Can Old Gas Cause a Lawn Mower Not to Start? How to Fix

It is not easy to imagine that gasoline can go bad, but the truth is, gas disintegrates overtime and becomes unsuitable to use in a machinery including lawn mowers. Bad gas can damage your lawn mower engine or result to a reduced performance. So, can old gas cause a lawn mower not to start?

Yes, old gas can cause your lawn mower not to start especially after a winter storage. Gasoline can go bad in as little as 3 to 4 weeks, the reason why you should empty the gas tank or add fuel stabilizer when storing your lawn mower for longer.

Can Old Gas Cause a lawn Mower Not to Start

Overtime, gas is likely to lose its combustible properties and volatile compounds as a result of oxidation and evaporation. Gasoline that’s gone bad, can damage internal components of the engine. It may start to form a gum residue that could cause blockages in the carburetor and fuel lines.

Too old ethanol-gasoline blends may draw water vapor into your fuel line or gas tank, which could result to internal corrosion. The water droplets may also mix with the gas in the tank which automatically reduce its combustibility. This may prevent your lawn mower from starting at all.

If you are lucky to start your mower with bad fuel, you are likely to run into other problems. Your lawn mower may not run as smoothly and in some cases may sputter or die during operation. This can be one mistake that will cost you expensive repairs or total loss of your engine.

How to Fix Bad Gas in your Lawn Mower

If your lawn mower won’t start after sitting or die during operation as a result of bad gas, then you have to do a number of things to bring your engine back to life:

  1. Start by removing all the sediment and residue build-up in the tank. Refer to owner’s manual for service procedures and information on how to remove the build-up from the fuel tank.
  2. Drain all the bad gas from the fuel tank. Run a siphon hose from the gas tank to a container and pump the bulb to pull out gas from the fuel tank.
  3. Disassemble the carburetor and clean it to remove any sediments and residue buildup.
  4. If there are any blocked fuel line, you may need to replace them. This may require the help of an expert or an authorized dealer.
  5. Assemble back everything and add new fuel to the fuel tank and try to start your lawn mower.

If your lawn mower is not starting after the restoration, check if the spark plug is in good condition and its cable is well connected. You may also need to clean the spark plug or replace if worn out or damaged. A riding lawn mower may also not start when the battery is flat, try to jumpstart your lawn mower or replace the battery.

How to Prevent Lawn Mower Old Gas Problems

In most cases, lawn mower fuel will go bad during the long winter storage. However, this can be prevented if you properly winterize your lawn mower before storage. There are two ways you can use to deal with any remaining fuel in your lawn mower prior to a winter storage:

Removing all the remaining fuel

Emptying the lawn mower fuel tank is one of the easiest ways of preventing bad fuel problem when spring comes. You can decide to run your lawn mower engine until all the gasoline is combusted or drain all the remaining gas from your lawn mower tank using a siphon pump.

To ensure that no fuel is remaining in the system after the draining, start the lawn mower and let the engine run until it stops due to lack of fuel. However, experts discourage against emptying a mower’s tank as it can still lead to moisture condensing in the fuel tank during the winter storage.

Add storage-grade fuel stabilizer

Adding a specialized storage-grade fuel stabilizer into your lawn mower is an effective way of dealing with bad fuel problems. A stabilizer can keep gasoline fresh for more than one year without need to drain the fuel tank. The product works by slowing down the fuel oxidation process or by breaking down any forming water into dispersed droplets.

To use this method, begin by draining all the fuel from the tank. This will let you know exactly how much fuel you should add as prescribed on the fuel stabilizer label. Next, choose a storage-grade fuel stabilizer recommended for your lawn mower type and add the recommended amount into the empty fuel tank.

Now add new fuel to top the tank to 95% so that you can avoid fuel spills. Run the lawn mower engine for 10 minutes so that the stabilized fuel can move through the entire engine and carburetor. Finally, stop your lawn mower engine, let it cool down and store your lawn mower in a clean dry place.

What to do With Old Gas

Now that you have siphoned the bad gas from your lawn mower fuel tank, what do you do with it? New York State Department of Environmental Conservation explain that, old gasoline can be reconditioned and used in trucks, cars, lawn mowers and other engines.

However, this will depend on how old or contaminated gasoline is and probably what your owner manual recommends on use of reconditioned oil in your engine. Gasoline contaminated with other engine fluids such as oil, brake fluid, transmission fluid or antifreeze should not be reconditioned or reused, it should be disposed.

Gasoline is highly toxic and flammable therefor should not be poured into storm drains, into septic systems, or on the ground. It should also not be disposed with other regular household garbage or recycling. Disposal of gasoline should be done through your local household hazardous waste program.

Final Thought

Without proper storage preparation of your lawn mower, fuel can go bad within a short period of time. Bad fuel not only give you hard time to start your lawn mower but can also damage your engine. Always stabilize the fuel when storing your lawn mower for winter to have an easy start when the mowing season comes.

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