Walk behind Troubleshooting Starting techniques for small engines

spacecowboy

Forum Newbie
Joined
Jun 8, 2017
Threads
3
Messages
5
  • / Troubleshooting Starting techniques for small engines
When you trouble shoot a lawn mower to start there are only 2 things to consider 1) gas or 2) electricity (spark). So you would concentrate all of your troubleshooting efforts to determine which one isn't working quite well. Always consider the obvious 1st to make absolutely sure that the problem is not operators error. Go on with the INITIAL steps below until you succeed.

Trouble shooting strategy (initial)

• 1st is it choked when you try to start it? (observe the actions of the levers associated with the carburetor as you move the choke lever on and off when the lever is choked there is a extreme movement to the links closing the butterfly (for the least amount of air suction and a higher gas ratio)
• Does it have gas in the tank? Sometimes just by topping off the gas it will start. (yes the issue is between the gas tank and the carburetor)
• Check oil level - add oil or replace entirely (this has nothing to do with starting but make sure to check & correct this anyways)
• Is the spark plug wire plugged in correctly? which means you have to unplug it then replug it snug
• If it has a primer is it primed? you know the little bubble primer bulb you have to squeeze it several times
• Hondas and other manufacturers have a handle/lever that must be engaged to release brake and kill switch to allow starting sequence
Pull starter cord see if it starts. Try this at least 3 times.

Trouble shooting strategy step 2
shoot some gas or starter fluid into the carburetor and pull starter cord (if it refuses to start it might be an electrical issue) move on to step 2a. Step 2 will require that you pull the air filter cover and air filter off for access to the throat of the carburetor and spray starter fluid or gas directly into the carburetor.

Trouble shooting strategy step 2a
pull the spark plug and replace it with brand new, shoot some gas in the carburetor and pull starter cord.

••• Usually your mower will start after these steps if not continue below.

Trouble shooting strategy step 3
pull the spark plug & plug it back into the spark plug wire
take the loose spark plug and ground (touch) the threads onto the body and have someone pull starter cord - observe whether you are getting sparks jumping the nodes on your spark plug. Put on rubber gloves as you are doing this you'll have to hold the spark plug grounded to the body of the motor with your hands.

If you are getting sparks - reinstall spark plug the problem will be in the gas i.e.. Either replace or clean (bad gas, carburetor, hose from gas tank to carb, in-line carburetor filters, in-line carburetor shut off valve) these items. But do the carburetor last. Do not pull or clean the carburetor until you've checked and cleaned or replaced everything else above 1st. The hoses can be checked by removing and blowing on one end.

If you are not getting sparks - you have to change your "ignition coil" or you need a new spark plug. Always change the spark plug 1st. Caution: sometimes the spark is so little that you have a hard time seeing it with the naked eye. Buy an in-line spark plug detector on ebay or Harbor Freight Tools for under $5. And retest for spark if this might be the case.

If after performing these tests and it appears there is no spark there are many youtube videos that show you how to replace an ignition coil. My favorite is donyboy73. He's a pro and is very easy to understand.

What you really need to understand is that small engines are very simple in design and are really very easy to get to start. And I'm talking any small engine. The troubleshooting technique above can be used for all small gas driven engines.

Note: For Honda mowers, sometimes a honda lawn mower can start and die after a few seconds. So it really isn't a starting issue because it starts but this issue is that it dies after running a few seconds to a few minutes. Most troubleshooting guesses is that its a gas issue related to the carburetor. WRONG! Funny but this problem turns out to be a simple spark plug replacement. The problem here is a faulty spark plug. When the faulty spark plug gets too hot it fails to spark. The mower can get all the gas it wants but has that pathetic sputter because it fails to ignite the gas that is shoved into the chamber and dies. This is a real easy fix simply replace the spark plug.

Also with Hondas have a fuel shut off valve. When I've started my mower and it surges going faster and slower it was because I had the fuel shut off - turned to OFF! Because of the vacuum created by the piston pulling the gas mist into the chamber it can get a little gas through the shut off valve. But if you have the shut off valve on OFF and you tip your mower away from the carburetor to clean or inspect the underside or the blade no fuel will leak.

Print this out or cut and paste so that you can use it as a guide to start your mower. If you feel that you have to tear a lawn mower apart more than what is described above you are probably making a big mistake. Lawn mowers are quite simple and kind of simple in design and easy to start unless of course you forget to change the oil. Not changing oil will require extensive engine disassembly. Also if you're going to clean or restore your carburetor make sure to take pictures of the linkage prior to pulling it apart. I've seen where the linkages were put in the wrong holes keeping the mower from starting.
 
Last edited:
Top