Should you store your lawnmower with gas in it?

Quick Answer

The quick answer is no, you should not store your lawnmower with gas in it. Gasoline can deteriorate and clog carburetors when left for extended periods of time. It’s best to empty the gas tank before storing your lawnmower.

Overview

Lawnmowers require gasoline to operate their engines. This allows you to mow your lawn without needing to be plugged into an electrical outlet. However, gasoline has a relatively short shelf life and can start to degrade within 30 days. This can lead to a number of problems if you store your lawnmower with gas still in the tank.

In this article, we will discuss the risks of storing a lawnmower with gasoline, signs of degraded gasoline, how to properly prepare your lawnmower for storage, and tips for using up gas before storing your equipment. Following proper storage procedures can extend the life of your lawnmower and prevent issues when starting it up again after storage.

Risks of Storing with Gasoline

There are a few key risks that come with storing your lawnmower with gasoline still in the tank:

Gasoline Deterioration

Even when sealed in the gas tank, gasoline will start to deteriorate and oxidize over time. This causes the formation of gums and varnishes that can clog up carburetors and fuel lines. Storage beyond 30 days greatly increases the rate of fuel deterioration. This can make it challenging to start the engine when you go to use the lawnmower again.

Internal Rusting

Some low-quality fuels contain alcohol which can attract moisture inside the gas tank. This moisture promotes rusting of internal engine components when the lawnmower sits unused. Rust can jam up carburetors and damage cylinders or pistons.

Fuel Leaks and Fire Hazard

As gasoline deteriorates, it becomes more volatile. This means older gas is more likely to leak from the fuel system. Leaked gasoline poses a major fire hazard, especially if stored in a garage or shed. Fires started by leaking fuel can result in loss of property or bodily harm.

Difficult Starting

When you go to start your lawnmower after storage, degraded gasoline makes it very hard to start the engine. You may need to make repeated starting attempts flooding the engine with fresh gasoline to get it going again. This puts extra wear on the starter motor and battery.

Damage to Fuel System

The gums and residues left behind by deteriorating gasoline can jam up fuel filters, carburetors, and injectors. This may require a complete disassembly and cleaning of the fuel system to remove blockages. Parts like the carburetor may need replacement if too badly clogged.

Signs of Bad Gasoline in a Stored Lawnmower

Here are some signs that the gas in your stored lawnmower has gone bad:

– Difficulty starting – Requires repeated pulls on the starter cord

– Sputtering, stalling engine – As contaminated fuel is used

– Reduced engine power – Lack of fuel flow due to clogs

– Fuel leaks – Seals and hoses degraded by poor fuel

– Fuel varnish buildup – Residues around cap or carburetor

– Abnormal fuel smell – Strong, pungent odor

– High evaporation – Tank empties quicker than usual

– Engine smoking – Excess deposits burning off

If you encounter any of these issues after long-term lawnmower storage, bad gasoline is likely the culprit. Safely drain the old gas and refill with fresh fuel. The engine should return to normal operation.

How to Prepare a Lawnmower for Storage

Here is a step-by-step guide to properly preparing your lawnmower for storage:

Step 1 – Run Engine until Out of Fuel

Ideally, you should run the lawnmower engine until all gasoline in the tank and system is used up. This may take 20-30 minutes of running time. The engine will sputter and stall once all fuel is consumed.

Step 2 – Drain Remaining Fuel

If unable to run tank dry, siphon or drain remaining gasoline from the fuel tank. Use a hand pump, turkey baster, or open fuel line to remove excess gas. Drain fuel into approved gas containers.

Step 3 – Change Oil

Change the engine oil and filter prior to off-season storage. This removes contaminants and provides fresh oil for start-up. Dispose of old oil at a recycling center.

Step 4 – Remove Spark Plug

Remove the spark plug and pour about an ounce of fresh motor oil into the cylinder hole. Reinstall plug and pull start or rotate engine to coat cylinder internals. This prevents rusting.

Step 5 – Clean Mower

Wipe down the mower deck and other exterior parts. Remove all grass clippings, debris, and dirt buildup. Touch up any chipped paint or rust spots.

Step 6 – Fuel Stabilizer

If unable to run tank dry, add fuel stabilizer to the gas remaining in the tank. Stabilizer enzymes prevent oxidation during storage. Run the engine 5 minutes after adding to circulate.

Step 7 – Battery Removal

Remove any lead-acid starting battery from the mower. Batteries self-discharge over time and can leak or corrode. Store battery indoors on a trickle charger.

Step 8 – Storage Space

Store mower in a clean, dry space away from rain, sun, dirt, and moisture. Avoid temperature extremes. Ideal storage is a garage or shed. Use a cover.

Tips for Consuming Gasoline Before Storage

It’s not always convenient to run a full mower tank dry prior to storage. Here are some tips to use up gasoline supplies:

– Mow lawn areas multiple times to burn remaining fuel

– Empty tank when getting low rather than completely refilling

– Add stabilizer to extend life of partial tanks

– Use an additive to treat entire fuel can if partly filled

– Avoid overfilling tank before last mow of the season

– Run mower engine at high throttle to burn gas faster

– Allow mower to run stationary until stalling from lack of fuel

– Drain gas into vehicle tank if safe and legal in your region

– Give excess gas to someone with equipment needing fuel

The objective is to get unused gasoline out of the mower and consumed in small engines designed for continuous use. Prior planning prevents problems down the road.

Removing Old Gasoline from a Stored Lawnmower

If your lawnmower already has degraded gasoline from previous improper storage, here is how to remove it:

Step 1 – Drain Tank & Carburetor Bowl

Begin by safely draining all old gasoline from the mower’s tank and carburetor bowl into an approved fuel container. The fuel should have a strong odor.

Step 2 – Remove Fuel Filter

Take out any inline fuel filters that connect to the tank. Drain filter housing of accumulated fuel. Replace filter or clean thoroughly if reusable.

Step 3 – Disconnect Fuel Line

Disconnect the fuel line running from the tank to the carburetor. Drain any excess gas from the line. Prepare to remove carburetor.

Step 4 – Remove Carburetor

Take carburetor off mower and disassemble to reveal internal components. Gasket surfaces should be cleaned. Note position of parts for reassembly.

Step 5 – Clean Carburetor

Spray carburetor bores, jets, and openings with carburetor cleaner. Let soak 5 minutes. Flush with clean spray to remove deposits. Dry components fully.

Step 6 – Reinstall Carburetor

Reinstall carburetor using new gaskets or seals. Reconnect fuel line and replace filter if needed. Double check all connections are tight.

Step 7 – Add Fresh Gasoline

Fill tank with fresh 87+ octane gasoline. Add fuel stabilizer if not using quickly. Attempt starting engine. May require repeated cycles to purge excess deposits.

Proper cleaning should allow the mower to run like new again. Always consume or remove gasoline prior to future storage periods.

Warning Signs of Bad Gasoline in Other Small Engines

Lawnmowers are not the only small engine equipment at risk from deteriorating gasoline during storage. Here are warning signs in other devices:

Portable Generators

– Failure to start with repeated pulls

– Runs rough or lacks power

– Produces dark exhaust smoke

– Gas leaks around fuel valve or lines

Snow Blowers

– Whining starter without ignition

– Sputtering, stalling engine

– Loss of power under load

– Foul gasoline odor from tank

Chainsaws

– Hard starting requiring choke

– Cutting out during use

– Poor, uneven idling

– Gummy deposits on fuel cap

String Trimmers

– Worn starter cord due to hard pulls

– Bogging down under load

– High idle speed with throttle off

– Fuel draining quickly from tank

Outboard Boat Motors

– Smoke and hesitation upon starting

– Misfiring at high speeds

– Blackened spark plug electrodes

– Gummed up fuel filters after use

Address deteriorated gasoline as soon as symptoms appear in your small engines. Drain tanks, clean components, and replace with fresh fuel.

Conclusion

Storing a lawnmower with gasoline left in the tank is an invitation for problems down the road. The relatively short shelf life of gasoline, combined with internal rust and residue buildup from decomposition, can lead to frustrating engine issues.

Always run mower tanks dry or drain remaining fuel prior to off-season storage. Taking proper preventative steps will ensure your lawnmower starts and runs cleanly when you need it again. Following the preparation checklist and fuel consumption tips will extend equipment life.

If previous improper storage has led to degraded gasoline in your lawnmower, thoroughly flush the tank, fuel system, and carburetor. Replace deteriorated parts and filters as necessary. While an involved process, proper cleaning will get your engine running smoothly again.

Knowing the risks of bad gasoline as well as prevention and resolution steps will serve you well for all your small engine equipment. Feel free to reach out with any other lawn and garden storage questions!