbors, and if someone depends on powered medical equipment or you feel unsafe, call 911 or go to a safe place such as a relative's home or a shelter.

Never heat the house with a charcoal grill, a gas range or an engine run indoors. These cause deadly carbon monoxide poisoning.

If you must leave the house, tell someone where you are going and take medications and important papers with you.

• Use your blankets and gather in one room
• Keep fridge doors closed
• Call 911 for medical emergencies
• Go elsewhere if the house is unsafe

How do you make sure it works next time?

Create a simple maintenance routine. Test the generator on a schedule, keep records, replace filters and plugs as the manual says and store extra fuel safely. Keep the manual, spare parts and a list of repair contacts together.

Decide in advance what the generator will power, and think about whether a smaller set of essentials, such as a pump, a heater fan and a freezer, is a better plan than the whole house.

• Test on a schedule
• Keep a maintenance log
• Keep the manual and spare parts together
• List the essentials you must power

Last reviewed: November 12, 2026. Written by the Rural Farm Life Editorial Team. See our editorial policy.