Lawn Mower Won't Start

      

Dirt is the Number 1 problem with both 2- and 4-cycle lawn mower engines. This is because the engine works almost at ground level where spinning blades generate a whirlwind of dust that chokes engine air filters, fuel filters and lines, spark plugs, controls and other parts.

This 3-part article deals with lawn mowers that won't start. Even after following the directions here, you may not be able to get the mower going. This is because some symptoms are so obscure in engines that it takes a professional with professional equipment to spot the problem. But, in general, malfunctioning engines show symptoms that are easy to identify. Check the problem in an orderly fashion, as detailed below, and you usually will be able to find the solution and save a trip to the repair shop some hot, muggy Saturday morning.

PROBLEM: ENGINE WON'T START:
The procedures:

• Are the engine controls properly set on "start"?
• Does the engine have fresh fuel in the fuel tank?
• Is the tank more than half full of fuel? Is the spark plug wire attached tightly to the plug?
• Going down this checklist:

1. Trace the sheathed control cable from the handle of the equipment to the throttle on the engine. The throttle should be fully opened with the control handle setting on "start". As you move the control lever from "start" to "fast" to "stop", the cable should be clamped so that it operates the throttle. The cable can be slipping in the clamp just enough to cause the throttle to malfunction.
   Move the throttle control to its open, or "start" position with you fingers. Or, push the throttle forward, toward the front of the engine. You may have to move the control lever with your other hand to ease the throttle open. If the throttle cable is slipping in the clamp, tighten the clamp screw with a screwdriver after you push the cable forward toward the engine until the throttle stops. The throttle is now in a fully open position. Set the handle control lever on "fast" or "start" and tighten the clamp.
2. If the engine now starts, let it run several minutes. Then pull the control lever to "stop". If the engine slows but does not stop, loosen the cable clamp and pull the cable just a tad toward the control lever until the engine stops. Then tighten the clamp. Go through this sequence until the mower stops and starts on command of the control lever. No gas or dirty gas, mower manufacturers and professional lawn mower repair persons report, are two big troublemakers for engines that won't start.
   Dump out the gas in the tank in a safe spot and refill the tank—even though you think the fuel is perfectly good. If you are just starting the mowing season, start with new gasoline; last year's gas can be weak.
3. Fill the tank with fresh fuel. Low fuel in a tank sometimes can prevent starts. This sounds strange, but it is true.
4. Spark plug wires, through engine vibration, can become loose. The engine doesn't get any spark so the fuel can't be ignited.
   Pull the wire off the plug. You'll notice a thin metal "socket" which goes over the plug terminal. With pliers, carefully crimp the metal socket. Now replace the socket on the plug terminal.

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Comments You\'ll find a guide for troubleshooting ignition issues on My Lawn Mower Won\'t Start. #23 - Jon - 01/21/2010 - 05:07 guess i ran my 2 cycle without enough oil in the gas. won't start now any suggestions, do i need to replace rings and hone cylinder? #22 - Brian - 11/15/2009 - 16:06 Mr. Hacker\'s advice about gas directly into spark plug hole worked great! Thanks Guy : ) Mike #21 - Mike - 10/24/2009 - 16:38 if i start the lewnmower i hav to push th elittle button to inject the fuel if i stop pushing the button the lawn mower gos off #20 - michael - 10/07/2009 - 16:33 thank you! thanks to your suggestions, i didn\'t have to get a man to come fix my lawn mower, i did it myself...thank you!!!! #19 - DSmith - 08/22/2009 - 14:34 Craftsman Mower does not start. It will if I unscrew the Bow Drain srew My Craftsman mower does not start. But if I unscrew the Bow Drain screw located at the Float Bowl a couple of turns it stars fine but the gas will leak out. I replaced the oil,gas,spark plug and air filter. I also removed and cleaned the float bowl. I don't know what to do next. Thanks for your help. Luch #18 - Luch - 08/16/2009 - 21:45 TOO MUCH OIL... DRAINED IT... CORD WON\'T PULL... Ok... have a 6 year old Tuchsumse... ran well... 1st time using it this season... over did it on the oil... drained some oil... now pull cord won\'t pull so I can start engine... no clue what to do... suggestions??? RT :-( #17 - RALPH - 06/23/2009 - 16:02 google f.a.q. for your brand Google how to... just about any question you can think of, google has the answer. We have a lawn mower page f.a.q. except my lawn mower won't start, what do I do? Often times the lawn mower companies will post actual frequently asked questions. #16 - john wright - 06/16/2009 - 15:58 Lawn Tractor wont start One year old MTD w tecumseh engine. I've replaced the oil, put in fresh fuel, changed the spark plug, and swapped the battery, but still when I depress the clutch/brake, engage the choke and turn the key I get a single "click" and that's it. It wont start. Any ideas? #15 - David - 06/11/2009 - 09:34 gas leak Gas is leaking out of the carburator! How do I fix it? #14 - brandon - 06/07/2009 - 09:20 Mr. Hacker Well if your clued out about engines and or lazy - or both like me then just do this - remove the spark plug and put clean gas directly in that hole then replace the plug start the thing and go mow your lawn. When your finished your carb should be clean too! #13 - Steve O - 05/31/2009 - 15:27 Put old gas in your car's tank, with enough fuel all ready there it will be diluted enough in that big ole engine to be burned up. Way better than dumping it on the ground! #12 - Jim - 05/17/2009 - 14:26 new gas lawnmoyer wont start My moyer,I used one time.Ithan let it set in my garge for 4 yrs.I put new gas /oil in.Itried to start it ,but It wood not start,It wont even try to start.Do you have any Ideas? Thank You, Pete #11 - Peter Grass - 05/04/2009 - 11:53 craftsman mower please help me find info on c riding lawn mower with no spark and smart start ignition i'm not smart enough to find anything.........thanks #10 - tim - 04/20/2009 - 18:25 stuck with no spark hey i have n o spark either but there seems to be some voltage going through the plug lead as when i hold the metal end and wind over engine there is a small tingle. i have sanded rust off flywheel and have set points at 0.08, 0.010, 0.011, 0.013, 0.015 ,0.018,0.020, 0.023 inch and still no spark. i have tried these gaps with new plug and still no spark, i cut a wire which ran onto the engine and i suspected i ran to a cutoff switch from there but to no avail. there is still a wire from coil to one of the bolts holding in on which i think is a ground although it is a small wire. any ideas where im going wrong? #9 - zak - 11/16/2008 - 16:13 ouch I had a buddy spin the blade while I pulled the cord on my mower.I started alright however he lost his hand.Pissed me off because I had to shut the thing off an call 911.And the worse part was after the carted him away I tried to restart the mower an it wound not start.Rat fart!!!!!!!! #8 - Brian - 08/10/2008 - 05:59 inspector got one for self propelled: check your spring on the handle used to engage...depending on the age of your mower ...check the cable as you lift the handle up and down does it pull tension and then retract as you release...if this is the case then turn your mower on and engage the propell handle use a pair of pliers and pull alittle more tension on your cable ....willing to bet this work's...if it does all you need to do is remove spring shorten or get a shorter one re-install it ...and git back at it! #7 - jake - 08/08/2008 - 13:32 Self Propelled :-( My toro self propelled lawn mower has been great but all of a sudden the self propelled feature on it does not work. I am a single mother and don't have the money to take it into the shop. I am way good at fixing things I just don't know where to start with this Any ideas #6 - Camogirl - 07/28/2008 - 17:24 enthusiast FYI I have a 6.0 HP Briggs motor on my Snapper self-propelled mower. Engine model 12H802. Thanks for these extremely helpful suggestions. After all of them I was still having issues and finally resolved this afternoon. Replaced spark plug Replaced air filter Checked fuel line Put gas into the spark plug hole and the engine fired up for 2 seconds with thick black smoke and then died Put gas into the carburetor after taking off the air filter. Same result. Engine started and died. So I knew that I had a fuel delivery problem. Took off the air filter plastic holder (3 screws). Be careful not to twist the hoses too much. When the air filter holder is off then you can see the carburetor. I took off the carburetor (2 bolts) and flipped it over. You will see a metal bowl with a bolt in it. This 'bolt' is called the 'bowl nut'. Don't ask me why a bolt is called a nut. Take off the bolt carefully and slowly. Drain all the fuel out. Clean the holes in the bolt (one through from side to side and one from top to bottom which meets the side-to-side hole. Clean with a sewing needle very carefully. Also look into the carburetor area where you took the bolt out of and you will see two holes. Pierce those with the sewing needle and very carefully clean out all the gunk. If you have carburetor cleaner or can buy some, soak all these pieces in carb cleaner overnight (I did not do this). If you are feeling very adventurous take apart the entire carburetor, clean with carb cleaner overnight and then put back together (again, I did not try this). Then finally put the bowl nut back and put the carburetor back. Fill fresh fuel, prime and it should all work. The problem that I had was the very narrow (0.25mm) vertical shaft in the bowl nut was clogged (I had not used the mower in 2 years). http://nevadawalrus.com/tips/tip2b.html #5 - ararshars - 05/19/2008 - 12:38 Dumping gas "...it is almost universally illegal" So is entering the country without documents and talking on your cell phone while driving. Let's be honest. No one cares what's illegal anymore, just what they can be caught doing. #4 - Bob - 05/19/2008 - 11:41 Can't pull recoil starter grip When I try to pull on the recoil starter grip to start the lawn mower it does not move. What do you suggest? My gas and oil areas are full. #3 - dee - 05/02/2008 - 18:57 I cannot believe this page encourages readers to "Dump out the gas in the tank in a safe spot and refill the tank". Not only does dumping do lasting, serious damage to the local soil and seep into YOUR drinking water, it is almost universally illegal. Please dispose of gasoline properly!! #2 - John - 03/27/2008 - 13:31 Check the air too As well as fuel and a spark you engine needs air too. Make sure your air filter is not clogged with dirt or grass. #1 - mower air intake - 10/29/2007 - 23:41 Mr. My Craftsman mower doesn't start (no any sound). I found the throttle does not move though the control lever can be moved between "Low" and "High". There are 2 wires that control the throttle each has a spring. I can figue out which spring lost its strength. It seems to me that the throttle is at the direction towards the engine. I don't know it is open or closed. In this case, do you think the throttle is still the reason for the no starting problem? Thanks for help. Jerry #0 - Jerry Lee - 10/07/2007 - 21:21 Name Title Comment To prevent automated Bots form spamming, please enter the text you see in the image below in the appropriate input box. Your comment will only be submitted if the strings match. 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