By: Author John Cunningham. Published: 2019/06/28 at 3:18 pm
It’s more than a little disappointing. You bought a new mower so you could avoid breakdowns, troubleshooting, and hauling broken mowers to the shop. Don’t let this minor he-cup spoil the excitement of a new mower.
These types of problems are usually simple, and I’ll bet you can fix them right now.
Six common reasons a new mower won’t start:
1 Engine oil level low
2 Gas stale
3 Gas tap off
4 Choke Off
5 Bail lever off
6 Plug wire off
If all this stuff checks out, we’ll dig a little deeper, but we won’t do anything that will void your warranty.
1 Check The Engine Oil Level
This might sound too simplistic, but stay with me. Mowers are usually shipped without oil, and some mower engines are fitted with a low-oil level safety switch. This means if the oil is low, the mower won’t start.
Check the oil level; the average mower will take from empty .65 us quarts/ .6 lt of 5w30 or 10w30 engine oil. But only fill a little oil at a time, as too much oil is bad also; it will cause excessive crankcase pressure that may cause a no-start.
I wrote a complete guide about checking your oil, and you can check that out here.
Oil – Check oil level (the upper mark is correct)
2 Is The Gas Fresh?
This one might sound simplistic, too, but is there gas in the mower, and was the gas fresh? Did you know gas older than one month is likely stale unless you’re using a gas stabilizer? Was the gas can clean? A dirty refill can be a source of lots of problems. Clean out your gas can at the start of the season and fill it with fresh gas; use a gas stabilizer if you’re going to store your gas for longer than a month.
Gas stabilizer – Add to gas tank to prevent carburetor gumming. Check out the Gas stabilizer video.
3 Is The Gas Tap On?
Not all mowers will have a gas tap, but if it’s turned off, the mower isn’t getting gas and so won’t start. If your mower has a tap, you will find it by following the gas line from the tank to the carburetor or checking your mower specification in the owner’s manual.
I wrote a post about finding and using your gas tap, and you can check it out here, or check out the video here.
Gas On – Not all models will have a gas tap.
4 Is The Choke On?
All mower engines will need extra gas to start from cold. Your mower may have a choke lever or primer bulb that you press. More sophisticated models may have an automatic choke. Check which type you have by looking at the controls or referring to the owner’s manual.
I wrote a complete post on starting a lawnmower, which you can check out here (Link to starting a mower post).
Choke On – Some models will have an auto choke or a primer bulb.
5 Is The Bail Lever On?
The Bail lever, also known as a dead man’s lever, is basically the on/off switch in the form of a lever. It’s located on the handlebars and must be held in order for the engine to run and stay running.
Not all mowers will have a bail lever. If your mower has a blade engage control lever, which is usually fitted to higher-end mowers, then you won’t have a stop/start bail lever.
Releasing the bail lever kills the engine. If your mower is a self-drive, it will likely have two of these levers that confusingly look very similar. The stop/start bail lever will be marked with a stop sign or just colored red, and it is usually the upper lever. Check out “How to start a mower.”
Bail Lever – Most mowers will have a bail lever.
6 Is The Plug Wire On?
The spark plug wire lives right at the front of the engine and may not be fitted securely. If the plug wire is off, the mower will not start. It’s a black rubber-coated wire with a boot on the end. Check that it’s in place and secure.
Plug Wire – Check it is fitted securely.
Check Owners Manual
Obviously, one of the last things we all do is read the owner’s manual. But seriously, it’s worth checking; it may have a troubleshooting guide or some particular procedure required for your model mower. Check out their website, too; it may have a helpful video guide on assembling and starting the mower.
Why Does My Mower Flood?
This often happens when a mower is cranked over repeatedly without the mower starting. The engine gets way too much gas, and the spark plug gets saturated in fuel, which prevents it from creating a good spark.
You’ll know if your mower is flooded because it will stink of gas, and sometimes gas will leak from the carburetor. Turning the mower on its side during assembly can cause the engine to flood. It’s OK to turn your mower over; just be sure the carburetor side faces up.
To fix this problem, simply remove the air filter and take a 30-minute coffee break. This will allow the mower to dry out. Try starting the mower again, this time without any choke, and until it runs, leave the air filter off.
Pull starting a mower on full choke more than 4 or 5 times may cause the engine to flood. Check out the video on how to unflood your mower.
Flooding – Remove the air filter and take a coffee break.
Bad gas in a lawnmower, how to fix it? Drain the gas tank by removing the fuel line. Remove the carburetor fuel bowl, clean it, and refit. Fill the tank with fresh gas and start mowing.
Do pull-start lawnmowers have batteries? Pull-start mowers don’t have batteries. They don’t need a battery to run; the turning of the engine causes the coil to produce a voltage strong enough to fire the spark plug.
- About the Author
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John Cunningham is an Automotive Technician and writer at Lawnmowerfixed.com.
He’s been a mechanic for over twenty-five years and shares his know-how and hands-on experience in our DIY repair guides.
Johns’s fluff-free How-to guides help homeowners fix lawnmowers, tractor mowers, chainsaws, leaf blowers, power washers, generators, snow blowers, and more.