Lawn Mower Won't Start - Troubleshooting

Failure to perform routine mower maintenance can lead to problems in spring. (Photo by Katie Jacewicz)

Failure to perform routine mower maintenance can lead to problems in spring. (Photo by Katie Jacewicz)

The return of warm weather signals lawns to come out of dormancy and spring into action. But if your lawn mower won't start, you could quickly drown in a knee-high sea of green.

Dan Hale, owner of highly rated Broad Ripple Lawn Equipment in Indianapolis, says most mower problems are the direct result of failure to perform routine lawn mower maintenance at the end of the mowing season.

"People don’t really address the standard maintenance issues that are important to keep a mower running," he says. "It’s a piece of equipment that nobody wants to own for a job nobody wants to do."

Lawn mower maintenance tips

"The biggest problem that people have is leaving old gasoline in the mower," he says. "Over the winter months [gasoline] loses volatility - then, in the spring when they try to start it, they have a problem."

Also, lawn mower repair pros say cold temperatures cause ethanol-based fuel to gel up, which can clog the carburetor and prevent your mower from starting.

To prevent old gas from keeping you from your lawn-cutting duties, completely drain the gasoline at the end of each mowing season, Hale suggests.

One other big reason mowers fail to start in spring: clogged, broken or corroded components. Something as simple as a clogged air filter can compromise the entire mower, Hale says.

"If they don’t clean their air filter, it fills up and the unit runs more inefficiently. Then you get carbon building up on the cylinder and the spark plug to the point it will cause the spark plug to foul and not work," he says.

Prefer to Do It Yourself? How to Tune Up and Maintain a Lawn Mower

For those who don't like getting grease under their fingernails, Hale recommends a professional lawn mower tuneup, which involves replacing the spark plug and air filter, sharpening the mower blades and changing the oil and gasoline. For optimal performance, schedule the tuneup at the end of the season. Then, all it should take is some fresh gasoline in the spring to get it started again.

Use a screwdriver to remove the air filter housing. (Photo by Katie Jacewicz)

If you do find yourself with a dead lawn mower and need a professional tuneup, expect a wait. Hale says he always sees a huge influx of needed mower repairs in spring because most people don’t realize their mower won’t start until their grass has already started to grow.

How to start a lawn mower

Check the gasoline. Is it the same gas you used last year? If the gas is older than 30 days, empty it from the mower and start fresh.

Check the oil. Each mower is different, but you should measure the amount of oil and check color consistency. Change the oil if it appears dark black in color.

Check the air filter. Clean or replace your mower's air filter annually. A new air filter typically costs $3 to $10.

Check the spark plug. Your lawn mower won't start if the spark plug becomes disconnected from the lawn mower. A new spark plug costs around $5.

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Editor's Note: This is an updated version of a story that originally posted April 4, 2012

More Like This

8 maintenance tips to keep your lawn mower running


Regular, preventive maintenance will prolong the life of your lawn mower. (Photo by Katie Jacewicz)
Regular, preventive maintenance will prolong the life of your lawn mower. (Photo by Katie Jacewicz)

Proper lawn mower maintenance can keep it running longer. Whether it's sharpening blades or getting a professional mower tuneup, follow these maintenance tips.


Took my push lawn mower for some repair(he works in his backyard and sells used ones in his front yard) last year. Ever thing work fine for about 2 month and stop working(had someone cut my yard the rest of summer). Just went and look at my mower and that repairman did not put in an air filter. I dont know if i can fix or not. pretty sure grass is in the intake.

I recently mulched the leaves in my yard at end of the season, I unfortunately struck the end of my culvert...engine immediately stopped.....I started it again but was a slight resistance when I pull the starter cord.......I mowed for about another 5 minutes and the engjne died.......I pulled the cord BUT IT NOW HAS NO RESISTANCE AS IF THERE IS NO COMPRESSION. It is a troy built 7.75 h.p. self proppelled 2 year old mower engine. What now? Is it economically feasible to have it repaired?

hi,my lawn mower just wont start. Help please? ihave cleaned the carburetter with a compreser, new fuel new engine oil, checked plug, sprayed carburetter cleaner.still wont start, it kind of back fires and gives a puff of smoke from the exust, can you please help. thank you eddie

I know this question may have been resolved but I'll throw in my two cents in case none of the answers already here work for the next guy. If you changed the spark plug and gapped it to .030, cleaned the carb and air filter the next thing I would do is take the plug back out and carefully remove the head so you don't damage the gasket under it. Usually nine bolts and when you put them back tighten to 17 pnds torque. After the head is off clean top of piston with a wire brush. Brush lightly so you don't scratch the piston. Next to that piston you will see two valves. Manually turn the flywheel on top of mower and make sure those two valves are opening and closing. If one sticks give it a couple light taps with a hammer or mallet until you free it. I won't go on to valve re seating but just put some oil around the valves and on piston top. Replace head and that should cover you. If not you need to rebuild the carb. If it is rebuilt correct and spark plug gap is correct and valves aren't stuck well then it may be time to debate the cost of a lawn mower repair shop or new mower. New mower is what I would do because every time I've ever put a foot in a lawn mower shop I've been robbed. And I've been in dozens.

Looks like we turned the lawn mower on the wrong side to change the blade. Oil leaked from the filter and the filter was all soked with oil. Mower won't turn on or start. What to do. Drained all the oil and filled it up to the level with new. Please advise what to do ?

Remove air filter and replace. If foam filter just rinse it our with gas. Remove spark plug and pull starter rope to blow out any oil if it got in cylinder. Replace spark plug since you have it out.

I was mowing my lawn when my tractor suddenly shut down I have changed all fuses and even tried jumping it to start but no luck. do you have any idea what could be wrong.

have you checked the oil level. Some small engines have a low oil shutoff sensor.

It's hard to say for sure without seeing your mower, but it sounds like it could possibly be the result of a clogged carburetor, or the spark plug might have become disconnected from your mower. Both of those issues can cause a lawn mower to abruptly stop. I suggest checking that your spark plug is actually connected to the mower (Mine has a small hook that slips over the spark plug.) If that doesn’t help, you might try using an aerosol-based carburetor cleaner to remove any blockage in the carb.

I have a Honda GCV160e lawnmower. I have used it several times and admittedly I haven't serviced it this year because my husband used to do that and he died in February. It would start on choke and then die. I thought it might be the filter or spark plug or both. I have changed the spark plug, oil, fuel, cleaned the filter and still it will only work on choke and then die. After eliminating air as I tried to run it without the filter, It still ran on choke and then died. There was fuel in the fuel bowl under the carburetor so I assumed it must be dirt in the carburetor starving the engine of fuel. I have taken it off and cleaned it and had the compressor on it and the central jet was oily and deposits of dirt came out and what looked like mud. I cleaned it twice and all the jets and put the compressor on it to dry it out. I have now put it back on my mower with new gaskets and now it won't start at all. Please help. I have spent two days trying to resolve this problem and I cannot think what it could be unless there is still dirt in the carb or something more seriously wrong with it. It worked no problem at all last year. The filter when I removed it was dirty and had a lot of grass in it. Many thanks! Julie

My lawn mower will turn over but won't start. I replaced the spark plug and I'm getting a spark. The spark plug is wet when I pull it out so its getting gas. There is good compression. The stator spins freely when I'm trying to crank it. It worked fine the last time I mowed which was a week ago. I don't know what else to check.

Is teh second time I had problems with how much oil I put on the lawnmower? I always put too much and it stops. How can I know exactly how much oil to put? How often do I need to add new oil? Please help!

craftsman ,gold series ,6.75 hp wont start when is hot ,cold no problem ,please advise ?????

no spark,put new plug in,checked shut-off switch and wiring.Checked magnet clearance and cleaned faces with sandpaper.Any suggestions?

My mower runs fine the first time I start it up. Then after the bag is full and I stop to empty it, the mower will not restart because the pull cord locks up. Sometime later, (I haven't measured the amount of time exactly) it will start fine again and I can finish the yard. I assume something is overheating and once it cools then it operates fine again. I checked the oil and there is plenty. Anything else I should do?

if you are waiting till the bag is completely full, there may be excess grass build up under the mower, so the blade can not move and that is why you can not pull rope. Also hose off the built up grass underneath the mower shield.

Could the string be caught up inside of the mower? The mower isn't even a year old yet.

check underneath for debris wrapped around the shaft above the blade

Have petrol and oil in my new tesco lawn mower but it won't start.

If it's a new lawn mower with all of its components, you may just need to prime it before starting it. You also want to verify that you do in fact have a spark plug and the spark plug wire is attched correctly.

My lawn will start and run for 30 one minute then it cuts off. I have changed the spark plug and the air filter and the same trouble occurs. Any suggestions before I take it to the repair shop and any estimates on this type of trouble.



i need to know how to do when to do and what it takes to do

If the place your always at is the place your always going stop wasting time preparing for a journey that will never be

Lawnmower is new, only used once, but now it won't start after I ran over a piece of fabric that was in the grass. Looked underneath and there's nothing tangled in the blades. Have two others that won't run, that's why I purchased this one. HELP!

you may not have noticed that string in wrapped around the shaft above the blade. May need razor knife to cut it off.

Hi there, When I pull the start rope (don't laugh -- I'm sure it has a better name than that), sometimes it pulls okay, but sometimes it won't pull all the way and snaps back (that hurts!!). I almost want to say the mechanism the rope deals with is clogged or something to that effect. Would it help to spray with WD-40? Would that help it not snap back sometimes? I never know when it will snap back. Any help would be greatly appreciated! Also, how much should a normal tune-up cost, approx.?

I had a generator with this problem. Timing was out because of a bent con rod? Or so I was told. Not worth the rebuild throw it away and get a new one

sounds like 1-3 things could be going on 1st thing i would check is starter there is a small plastic gear on the end of the unit alot of times from low voltage starts it can get stuck or it can also chew up the gear,2nd thing could be your battery does not have cold cranking amps it need to turn the starter.3rd put your hand on the top of the motor [were screen is] with your hand see if it can spin freely if it does'nt spin your motor could be locked up. let me know what you find hope this helped

new battery does not spin the motor over it only moves it one compression and stops, Seems to fall in the 3rd category above.

The battery measures 12 volts (just charged) but turning on the key I just get a "rattling" sound from the engine compartment, with the starter is not turning over the engine. The battery was low, so does this mean I don't have enough charge in the battery, even tho it reads 12 volts?

Motor spins freely bottom pulley turns but doesn't seem to have compression and won't start ?

i would suggest first thing you do is take step back look @ the unit is it leaking oil?,do youneed to change they oil?,is it dirty?,is air filter clogged?,is the fuel old? did you add old gas over new gas?,these are some of the problems u have to look for first then ,does it have spark,do you have compression tester if so i suggest you take a reading let me know what u have.should be between 65-80 or better psi if not,and u have less then what i specified then i would say you should take it to repair shop. if it does have good compression then do those steps i told you let me know what u have achevied.

Can't get mower to stay running. It shuts itself down and there is no fire going to the plug. Spark plug is ok. Air filter and fuel filter are OK. Just no fire to plug. Please help. ...

we bought a new battery and it still wont start not even the lights wont come on

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