Lawn Mower Won’t Start: Fuel, Ignition and Compression Problems

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This video from Sears PartsDirect shows what to do if your walk behind lawn mower won’t start. There are a number of issues that could be causing the problem. A clogged air filter can keep air from getting to the carburetor and mixing with the gas. You could have a bad spark plug, or you could have an issue with old or contaminated fuel. We’ll show you how to check engine compression, check your fuel tank, clean your fuel line and how to access and examine your choke linkage, return spring and carburetor. This video will take you through the troubleshooting process step-by-step so that you can figure out what’s wrong and learn how to fix it.

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The video includes these parts. Look up your model to make sure you get the right parts for your lawn mower.
Air filter
Spark plug
Gas tank
Ignition Coil
Choke linkage
Carburetor rebuild kit

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Missy Evitt says:

The carburetor rebuild kit is $18 and a new carb is $24. Why wouldn't you just get a new carb?

Namrata Khindri says:


Lawn moreimnkk
You b h I will see

matt storch says:

Great video thank you, very helpful.

Waqas Saleem says:

You saved me so much money!!!!’ Thank you!!!!

dharmx says:

terrific video. thank you

Jeff Harper says:

Open flame n sparks? Until we turn it over to test for spark…lol

Shubert Truck says:

Your ads are annoying

Gilberto Ramirez says:

I'm a DIY'er for life. I fix my cars and motorcycles and everything else I have encountered in life to date, at 62 yrs young I have met my first lawn mower. I went surfing for help with the troubleshooting for this mower that won't remain running after I put some gas into the compression chamber as a troubleshooting step beyond verifying that there was spark to the new plug.
I came across your video. I just wanted to say thank you. this is a great job of adding video for each trouble shooting problem. great job. Thanks again.

Barbara Richards says:

Is it possible to be the gas cap. The yellow gasket broke off. It starts but stalls out. I sprayed starter fluid and it ran but then stalled again.

Scott Keller says:

totally wrong about the comment about if the screen in the tank is bad you need a new fuel tank wrong add a fuel filter 3 dollars instead of 50 dollars for a tank

Debra Dukes says:

Thanks so much appreciate your help. I only used it once so it has to be starter fluid because everything looks clean if not that stabilizer again Thanks for sharing Deb

Paul Brown says:

You should never us starter fluid or ether to try and start the engine, using this fluid can blow your engine apart and you will get hurt bad if it does. Instead use a little   gas in a spray bottle and squirt some into the carb and try and start the engine that way.

ChittinBricks says:

I like how MARSOC's official YouTube channel favorited a video on how to diagnose problems in a Lawn Mower. Guess even the most Elite of Marines are still prey to the notorious Green Weenie

Teena Dee says:

What if it was left in the rain and it's only been used once? Where is the best place to start

ns671fr says:

you wont always get compression on the tester, i fixed mowers with no compression reading but after I fix the problem such as timing, it works, so a tester is not always correct.

Kevin Voeks says:

Sears is garbage. I only buy tools from them

Jaster94 says:

Please explain the phenomena of double grounded spark plugs. Outside of cylinder I have spark. Inside has no spark. I'm still studying this issue, thanks

Screaming Dean says:

Thanks for the video, I left gas inside my lawnmower for months. However, I'm using a turkey baster to get the old gas out.

Nidal Shehadeh says:

use premium fuel in small engine , for some reason it works better and does not gum up in a carburetor after long storage ,
second if you have a fuel valve turn it off while the engine is running and wait until the fuel dries out from the carburetor ,
Fuel left in the carburetor for a long time will dry up and damage the carburetor , installing a fuel shut off valve is easy ,
If engine is hard to start remove the spark plug and use a propane torch burn off the Corbin residue and whatever might be on the spark plug , I do it until the Central Electric and the ground electroid get red hot , of course wait until the spark plug cool down before reinstalling it , in the Old Country Palestine we used to put a small amount of gasoline on the ground put the spark plug in the middle of it and set it on fire , that always worked to get us out of a jam ,

Virgil White says:

I have a 917258550 riding lawn mower. This belonged to a previous owner. I am trying to get it going. I can't get a spark from the spark plug. I have placed my thumb on the spark plug hole and turned it over. It pushed my thumb away! So I do have compression. How Much exactly – I do not know yet! I know it should be between 60 to 100 for this mower. I will get a guage eventually and check it.
No matter this brings me to the spark plug spark. I have replaced the spark plug and ignition coil. I gapped it to .011. I have unhooked the kill/grounding wire from the back of the ignition coil and still no spark!!!!!!!! What would be next to check????????????????? My best guess is to get a new flywheel for the magnets. Does the magnets on the flywheel have anything to do w/ the spark plug spark???

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