7 Simple Reasons Your Mower Won’t Start
What’s more frustrating than a lawn mower that won’t start?
There are a lot of things that can cause your mower to have some trouble starting up.
But don’t take it to the costly repair shop quite yet.
First, see these 7 simple reasons your mower might not start.
1) Out of Gas
It sounds crazy, but it happens!
Make sure you check your fuel level each time before you fire up your mower.
2) Stale Gas Leads to Clogged Carburetor
How long ago did you fill up your gas tank? And how old was the gas you used?
Gas only has a shelf life of about 30 days because of the ethanol it contains. If you have old gas in your tank, the ethanol may have caused corrosion and clogged your carburetor.
Learn more about the dangers of ethanol in power equipment »
3) Clogged Fuel Filter
The purpose of the fuel filter is to filter out all of the sediment from the gasoline.
This filter can get clogged up from normal sediment, or from stale gas containing ethanol.
The lack of proper fuel flow to the carburetor will prevent your mower from starting.
If this is the case, the fuel filter will need to be replaced.
4) Dead battery
Batteries typically last a long time, but there isn’t always a warning sign that it is going dead. Check your battery with a voltmeter to see if it’s lacking juice.
If you have a 12V battery, the voltage should read very close to 12V. If it’s less, your battery may not have enough juice to start the mower.
5) Bad Starter Solenoid
If you turn the key in your ignition, and hear a clicking sound, it is probably your starter solenoid.
If you notice this clicking, your best bet is to install a new starter solenoid.
6) Disconnected or Dirty Spark Plug
Did you recently perform maintenance? Maybe you left your spark plug wire un-hooked! Be sure to check this out, this is a quick and simple fix.
Your spark plug could also be dirty or damaged. Spark plugs are cheap, so try replacing your spark plug.
See how to service your spark plug here »
7) Dirty Air Filter
The carburetor needs air to make the engine run. If the air filter is dirty, it may not let air to the carburetor. Also, if the air filter is torn, debris could have flown into the carburetor or engine and is preventing your mower from starting.
Learn how to check and change your air filter here»
Did any of these quick-fixes solve your starting problem?
Always remember to keep up with routine care and maintenance to keep your lawn mower in top condition and to prevent some of these problems from occurring.
Featured Parts and Products:
Related Posts
How to Start and Stop Your Craftsman 46” Automatic Transmission Riding Mower →
How Lawn Tractors Work →
How Zero Turn Mowers Work →
John Deere D100 Series Lawn Tractor: How to Start and Stop the Engine →
Thanks for the help tips for the riding mower. I noticed that the picture was a pushmower and expected tips for that type…thanks again.
I’d like to add another simple reason my mower(Lawnboy) would not start…
I don’t use the rear bag so I have a plug to block the grass exit hole. This plug has a metal lever to lock it in place. Well, there is an interlock switch for this lever. If it’s not fully inserted, the mower won’t start. It’s only once I had pretty much completely disassembled the whole mower and noticed a wire going to the back near the exit hole that I realized this…
Now I know!
Lots of good vital points. Suggest also using premium fuels, additives IE; Marvel Mystery Oil, a battery maintainer but also remove ground while not using to prevent a parasite drain. Using a test light can help locate such a drain connect pigtail to battery post or disconnected wire and touch the point end to the other, no light indicates No Parasite Drain.
Thanks for Keeping in touch
My safety cable came in a few days and to my surprise I was able to fix my mower When I try to fix things always hear
” I love do it your selfers”
Years ago I signed up for a class learn fix small engines even paid
but they never had the class Sorry I don’t know how to fix small engines better than a paper route
Bruce
Thanks for sharing. This is great info and good reminders.
When I first start my mower, it starts up find. After I stop the engine to empty the bag, I have a hard time starting it. Have to let it set for about 10 minutes before it will start again, What could be causing this problem??
Joe
Joseph, there are several things that might cause this. Sometimes heat soak will cause a marginal coil to glitch, cooling down will allow a restart. If your carb inlet valve leaks, it will cause a too rich mixture (you arent using choke or primer bulb to start a hot engine, right?) You can sometimes sidestep this problem by fully opening the throttle (and choke, if it’s manual) and the resulting leaning out of a too rich mixture will allow it to start.
I WILL APPLY SOME OF YOUR METHODS TO MY GASOLINE GRASS TRIMMER. THANKS
For both push and riders, some have a low oil shut off switch. Make sore to check your oil EVERYTIME you put in gas and before use!!!! Also, with riding mowers, there could be a safety switch that is not engaging. On riders, there is typically one under the seat. If you are not sitting in the seat correctly, the switch will not allow the engine to start. There may be other safety switches too (ie. Parking brake, PTO/deck engaged, etc).
The author’s statement, “Gas only has a shelf life of about 30 days because of the ethanol it contains. ” is completely FALSE!
Untreated gasoline can last past 6 months, this is from personal experience.
Treated gasoline can last a few years, again, personal experience.
Always treat my gasoline with FI cleaner, Chevron Techron.
Ethanol is BAD for fuel systems, corrosion on carb & fuel lines.
Hey mate Glyn my name, I was wondering if you had any advice I have this mower with a self priming system won’t start if cjrcked spark but don’t know anything about d priming systems it’s joined to carby so on leaver had option of choke start or run rabbit to turtle not sure of brand cheers mate
riding mower runs for about 20 mins and then shuts down. Have to wait about 20 more min. to restart and finish mowing. what could the problem be?
Hey Floyd!
There could be a number of things that could cause this.
You could need to clean out your carburetor, or you may need to replace your ignition coil.
Often times when the ignition coil goes bad it will run until it gets hot and then shut down and not restart until it has cooled down again, which seems like what you have going on!
It could also be as simple as a clogged fuel vent, loosen up the cap on your gas tank and see if it runs okay.
Hope this helps!
Hola I recently purchased a Husqvarna lawnmower with a Briggs and Stranton engine. I live two hours away from the place I purchased it from. Down in the mountains of southern Oaxaca in Mexico. When I got it home it started right up and I ran it for about five minutes and stopped it to put gas in it. Then it wouldn’t start for half an hour. Once it started again it ran fine till I ran out of gas. Then I had to wait for another half hour. It is next to impossible to get help from the store. Customer and service don’t go together here very well. Is there anything I can do to fix this? I know if I ever get it back there they will have it for a couple of weeks and I’ll bring it home and it won’t be fixed. Any suggestions will be greatly appreciated.
Thank you,
William A. Nemeth
i have a john deere riding lawn mower run’s but blow”s gas and oil out the muffler. is this the floot in the carb.
Sounds like your needle valve in you carb is sticking and letting oil to run into your crankcase. Check your oil and see if it is over ful and smells like gas. If yes then you need to clean your needle and down in the hole where the needle goes, or you can put a cut off valve inline between the tank and carb. Just remember to turn it on before you start and off when you are through.
Ralph
This is under you float sorry I forgot to mention that.
Running weak wants to cut off when going through thin and especially thick grass.Was only able to cut half the yard.
Are you mulching, or bagging your grass clippings. If the mower blade is dull it could be clumping up grass beneath the mower deck which would cause more stress on the engine.
push lawnmower, briggs and stratton about 7 years old stopped starting.
gas good, filter good, changed spark plug.
found that if i manually pulled the governor while pull starting it would start right away and run like a champ.
don’t see any missing or brokrn parts. the governor spring pulls it the opposite way to what i have to pull on to start it. Advice
thanks,
Al
I have the same issue except there’s a clanking sound. Did you get yours started?
Z turn is getting gas and i changed the spark plugs, turning over but wont start. The battery get weak so i jump it.
Seems let the carburetor may be trashy. Low battery and oil flash on display. How do you reset those.
Help
Greg, do you have a manufacturer and model number for your mower?
Ariens riding mower will not start. When trying to start it seems like the battey Would be weak. Battery is good. It does the same thing when I try to jump start it. Any ideas
Have you checked the alternator and starter solenoid too?
yes it will start but wont stay running
O have a John Deere Z 225 with Briggs engine…Battery checks at 13 + volts but it won’t turn starter without a jump or connected on the charger on fast charge for an hour. Once it starts it uns fine. Starter see,s okay…Is there a cellenoid or a coil that could cause this problem and if so where are they ?
Sounds as tho you maybe using a digtal VOM they are so sensitive they can read the residual voltage in the batt ,but it will not have enough to turn the starter.
SHORT VERSION—BAD BATTERY
I have a Honda harmony hrv216 bm it will start but will not stay running the carb is fine and has new gas
I bought a craftsman lt1000 ran like a champ ran out of gas put gas in it now it wont start thought it was carb bought a new one it aint the spark plug is new.. new starter and starter cylinoid…
I have an old briggs lawn mower, probably from the 60’s. The only way I can start it is by placing gas into the carb then I have to run it at full speed when started otherwise it will stall, especially while cutting at a downward angle. I was cutting the lawn today and it ran out of gas, so i replaced the gas with fresh gas and no matter what I do, it won’t start even when I put gas into the carb. What can be wrong? I don’t want to let this mower go to the dump as I want to restore it to good working condition again.
Possible partially-plugged fuel filter..(?). hard time getting enough in to start, but once started, pulls enough to run. I had a small motorcycle that did the same thing…
After standing up 10hp snapper to change blade it will not start. Have checked switches, fuel vent, spark plug etc. but will not start. Have now a dead battery but I can jump it with truck. But still not catch. Help
Oil runs into cylinder. I have done the same. Pull the plug, and drain. (May have to drain oil out first?) Even had oil run out of enhaust once!
need help. I believe that it’s the carburator, It seems to let too much gas out and then floods out.
Maybe valves. Is it blowing gas up to air filter or close than probably in take valve
I would like to know where the spark plug is for a Husqvanra Riding Lawn Mower is and how to change it? The model # is 968999245/CZ3815
https://www.manualslib.com/manual/74277/Husqvarna-968999245-Cz3815.html
Got an old Murray lawn tractor with a Briggs engine. Brand new battery but no power. No clicking or anything. It was in neutral and blades were disengaged. Spark plugs good and connected, battery connection good. Starter maybe???
No clicking or turning ? Check solenoid little terminal for 12 volts when key turned to start , if does have change solenoid . If no volts check for Fuse in wire off of battery, if fuse ok , probably starter switch. . Good Luck
A less common and obscure reason for an engine starting but rapidly cutting out is a broken splasher/flicker on the con rod. Once the engine starts, lack of oil causes the moving parts to rapidly heat, the aluminum from the rod gets smeared over the surfaces in contact further increasing friction. The load increases on the engine and it stalls.
How to tell if the fuel pump is working? Kohler 25 hp
My Husqvarna has always been trouble free until, this year when, trying to pull the rope it won’t pull but, very little. Seems to be knotted up.mower was stored in garage with no gas in it. Can’t figure it out. Any ideas?
mabey mouse nest inside starter housing
I have a husqvarna rz 5424. it will crank and run if you pull off the two coil wires. plug them back in and it dies. what the heck.
I have a Deere d300 and I have to prime it to get it started. Once it is started it runs fine. What is the reason for the no start issue.
I have a Murray 42910X92A riding mower with a Briggs & Stratton engine. I just changed the blades and had it running fine, finished about 3/4 of the yard when it suddenly died and will not start. Turning the ignition does absolutely nothing. No crank, no click. Battery is fully charged and I couldn’t find any loose/damaged wires. Any suggestions on what to check next?
I have Mtd riding lawn mower
I replace safety switch and solenoid. engine cranks. It has spark and gas but still wont run.
I hope you can help.
My Murray 20 hrs has gas to engine but no spark turns over good, filter is new, plugs get gas but no spark, spark plugs new !! So what’s my problem ?
I just got my owner back from the shop! It stated first pull. I cut some grass enough to fill the rear bag! When I release the hand it shuts off. I empty the bag and put it on. I go to start and nothing. By the why I used new premium gas, when it cools it will start again! What could be the problem? It’s a craftsman gold push mower
I have a husqvarna and I changed my spark plug and air filter and even cleaned out the tank and the carburetor and it will not start. When I hit it with starting flui it will run for like 2 seconds but turns right off after that. It’s a push mower by the way can I get some help
We have a new Snapper push mower…used very few times last summer and ran well. Could not get it started this summer, so we got some starter fluid. Started, but would not keep running. Drained gas tank, clean filter, carburetor clean. Help!!!
I have a riding mower,with a 14hp engine,started it one day and had lot of black smoke around it.The air filter was very dirty,would that cause the oil and gas to mix and spray out of the crankcase assembly.One place said it was the assembly.Could it have been the clogged air filter and pre filter causing it.When I drained the oil,it was mixed with gas.just strating it used about a quart.When I took the spark plug out gas poured out of it too.I need help as Ican’t afford to have it repaired.Just barely making expences.I would appreciate any help you can give.
Turn honda pust lawn mower on side to change blades now it will not start
Have Murray 21 inch push mower, clips won’t stay in handle, bought new ones and locking ones, nothing holds, now have duct tape on it. The engine was running fine, only 3.5 months old, but will not start, air filter looks good, spark plug looks good. The store says it’s past the “90 days return date” so I can’t return and warranty seems to be junk since I can’t get help. Any suggestions for a non-mechanic?
Also, old Troy Built 42″ rider, starts fine and runs, but won’t go, cuts, but won’t move. Some came out of the deck, so replaced blade belt. Could it possibly be the drive belts (these are different from the blade belts, correct? Please give suggestions, my grass is so tall and neither mower works!
Have a johndeere riding mower it started good mowed most of lawn stoped for awhile to rest when tried to start would do any thing my batter is new,can you give me some pointers
I have a Craftsman riding mower with a Briggs & Stratton 21 hsp OHV engine. Ran it out of gas and now can’t get it to even try to start. I had the carb rebuilt and fuel system cleaned out about 6 running hours ago and it’s been fine until now. I pulled each section of fuel line, checked for clogs, turned it over with each section off and fuel comes out. Even shot ether/starting fluid into it and it won’t even try to start on the ether. Cleaned the air filters, Never run anything but non ethenol gas in it. Unit has 100 hours on it total. Been working on it several days now, I’m out of ideas except take it to the shop and I need it badly now not when they get to it around October or use it for target practice!
I have Husqvarna push mower and it starts when you first start but after cutting the front and go to the back yard after cutting it off, won’t hit or try to start. Like it has to cool down. What could be the culprit invading my Huskymower?
I had my starter rebuilt now when I turn the key the starter engages but sticks and won’t disengage. Should I shim the starter a little?