How Do you Prep Generator Fuel Before a Hurricane or Winter Storm?

The forecast cone swings toward your county on a Tuesday. By Thursday the gas station lines wrap around the block, the hardware store is out of fuel cans, and the generator in the garage hasn't run since last fall.

For an approaching hurricane, five to seven days before expected landfall is a good time to inspect the fuel you already have, replace questionable or contaminated gasoline, buy and treat fresh fuel, check the generator's fuel system, and run the generator under load. For winter storms, do the same preparation before the season and recheck the generator when severe weather enters the forecast.

Don't assume stored gasoline is bad simply because it is more than 30 days old. Look for water, phase separation, sediment, or other signs of contamination, consider how long and under what conditions it has been stored, and—most importantly—make sure the generator starts and carries load while you still have time to correct a problem.

That's when many people discover whether their generator and its fuel survived the off-season.

A generator that won't start, surges, or dies under load may have a mechanical problem. But gasoline that has degraded during storage, water contamination, deposits in the carburetor, or debris in the fuel system can produce many of the same symptoms.

Hurricane and winter-storm generator preparation follow much of the same basic routine: inspect what you have, replace questionable fuel, fill your approved fuel containers with fresh treated gasoline, inspect the generator, and test it under load.

The important part is doing those things before the storm creates a second problem: finding the fuel, parts, or supplies you suddenly need.

When should you start prepping generator fuel for a storm?

For an approaching hurricane, start five to seven days before expected landfall. For winter weather, the better strategy is to prepare the generator in late fall and then recheck it when a significant storm enters the forecast.

That gives you time to inspect old fuel, buy fresh gasoline before demand spikes, correct problems in the tank or fuel system, and run the generator under load while replacement parts and supplies are still available.

The checklist itself may take only an afternoon. The problem is everything that becomes harder to find as the storm gets closer: gasoline, approved fuel containers, filters, spark plugs, carburetor parts, and sometimes the generator itself.

Commercial emergency-fuel planning follows the same basic principle. Fuel deliveries, fuel testing, and equipment checks happen early because the closer you get to a major weather event, the fewer options you have if something goes wrong.

Winter storms are harder to time. An ice storm or major snow event may become likely only a few days ahead, and nobody wants to discover a fuel-system problem in a freezing garage.

Do the full seasonal preparation before winter. Then treat the storm forecast as a reason to recheck the generator, replenish your fuel supply, and perform another loaded test run.

If the storm is already inside the five-day window, compress the schedule—but don't skip the test run.

A generator that fails today is a maintenance problem.

A generator that fails after the power goes out is an emergency.

Why does generator fuel fail right when the power goes out?

Because the generator may have spent months sitting between the last time it ran and the moment you actually need it.

Gasoline changes during storage. Volatile components can be lost, oxidation can produce gums and deposits, and water can enter through condensation, contaminated fuel, or exposure to moisture. Ethanol-blended gasoline adds another concern because ethanol readily mixes with water.

If enough water accumulates in ethanol-blended gasoline, the ethanol-water mixture can separate from the gasoline and form a distinct lower layer. That's phase separation, and fuel drawn from that layer can cause serious starting and running problems.

The carburetor is particularly vulnerable to storage problems because it contains small passages and, on many generators, a bowl in which gasoline can remain after the engine is shut down. As that fuel evaporates and degrades, deposits can restrict the passages needed to meter fuel correctly.

That is why a fuel problem can look remarkably like a broken generator. The engine may refuse to start, run only with the choke partly closed, surge, or die when a load is applied.

Older generators can have additional problems. Steel tanks can develop rust and sediment, which may eventually reach the filter, screen, carburetor, or fuel line.

Fuel can also find its way into the crankcase under certain failure conditions, diluting the engine oil and reducing its ability to lubricate. If the oil level is unexpectedly high or the oil smells strongly of gasoline, don't run the engine until the cause has been investigated and the contaminated oil has been replaced.

Following the manufacturer's shutdown and storage procedure—including use of the fuel shutoff valve when specified—helps reduce storage-related fuel problems.

How can you tell if your generator fuel is ready for a storm?

You can't prove that gasoline is good just by looking at it, but a visual inspection can identify several reasons not to use it.

Draw a small sample into a clean, clear container and inspect it against a light background. Look for a separate lower layer, haze, suspended material, rust, sediment, or other obvious contamination.

A distinct lower layer in ethanol-blended gasoline can indicate water-related phase separation. That fuel should not simply be treated and put back into service.

Darkened or unusual-looking gasoline may indicate aging or contamination, but appearance alone cannot tell you whether gasoline will perform properly. Likewise, gasoline that looks perfectly clear is not necessarily fresh.

When the history of the fuel is unknown or its condition is questionable, replacing a relatively small amount of portable-generator gasoline with fresh fuel is usually much less expensive than discovering during an outage that the generator will not run reliably.

Then test the generator itself.

Starting is only the first step. Allow the engine to warm and operate the generator under an appropriate electrical load, following the manufacturer's instructions. A partially restricted fuel system may allow an engine to start and idle normally but fail when fuel demand increases.

Watch for surging, hunting, hesitation, or stalling under load. Running better with partial choke can point toward a lean fuel mixture, which may result from restricted carburetor passages or another fuel-delivery problem. Stalling under load can also result from restricted fuel flow, but don't assume every running problem is caused by stale gasoline.

Check the engine oil at the same time. Confirm the correct level and look for anything unusual. If the oil level has risen unexpectedly or the oil smells strongly of gasoline, investigate before running the engine.

The real storm-readiness test is simple:

Will the generator start, warm up, accept load, and continue running normally before the storm arrives?

What should you do to the generator fuel system before landfall?

Start by dealing with questionable fuel.

Remove gasoline that shows phase separation, significant water, sediment, or other obvious contamination. If stored fuel has an uncertain history or has been sitting untreated for an extended period, replacing it with fresh gasoline is inexpensive insurance compared with losing the generator during an outage.

Inspect the tank, fuel lines, filter or inlet screen, and accessible fuel-system components for leaks, deterioration, rust, or contamination. Follow the generator manufacturer's maintenance procedures for anything that requires disassembly.

Fill your approved fuel containers with fresh gasoline and treat the fuel when you buy it if it may remain in storage.

Then run the generator long enough for the fresh treated fuel to reach the fuel system and operate the generator under an appropriate load.

Once testing is complete, shut the generator down according to the manufacturer's instructions and follow its recommended procedure for the fuel valve and storage.

The objective is not merely to have gasoline.

It is to know that the gasoline, fuel system, and generator will work together when the utility power disappears.

How do you clean a portable generator fuel tank?

Work outdoors in a well-ventilated area away from flames, sparks, smoking materials, heaters, electrical equipment, and other ignition sources. Allow the engine to cool completely before working around gasoline.

Before removing the tank or disconnecting fuel lines, consult the owner's manual for your generator. Designs vary considerably, and some tanks are much easier to service than others.

Drain old or contaminated gasoline into an approved container and handle or dispose of it according to local requirements.

Inspect the inside of the tank for water, rust, sediment, and other debris. A badly rusted, leaking, cracked, or otherwise damaged tank should be repaired or replaced according to the manufacturer's recommendations rather than returned to service.

Remove loose contamination using a method appropriate for the tank and generator design. Inspect the fuel filter, sediment cup, inlet screen, and accessible fuel lines and replace components that are damaged, restricted, or heavily contaminated.

Be particularly careful about improvised cleaning methods. Gasoline is extremely flammable, and introducing tools or materials not intended for fuel-system service can create unnecessary hazards.

After reassembly, add fresh fuel, check carefully for leaks, and run the generator according to the manufacturer's procedure. Reinspect the filter or screen afterward if significant contamination was removed from the tank.

What should go in the fresh fuel?

Start with fresh gasoline of the grade and ethanol content approved by the generator manufacturer.

Buy it from a station with good fuel turnover, and if the gasoline will be stored, treat it when you buy it rather than waiting until months later when deterioration may already have occurred.

For ethanol-blended gasoline, Ethanol Defense is designed to help control the problems associated with water and fuel degradation during storage. It uses alcohol-free chemistry for water control rather than adding additional alcohol to the fuel, and its detergent package helps control deposits in the fuel system.

Treatment works best as prevention.

No fuel treatment should be expected to reverse severe gasoline degradation or restore fuel that has already undergone phase separation.

Treat the reserve fuel cans at the same time. Use only approved gasoline containers, store them as required by local fire and safety codes, and rotate the fuel rather than assuming that treatment gives gasoline an unlimited storage life.

How much fuel should you keep?

Start with the generator manufacturer's published fuel-consumption or runtime data at a realistic load. Then estimate how many hours per day you expect to operate the generator and how long you need your reserve to last.

That gives you a much better number than simply buying as many cans as you can find.

How is winter storm generator prep different from hurricane prep?

The basic fuel-system preparation is the same, but winter adds cold-weather starting and operating concerns.

Cold temperatures increase engine-oil viscosity, which can make cranking or pull-starting more difficult. Use the oil viscosity recommended by the generator manufacturer for the temperatures you expect.

Winter also makes advance preparation more important. A generator sitting in an unheated garage or shed is much easier to inspect and test in October or November than during freezing rain in January.

Seasonal gasoline formulations can also differ. Gasoline volatility is adjusted throughout the year and by region to provide appropriate starting and drivability characteristics while controlling evaporative emissions.

That is another reason not to make old hurricane-season gasoline your first choice for a winter emergency. By winter it has already spent months in storage, and fresh locally purchased gasoline will generally be more appropriate for current seasonal conditions.

Hurricane season presents the opposite environmental challenge. Higher storage temperatures generally accelerate chemical reactions involved in gasoline degradation, making good storage practices and early treatment particularly important.

In either season, the basic principle remains the same:

Buy fresh fuel, treat it when appropriate, maintain the generator according to its manual, and test the complete system before you need it.

Winter storms add one critical safety concern. Snow and drifting ice can change the environment around a generator after you set it up. Keep the unit outdoors and well away from the house, and make sure snow does not block the engine's cooling airflow or exhaust.

Never move a running generator into a house, garage, porch, shed, or other enclosed or partially enclosed area because of cold, snow, or rain. Portable generators produce carbon monoxide, an odorless gas that can kill without warning.

Follow current CPSC guidance for generator placement, including operating portable generators outdoors at least 20 feet from the house when possible, with the exhaust directed away from the home and other occupied structures.

How much Ethanol Defense do you need for storm fuel?

Treat at the can, the day you buy the gas. These rates cover the fuel most storm prep involves.