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Lawnmower Won’t Start? Do this.

deposits and varnish in carburetor bowl

Lawnmower Won’t Start? Do this.

A lawnmower that won’t start, especially when taken from storage, is almost always due to one problem: bad gas.

Storing a lawnmower in the fall without adding gasoline stabilizer to the fuel tank can cause the fuel to break down and plug the fuel passages. If fixing that problem doesn’t help, there are a few other common maintenance practices to try, as we explain below.

Here’s what to do when your lawnmower won’t start

Replace the gas

Over time (like the six months your lawnmower sat in your garage over the winter), the lighter hydrocarbons in gas can evaporate. This process creates gums and varnish that dirty the carburetor, plug fuel passages and prevent gas from flowing into the combustion chamber.

The carburetor bowl below formed corrosion and deposits during storage, which can easily plug fuel passages and prevent the engine from starting.

Deposits and residue in carburetor bowl

Deposits and residue in carburetor bowl

Ethanol-containing gas can absorb water from the atmosphere, which can lead to phase separation, which occurs when ethanol and gas separate, much like oil and water. Ethanol that has absorbed enough moisture and has sat long enough can foul the fuel system and prevent the engine from starting.

No matter how many times you yank the starter cord and pollute the air with your advanced vocabulary, the lawnmower won’t start if it isn’t getting gas.

In extreme cases, evaporation of lighter hydrocarbons can change the gasoline’s composition enough to prevent it from igniting. The gas may be fueling the engine, but it doesn’t matter if it won’t ignite.

If you neglected to add gasoline stabilizer to the fuel prior to storage, empty the tank and replace with fresh gas. If the tank is nearly empty, simply topping off with fresh gas is often enough to get it started.

On some mowers, you can easily remove and empty the fuel tank. Sometimes that’s more trouble than it’s worth. In these cases, use a fluid extraction pump or even a turkey baster. (We keep them in the Sioux Falls location also)

Clean the carburetor

You’ve replaced the fuel, but your lawnmower still won’t start.

Next, try cleaning the carburetor. Remove the air filter and spray carburetor cleaner into the intake. Let it sit for several minutes to help loosen and dissolve varnish and gums.

On some carburetors, you can easily remove the float bowl. If equipped, first remove the small drain plug and drain the gas from the bowl. Remove the float bowl cover and spray the float and narrow fuel passages with carburetor cleaner.

This kind of “quick-and-dirty” carburetor cleaning is usually all it takes to get the gas flowing again and your lawnmower back to cutting grass.

If not, consider removing the carburetor from the engine, disassembling it and giving it a good cleaning. Be forewarned, however: taking apart a carburetor can lead to nothing but frustration for the uninitiated. Take pictures with your phone to aid in reassembly. Note the positions of any linkages or the settings of any mixture screws, if equipped.

If you’re at all reluctant, visit the servicing dealer instead. Also consider replacing the carburetor altogether. It’s a fairly simple process on most smaller mowers and it’s often less expensive than taking it to the dealer.

Clean/replace the air filter

With the air filter removed, now’s the perfect time to clean it. Tap rigid filters on a workbench or the palm of your hand to dislodge grass clippings, leaves and other debris. Direct compressed air from the inside of the filter out to avoid lodging debris deeper into the media.

Use soap and water to wash foam filters. If it’s been a few years, simply replace the filter; they’re inexpensive and mark the only line of defense against wear-causing debris entering your engine and wearing the cylinder and piston rings.

Check the spark plug

A dirty or bad spark plug may also be to blame. Remove the plug and inspect condition. A spark plug in a properly running four-stroke engine should last for years and never appear oily or burned. If so, replace it.

Use a spark-plug tester to check for spark. If you don’t have one, clip the spark-plug boot onto the plug, hold the plug against the metal cylinder head and slowly pull the starter cord. You should see a strong, blue spark. It helps to test the plug in a darkened garage. Replace the plug if you don’t see a spark or it appears weak.

While you’re at it, check the spark-plug gap and set it to the factory specifications noted in the lawnmower owner’s manual.

If you know the plug is good, but you still don’t have spark, the coil likely has failed and requires replacement.

Did you hit a rock or other obstacle?

We’ve all killed a lawnmower engine after hitting a rock or big tree root.

If your lawnmower won’t start in this scenario, you probably sheared the flywheel key. It’s a tiny piece of metal that aligns the flywheel correctly to set the proper engine timing. Hitting an immovable obstacle can immediately stop the mower blade (and crankshaft) while the flywheel keeps spinning, shearing the key.

In this case, the engine timing is off and the mower won’t start until you pull the flywheel and replace the key. It’s an easy enough job IF you have a set of gear pullers lying around the garage. If not, rent a set from a parts store (or buy one…there’s never a bad reason to buy a new tool) or visit the dealer.

My lawnmower starts, but runs poorly

If you finally get the lawnmower started, but it runs like a three-legged dog, try cleaning the carburetor with AMSOIL Power Foam. It’s a potent cleaning agent designed to remove performance-robbing carbon, varnish and other gunk from carburetors and engines.

Power Foam®

Buy AMSOIL Power Foam

Add gasoline stabilizer to avoid most of these problems

Which sounds better? Completing all these steps each year when your lawnmower won’t start? Or pouring a little gasoline stabilizer into your fuel tank?

Simply using a good gasoline stabilizer can help avoid most of the problems with a lawnmower that won’t start. AMSOIL Gasoline Stabilizer, for example, keeps fuel fresh up to 12 months. It helps prevent the lighter hydrocarbons from evaporating to reduce gum and varnish and keep the fuel flowing. It also contains corrosion inhibitors for additional protection.

Gasoline Stabilizer

Buy AMSOIL Gasoline Stabilizer

I have a five-gallon gas can in my garage from which I fuel two lawnmowers, two chainsaws, two snowblowers, a string trimmer, an ATV and the occasional brush fire. I treat the fuel with Gasoline Stabilizer every time I fill it so I never have to worry about the gas going bad and causing problems.

You can also use AMSOIL Quickshot. It’s designed primarily to clean carburetors and combustion chambers while addressing problems with ethanol. But it also provides short-term gasoline stabilization of up to six months.

Weed Eater Won’t Start? Try This

two cycle starting help

We’ve all been there – Weed Eater Starting Foes!

No matter what you call it – weed eater, weed whacker, string trimmer – chances are at some point it won’t start. Few things are more annoying than destroying your shoulder trying to start the weed eater when there’s work to do.

Fortunately, gasoline weed-eater engines are pretty simple, so most DIYers with a few tools and some basic know-how can get a stubborn trimmer running.

Here are our guidelines for troubleshooting a weed eater that won’t start

1) Check the gasoline

Gasoline can break down in as little as 30 days, especially today’s ethanol-containing gas. Homeowners sometimes stash their string trimmer in the garage at season’s end without stabilizing the gas. Oxygen has all winter to break down and ruin the gasoline, leaving you with a trimmer that won’t start in the spring.

If your trimmer falls into this category, empty the old gas from the fuel tank and replace it with fresh fuel.

2) Clean the carburetor

Once gas breaks down, varnish, gums and other debris can form inside the carburetor and clog the tiny fuel passages. This prevents fuel from reaching the combustion chamber and igniting.

Remove the air filter and spray carburetor cleaner into the intake. Let it sit for several minutes to help loosen and dissolve varnish. Replace the filter and try starting the trimmer.

If this doesn’t solve the problem, consider disassembling the carburetor to give it a more thorough cleaning.

Beware, however – taking apart a carburetor marks a point-of-no-return, of sorts. Understanding how the delicate gaskets, tiny screws and needle valves go back together can be a challenge, even on a relatively simple string-trimmer carburetor. Take pictures with your phone throughout the process to help reassembly. Clean all the openings and passages with carburetor cleaner.

If you’re reluctant to take apart the carb, visit the servicing dealer.

3) Clean or replace the spark plug

Oil deposits and carbon can foul the spark plug in a two-stroke engine if a low-quality oil is used. Deposits on the electrode prevent the plug from firing properly, which can reduce performance or prevent the engine from running altogether.

Plugs are inexpensive, so replace it if it’s fouled. If you don’t have a new plug available, clean the deposits from the electrode with light-duty sandpaper and check the gap. Consult the owner’s manual for the correct gap size.

If you know the spark plug is good, but the engine still doesn’t produce spark, the coil is likely to blame and requires replacement.

4) Clean or replace the air filter

A clogged air filter prevents the engine from receiving sufficient air to operate properly.

Before removing the air filter, brush away loose debris from around the filter cover and filter element. Tap rigid filters on a tabletop or the palm of your hand to dislodge any dirt or debris. Compressed air also works well. Make sure you direct air through the filter from the inside to avoid lodging debris deeper in the filter.

Avoid washing paper filters as this can collapse their micro-fine structure. Foam filters, however, can easily be washed using mild detergent and warm water.

As with the spark plug, however, replacement is often the best practice, especially if the filter is excessively dirty.

5) Clean the spark-arrestor screen

On many trimmers, a small screen covers the exhaust outlet and prevents sparks from exiting the muffler and potentially starting a fire.

As with plug fouling, too much oil in the gasoline, inferior oil and continued low-rpm operation can plug the screen with carbon deposits. This prevents exhaust-gas flow, which leads to power loss. In extreme cases, heavy deposits choke airflow enough to leave you with a weed eater that won’t start.

To fix the problem, remove the spark arrestor screen and spray it with a heavy-duty cleaner, like AMSOIL Power Foam®, to soften the deposits before cleaning the screen with an abrasive pad. Reinstall the screen and test the trimmer.

Replace the screen altogether if it’s excessively plugged with carbon.

6) Switch to a better two-stroke oil

Low-quality oil that leads to heavy carbon is often to blame for most of the problems on this list.

Using a good two-stroke oil that burns cleanly and helps prevent carbon deposits is one of the easiest maintenance practices you can perform to ensure your trimmer starts easily, runs well and last for years.

Buy SABER Professional

AMSOIL SABER Professional Synthetic 2-Stroke Oil withstands high heat to fight carbon in gasoline string trimmers and other two-stroke equipment. It’s tested and proven at any mix ratio up to 100:1, offering the convenience of one mix ratio for all your equipment. Plus, it’s formulated with gasoline stabilizer to help keep fuel fresh during short-term storage.

The images here show AMSOIL SABER Professional’s superior cleanliness properties. It’s just one reason professional landscapers, like Duluth Lawn Care, only trust AMSOIL products.

2-cycle mix ratios

AMSOIL SABER Professional mixed at 100:1 delivers better protection against power-robbing deposits than other oils mixed at 50:1.

View the complete test results here.

Follow the guidelines on this list to get your string trimmer back up and running…and to give your shoulder a break.

Which Small-Engine Oil Would You Choose?

small engine cleanliness

Which Small-Engine Oil Would You Choose?

Spring marks the time to store your snowblower and prepare your lawnmower, pressure washer, generator and other equipment for another season.

Make sure to change oil before storing equipment. Used oil contains acidic byproducts that can damage the engine if allowed to sit for months.

If you neglected to change oil in your lawnmower or other equipment prior to fall storage, now is a great time to do that.

Use a high-quality small-engine oil, not simply an inexpensive automotive oil

While easy to assume small equals simple when it comes to engines, the opposite is often true.

Compared to liquid-cooled automotive engines, air-cooled small engines run hotter; operate under constant load; generate more contaminants (with many not using a filter); and are exposed to mud, dirt and rain. Plus, they’re often overlooked when it comes to maintenance.

Most small-engine oils, however, are just re-labeled automotive oils, which are formulated with fuel economy in mind, not engine durability.

AMSOIL Synthetic Small-Engine Oil, in contrast, isn’t merely a re-labeled automotive oil – it’s designed specifically for the unique demands of small engines. It contains a heavy dose of zinc anti-wear additives to protect against wear for maximum power and engine life. It also contains potent detergency additives to fight harmful deposits.

Look at the bottom image of the valve-guide area in a Honda* 5-hp engine tested in the AMSOIL mechanical lab. A competitor’s oil resulted in heavy deposits that caused the valve to stick. In fact, the technician who tore down the engine couldn’t remove the valve due to excessive deposits. Had this engine been in the field, it would have been a matter of time before it failed, leading to a costly repair or replacement. AMSOIL 10W-30 Synthetic Small-Engine Oil, in contrast, minimized deposits and kept the engine running strong.

Small Engine 10W-40 is another product.

This season, make sure your fleet of small-engine-powered equipment is protected – choose AMSOIL.

“Easier starts in cold weather and the ultimate in protection at any temperature. Zero wear on my small engines and most are over 10 yrs old.”

Bobby
Savannah, Ga.

BUY NOW

*All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use. All products advertised here are developed by AMSOIL for use in the applications shown.

How to Fight Ethanol Problems in Small Engines

Phase separation

How to Fight Ethanol Problems in Small Engines

 

In 2005, Congress instituted a new renewable fuel standard that you didn’t get to vote on. In response, refiners made a wholesale switch, removing methyl tertiary butyl ether (MTBE) and blending fuel with ethanol. Ethanol helps reduce petroleum use and greenhouse gas (GHG) emissions, well in special engines made for ethanol only – but you’re not suppose to know that..  (even though you end up using more fuel to make up for the losses). Derived from corn (Round-up ready which destroys our health), ethanol supports U.S. agriculture (as long as they don’t ask questions and buy the seed they are forced to) and helps support energy independence. (as if allowing private railways wouldn’t but competing with AMTRAK is against the law currently).

Ethanol, however, can cause a number of problems, particularly in small engines. These problems center on the two following issues:

1) Dissolving plastics and creating deposits

Ethanol is an excellent solvent and drying agent that dissolves old gum and varnish deposits from the gas tank and fuel lines. However, it can also dissolve plastic and create deposits. Honda states that the dissolved material can clog filters or pass through and leave deposits on fuel injectors, fuel pumps, fuel-pressure regulators, carburetor jets, intake tracts, valves and valve guides.

Small-engine manufacturer ECHO agrees, stating in its warranty that these deposits can lead to poor engine performance; loss of power; overheating; fuel vapor lock; improper clutch engagement caused by increased engine idle speeds, which allows cutting attachments to turn while the unit is idling; and premature deterioration of fuel lines, gaskets, carburetors and other engine components.

2) Ethanol and water don’t mix

Small engine manufactures have spent considerable time studying the relationship between ethanol and water.

The white flaky deposits in this carburetor are attributed to ethanol.

ECHO warns that ethanol will absorb a small amount of moisture and stay in suspension within the gasoline for a while. However, the ethanol will only absorb up to ¾ of an ounce of water in a gallon of gas before it reaches its saturation point. Once the ethanol has absorbed enough moisture to reach its saturation point, phase separation occurs. Phase separation means the ethanol and absorbed water drop to the bottom of the fuel container since it is heavier than the gas and oil, leaving the gasoline and oil mix to float on top of the tank. Most operators never notice water in the can when they refuel their equipment. The end result is often a carburetor ruined with rust and corrosion. These expensive repairs can cost more than $75 and are not typically covered by warranty.

Stihl stresses that the layer of gasoline left floating on top has a lower octane level than the original ethanol-gasoline blend, which can result in unstable engine operation, power loss and major engine failures.

Ethanol’s affinity for water explains why so many ethanol-related problems surface in the marine industry. In fact, some marina personnel say up to 65 percent of their service orders are attributable to fuel-system problems.

Combating ethanol problems

Although some fuel additives on the market claim to reverse the effects of phase separation, there’s no way to reintegrate gasoline and ethanol once they’ve separated. Instead, it’s best to prevent it.

One solution is to use non-oxygenated, ethanol-free gas in your small engines. It costs a little more, but it eliminates problems
associated with ethanol. Another solution is to treat every tank of fuel and container of gas with AMSOIL Quickshot. It helps keep water molecules dispersed in the fuel to prevent phase separation. It also cleans varnish, gums and insoluble debris while stabilizing fuel during short-term storage.

Quickshot was tested in fuel containing 10 percent ethanol. Controlled plugging of injectors showed a 70 percent flow improvement, while oxidation stability improved 44 percent over untreated fuel.

Regardless whether you’re pro- or anti-ethanol, we can all agree on the importance of taking care of our small engines.