• Skip to primary navigation
  • Skip to main content
  • Skip to footer

Mathews Blog

Professional Reviews & Buyer's Guides About Lawn Mowers

  • Blog
  • Lawn Mowers
  • Lawn Care

How To Start A Lawn Mower That Has Been Sitting For Years

Doyle Mathews By Doyle Mathews.

It is a common problem when you want to start your old lawn mower, but even new gas and new oil don’t make you happy. I’ll show you several reasons and how to fix them.  Of course, I’ll get some info for riding mowers too.

Table of Contents

  • Three Most Common Problems When Lawn Mower Doesn’t Start
    • Problem №1. The Old Spark Plug
    • Problem №2. Air Filter
    • Problem №3. The Dirty Carburetor
      • Gumout Fuel System Cleaner For Lawn Mower

Three Most Common Problems When Lawn Mower Doesn’t Start

I’m going to show you the three things I had to do to get my push mower to start after sitting for three years.

Problem №1. The Old Spark Plug

Remove the spark plug
Firstly, remove the rubber cap

The first thing you should remove the old spark plug requires a 5/8 deep well socket. It’s located in the front of the lawnmower, and you can break it loose.

After I’m replacing it with the RC12YC Champion brand, I’m sure there are other brands, but this is the one that I chose. Moreover, read the instruction because maybe the manufacturer recommends a special one. I put it in hand tight first.

ratchet with the 5/8 spark plug socket for the lawn mower
Use the ratchet with the 5/8 spark plug socket like this one

Then I take my a ratchet, and now you don’t want to over-tighten this. You want to snug it up. Just snug it up. Do not overtighten that. You’ll break it off.

Did the replacement and still doesn’t work?

Problem №2. Air Filter

The next thing you have to do: check the air filter. It can be nasty with oil stains and dust. The maintenance of the air filter should be done every year. So, replace the filter for the new one, and that’s it!

Problem №3. The Dirty Carburetor

To get to the carburetor, you need to remove these two bolts (see the photo below). American Standard, they’re 5/16, in metric, they’re 8 millimeters. I’d say use either a standard 5/16 socket or use 8 millimeters.

Carburator of the lawm mower
Find the carburetor and unplug the plastic case

This hose comes off of here, right there. Those two there, you got your carburetor right here. Be careful with this gasket, or you’ll have to get another one. Now, you could take the carburetor off with these two bolts and clean it up real good, soak it maybe.

But I would recommend to get some carburetor cleaner and sprayed inside and put everything back together. Just buy Gumout jet spray, carb and choke cleaner for small engines, like a lawn mower, and just sprayed it in the carburetor.
Cleaning the carburator
Clean carburetor with Gumout spray

You could take the whole carb off and soak it or spray it down real good and clean it real good. I’ve just tried spraying it because I don’t think it’s in that bad of shape. So I just sprayed it right in here, and I’m going to put everything back together and try to crank it back up.

Gumout Fuel System Cleaner For Lawn Mower

Gumout Multi-System Tune-Up Gumout Multi-System Tune-Up

  • Helps pass emissions testing, Lubricates upper cylinders, and Fights ethanol-related rust & corrosion
  • For Gas, ethanol, diesel and oil
  • For lawn mowers add 1 ounce per 1 gallon of fuel
Check Price
Updated. When sprayed cap with Gumout cleaner and get a successful start of the mower, I strongly recommend using Gumout Multi-System Tune-Up. It is a great solution for cleaning carburetor inside. You can see the results before and after in this video below (after 8.00 minute):

So, hook the hose back up. Don’t forget to hook the hose back up. And when you put this back on, don’t mess up the gasket. When it’s done, try to start your engine, and I think you will get success for your patience.

If you want to know more about repairing lawn mowers and other machines, I strongly recommend Comprehensive Small-Engine Repair Instruction.

For riding mowers update is coming soon.

 

Doyle Mathews

About Doyle Mathews

Doyle Mathews is a 39-year-old Lawn Expert Care that loves making gardens look much better. Qualified in lawn technology knowledge, teamwork, and attention to safety. Read More.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

ABOUT

Hi! Doyle Mathews and Peter Smith here.
Lawn Care Expert Site to test and review products for your evergreen grass!


DMCA.com Protection Status

AFFILIATE DISCLOSURE

Some posts may contain affiliate links. mathewslawn.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.

GETTING IN TOUCH

Phone: +1(679)-975-3524
Email: info@mathewslawn.com
Hours: Mon – Fri: 9:00am – 5:00pm
Saturday – Sunday: 11:00am – 3:00pm

4100 Spring St
Spring Park, MN 55384, USA

Follow us here!

 

  • Privacy Policy
  • Terms of Service
  • Contacts
  • About
  • Amazon Affiliate Disclosure

© 2019–2021 · MATHEWSLAWN.COM · ALL RIGHTS RESERVED