What does a neglected portable generator cost when the power goes out?
Updated August 2026
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The generator bought for the outage refuses to start the night you finally need it, and the culprit is almost always stale fuel gumming up the carburetor: a $50 DIY carb kit, or a $75–250 clean or rebuild at a shop, for a failure that costs nothing to prevent. A generator that sits with old gas in it all year is the classic no-start, and a dead unit through a multi-day outage means a fridge and freezer of spoiled food, no heat, and a dark sump pit. The other cost is deadlier and free to avoid: generator exhaust is loaded with carbon monoxide, which kills people every year who run one too close to the house.
The escalation ladder
Every row below is the same leak, left a little longer. The top is a cheap warning; the bottom is a claim.
| What happens | Typical bill | How fast |
|---|---|---|
| You run it 20 minutes every few months on fresh, stabilized fuel | $0, a recurring reminder | Quarterly |
| You change the oil on schedule and store it dry | $10–20 in oil, DIY | Per the manual |
| Stale fuel gums the carburetor and it will not start | $50 DIY carb kit, or $75–250 at a shop | When you need it most |
| The unit stays dead through a multi-day outage | Spoiled fridge and freezer food, no heat | Days |
| It is run in the garage or right by a window | Fatal carbon monoxide poisoning | Minutes |
Warning signs
You want to find these problems on a calm afternoon, not during a storm. Hard starting, a rough or surging idle, sputtering under load, and a strong varnish smell from the fuel all point to stale gas and a gummed carburetor. Pull the last-run date off your log; if you cannot remember the last time it ran, treat it as suspect. A gummy, lacquered residue in the carburetor bowl and a pull cord that cranks without catching are the physical confirmations. On the safety side, any exhaust smell drifting toward the house while it runs means it is too close, move it out to 20 feet immediately.
The prevention math
Keeping a portable generator ready is cheap and mostly about fuel. Run it for 15–20 minutes every few months, treat the gas with fuel stabilizer or store the unit dry, and change the oil on the schedule in the manual. Do that and you skip the $75–250 carburetor visit and, more to the point, you know it will start. Just as important is where you run it: keep it at least 20 feet from the house with the exhaust pointed away from doors and windows, never in a garage or basement, and buy a model with automatic CO shutoff. A budget unit that needs a costly repair is often not worth fixing. The run interval is in how often to start a portable generator, alongside how long one lasts, the maintenance checklist, and the repair-or-replace call.
Every line in that table starts with a skipped 10-minute task. OnOtto keeps the 10-minute version on your calendar so the $2,000 version never happens.
Get the nudge before the billFrequently asked questions
Why will my generator not start after sitting all year?
Ethanol gas breaks down in a few months and leaves a gummy varnish that clogs the carburetor's tiny jets, so the engine cannot get a clean fuel-air mix and will not fire. That is the number-one reason a stored generator no-starts. Draining the fuel or adding stabilizer before storage prevents it; once it is gummed, you are looking at a $50 DIY carb-cleaning kit or a $75–250 shop job. Running it briefly every few months keeps fresh fuel moving through.
How often should I run a portable generator?
Start and run it under a small load for 15–20 minutes every one to three months. That circulates fresh, stabilized fuel, keeps the carburetor clear, charges the electric-start battery if it has one, and confirms it actually works before you are depending on it. Pair each run with a quick check of the oil level. See how often to start a portable generator for the full routine and off-season storage steps.
How far from the house should a generator run?
At least 20 feet away, on a dry surface, with the exhaust aimed away from any door, window, or vent. Never run one in a garage, breezeway, basement, or crawl space, even with the door open, because carbon monoxide pools fast and is deadly. Choose a model with a built-in CO sensor that shuts it off automatically, and make sure the home has working CO alarms. Generator exhaust kills people every year, and every one of those deaths was preventable.
Is it worth repairing an old portable generator?
It depends on the unit and the fault. A carburetor clean or rebuild at $75–250 is worth it on almost any generator. A major repair, like a new engine or a burned-out alternator, often costs more than a comparable new unit on an inexpensive $400–800 model, so replacement wins. On a larger, higher-quality generator the math flips toward repair. Our repair-or-replace guide for portable generators lays out the thresholds.