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Should you drain gas from a generator before storage?
For long-term storage, draining gasoline may be recommended—but the correct procedure depends on the generator model, fuel system, storage period, and manufacturer instructions.
Gasoline deteriorates during storage and can contribute to hard starting, fuel-system deposits, moisture-related problems, and carburetor issues. However, not every generator follows the same storage procedure.
For short storage periods, some manufacturers allow fresh gasoline treated with an appropriate fuel stabilizer. For longer storage, the fuel tank and/or carburetor may need to be drained.
DIYPOWER provides portable, diesel, natural gas, standby, prime, and continuous-power generator solutions. This guide explains how fuel type affects generator storage and how to prepare a generator for its next operating period.
Table of Contents
Use the generator manufacturer's storage instructions first.
As a general guide:
Storage Situation | Recommended Action |
|---|---|
Short-Term Storage | Fresh fuel may remain if permitted by the manufacturer |
Several Weeks or Months | Fuel stabilizer or carburetor draining may be recommended |
Long-Term Storage | Fuel-system draining may be required |
Diesel Generator | Focus on fuel quality, water and contamination |
Pipeline Natural Gas Generator | No onboard gasoline tank to drain |
There is no universal storage period that applies to every generator.
For example, Honda provides different procedures for storage periods ranging from 1–2 months, 2–12 months, and more than one year. Generac recommends draining fuel from applicable portable generators when storing them for more than 30 days.
Always follow the instructions for your specific engine and generator.
Gasoline begins to oxidize and deteriorate during storage.
As fuel ages, it can contribute to:
Hard starting
Rough operation
Carburetor deposits
Restricted fuel passages
Fuel-system corrosion
Reduced generator reliability
Gasoline remaining in a carburetor can be particularly vulnerable because only a small quantity is present and it is exposed to engine heat and air.
Honda notes that gasoline can deteriorate during storage and that stale fuel can create sticky deposits capable of clogging small fuel-system passages.
Ethanol-blended gasoline can create another concern.
Ethanol can attract moisture. Under unfavorable storage conditions, water contamination can contribute to corrosion and starting or running problems.
This is why fuel management is an important part of gasoline generator storage.
Instead of applying one rule to every generator, divide storage planning according to the expected downtime.
If the generator will be used again relatively soon, complete fuel removal may not be necessary.
Depending on manufacturer instructions, preparation may include:
Using fresh gasoline
Adding approved fuel stabilizer
Running the engine to circulate treated fuel
Closing the fuel valve
Checking engine oil
Keeping the generator dry
Fuel stabilizer should be added to fresh fuel. It cannot restore gasoline that has already deteriorated.
For longer periods, the manufacturer may recommend draining:
Fuel Tank → Fuel Line → Carburetor
This reduces the amount of aging gasoline left inside the fuel system.
The exact procedure varies by generator.
Do not assume that simply running every generator until it stops is the correct storage method. Follow the storage section of the applicable owner's manual.
The basic process can be kept simple:
1. Check the Owner's Manual
Confirm the manufacturer's recommended storage procedure.
2. Manage the Fuel
Use stabilized fresh fuel or drain the fuel system according to the specified storage period.
3. Check Engine Oil
Replace or service the oil if required by the maintenance schedule.
4. Inspect the Generator
Check filters, cables, battery condition, connections, and visible damage.
5. Clean the Unit
Remove dirt, dust, oil residue, and debris.
6. Store It Correctly
Keep the generator upright in a clean, dry location and follow the manufacturer's ventilation and fuel-storage precautions.
Gasoline is highly flammable. Fuel handling should always be performed away from ignition sources and according to the generator manufacturer's safety instructions.
This depends on the generator.
Some portable-generator manufacturers recommend removing fuel from the tank and carburetor before extended storage.
Others provide different procedures depending on storage duration.
For example, Honda recommends draining the carburetor for some intermediate storage periods and draining both the fuel tank and carburetor for storage longer than one year on certain models.
Therefore:
Do not treat “run it completely dry” as a universal rule for every generator.
Follow the storage procedure specified for the exact model.
Fuel stabilizer can help slow gasoline deterioration during storage.
It is most useful when:
Added to fresh gasoline
Mixed at the correct ratio
Circulated through the fuel system
Used within the stabilizer manufacturer's specified period
Fuel stabilizer does not make old gasoline fresh again.
If gasoline has already deteriorated, adding stabilizer will not reverse the chemical changes that have already occurred.
For this reason, storage preparation should begin with fresh fuel rather than gasoline that has already been sitting for an extended period.
Fuel-storage requirements change significantly depending on the type of generator.
Generator Type | Main Storage Concern | Storage Focus |
|---|---|---|
Gasoline Generator | Fuel deterioration and carburetor deposits | Stabilize or drain according to manufacturer |
Diesel Generator | Water, contamination and long-term fuel quality | Inspect and maintain fuel system |
Natural Gas Generator | Gas supply rather than onboard liquid fuel | Inspect supply and generator systems |
Gasoline requires particular attention during storage because it can deteriorate relatively quickly.
Portable gasoline generators may therefore require:
Fuel stabilizer
Carburetor draining
Tank draining
Periodic exercise
depending on the manufacturer's recommendations.
Diesel generators require a different storage strategy.
Industrial diesel systems are more concerned with:
Water contamination
Sediment
Fuel cleanliness
Storage-tank condition
Fuel filters
Long-term fuel quality
Large standby diesel generators may remain installed and ready for emergency use rather than being physically “stored” between operating periods.
For industrial applications, explore DIYPOWER Diesel Generator Sets.
Pipeline-fed natural gas generators do not normally have an onboard gasoline tank that must be drained before storage.
Instead, maintenance focuses on:
Gas supply
Fuel pressure
Engine condition
Lubrication
Cooling system
Starting battery
Controls
Scheduled exercise
This can eliminate many of the gasoline-storage issues associated with portable carbureted generators.
Explore DIYPOWER Natural Gas Generators for industrial natural gas power applications.
Fuel is only one part of generator storage.
Before leaving equipment unused for an extended period, check:
Follow the correct procedure for gasoline, diesel, or gaseous fuel.
Check oil condition and service interval.
Inspect and clean or replace if required.
For electric-start generators, maintain the starting battery according to manufacturer requirements.
For liquid-cooled industrial generators, inspect coolant level and condition.
Check cables, terminals, and visible connections.
Remove dust, dirt, leaves, oil, and other contamination.
Keep equipment protected from:
Excessive moisture
Corrosive environments
Dirt
Physical damage
For permanently installed industrial generators, scheduled maintenance and periodic testing are usually more relevant than seasonal storage.
A small quantity of gasoline can deteriorate and leave deposits inside small carburetor passages.
Follow the manufacturer's procedure for carburetor storage.
Fuel stabilizer helps preserve fresh fuel.
It does not restore degraded gasoline.
Storage recommendations vary by manufacturer and model.
Use the owner's manual rather than a universal internet rule.
A generator with a well-maintained engine may still fail to start if its battery has discharged during storage.
Moisture can contribute to corrosion of:
Electrical terminals
Metal components
Fuel-system parts
Generator windings
Keep the generator dry and protected.
Some standby-generator systems are designed for periodic exercise.
Follow the manufacturer's recommended exercise and maintenance schedule.
Industrial standby generators are different from portable gasoline generators.
A large standby system may remain installed for years and must be ready to start whenever utility power fails.
The focus is therefore not simply:
“Should I drain the fuel?”
Instead, facility managers should consider:
Fuel Quality + Starting Reliability + Preventive Maintenance + Load Testing + Battery Condition + Cooling + Controls
For diesel standby systems, stored fuel condition becomes important.
For natural gas systems, fuel-supply pressure and availability must be maintained.
For facilities requiring larger standby systems, DIYPOWER provides generator configurations for emergency standby, prime, continuous, and data-center applications.
Fuel-storage maintenance is one reason gasoline and pipeline natural gas systems have very different operating characteristics.
A portable gasoline generator requires an onsite fuel supply that may need:
Stabilization
Rotation
Draining
Refilling
A pipeline-fed natural gas generator does not store gasoline onboard.
However, this does not mean natural gas is maintenance-free.
Natural gas generators still require:
Engine maintenance
Lubrication
Cooling-system inspection
Battery maintenance
Ignition-system service
Control-system testing
For more information, read How Does a Natural Gas Generator Work?.
Portable gasoline generators can be practical for temporary and lower-power applications.
A stationary generator may be more appropriate when a facility requires:
Automatic emergency power
Higher electrical output
Longer operating periods
Industrial loads
Automatic transfer
Remote monitoring
Regular standby operation
DIYPOWER's generator range covers Prime Power, Emergency Standby Power, and Continuous Power applications.
For large natural gas projects, DIYPOWER Natural Gas Power Stations provide another option for industrial power generation.
Before restarting a generator after extended storage:
1. Inspect the Generator
Look for leaks, corrosion, damaged wiring, loose components, or contamination.
2. Check the Fuel
If the system was drained, refill it with the correct fresh fuel.
If fuel remained in storage, confirm its condition according to manufacturer guidance.
3. Check Engine Oil
Verify the correct level and condition.
4. Inspect the Air Filter
Clean or replace if necessary.
5. Check the Battery
Make sure the starting battery is properly charged.
6. Start Without Load
Allow the generator to stabilize according to its operating instructions.
7. Verify Operation
Check voltage, frequency, engine operation, alarms, and controls before applying critical loads.
For industrial standby equipment, follow the manufacturer's commissioning and maintenance procedures.
Usually not.
Whether gasoline should be drained depends on the generator model, expected storage duration, fuel condition, and manufacturer's instructions.
There is no single period that applies to every generator or fuel formulation.
Gasoline begins deteriorating during storage, and environmental conditions can accelerate the process.
Follow the generator manufacturer's fuel-storage guidance.
If the generator will remain unused for an extended period, the manufacturer may recommend draining some or all of the fuel system.
Check the storage procedure for your specific model.
It depends on the expected storage duration and manufacturer instructions.
Fuel stabilizer can help preserve fresh gasoline during certain storage periods, while longer storage may require draining the carburetor or fuel tank.
No.
Fuel stabilizer is intended to help preserve fresh gasoline. It does not restore fuel that has already deteriorated.
Only if the manufacturer's storage procedure recommends doing so.
Do not assume running completely dry is required for every generator.
Industrial diesel-generator storage is different from gasoline-generator storage.
The main concerns include fuel quality, contamination, water, tank condition, and filtration. Follow the engine and generator manufacturer's maintenance requirements.
A pipeline-fed natural gas generator does not normally have an onboard gasoline tank to drain.
However, the generator still requires scheduled engine, fuel-system, battery, cooling, and electrical maintenance.
Some manufacturers permit gasoline to remain during certain storage periods if the correct preparation procedure is followed.
Always check the owner's manual for the specific generator.
Check the fuel, engine oil, battery, air filter, electrical connections, visible leaks, and overall condition before startup.
DIYPOWER provides power-generation equipment for portable, commercial, and industrial applications.
Solutions include:
Selecting the correct generator should consider not only rated power but also fuel availability, operating hours, storage requirements, maintenance, load profile, and installation environment.
So, should you drain gas from a generator before storage?
For a gasoline generator, the answer depends on the generator model and expected storage duration. Shorter storage periods may allow fresh stabilized fuel, while longer storage may require draining the carburetor, fuel tank, or complete fuel system according to manufacturer instructions.
The key principle is:
Do not apply one storage rule to every generator. Follow the manufacturer's procedure for the specific model and fuel system.
Gasoline generators require particular attention to fuel deterioration, while diesel generators focus more on stored-fuel quality and contamination. Pipeline-fed natural gas generators avoid onboard gasoline-storage issues but still require regular preventive maintenance.
DIYPOWER provides portable, diesel, natural gas, standby, prime, and continuous-power generator solutions for different operating environments and power requirements.
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