Lawn Mower won't start - any help?

newtohobby

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Jul 22, 2006
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won't start,

first the primer bulb was broken replaced that.
no spark on spark plug - replaced that and ignition coil - ok now.
carburetor dirty, cleaned that out and fresh gas.

When I pull and try to start it, it does nothing, maybe at times a puff puff, but nothing else. Any suggestions?
 

FAST

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Mar 12, 2004
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What I have done when I has a gas mower to try and narrow the problem down, unscrew the plug, with thw ignition wire connected to the plug, hold the threaded area against the head, and pull the cord, you should see a spark across the gap.

If yes, not ignition.

And actually before you try the ignition test, if the plug is gas soaked, that will give you more info.

FAST
 

SchlongConery

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Jan 28, 2013
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But seriously though.... if it is puff puffing as if there is combustion but it just won't catch on to keep running, it is likely a problem in the carb. Like a stuck float or leaky gasket.

The fact that your primer bulb was rotted suggests that the gas has caused deterioration of the rubber parts of the fuel system . Gasoline now often contains ethanol which might not be compatible with the fuel system rubber and gaskets in older mowers.

Also, putting lawnmowers away like we do with old gas catches up in a few years and the carb gets all gummed up. You often have to take the carb apart and clean everything and replace the gaskets and o-rings etc PITA but lots of How To videos o youtube I imagine.


You MIGHT try using some Quick Start spray to see if you can get it to run on that shit for a few seconds to isolate it as a carb problem,
 

Ceiling Cat

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Feb 25, 2009
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Check if you are getting gas and spark. Pull the plug out and touch it against the body of the engine and pull the cord or hit the starter. If it is good you should see spark. Are get getting the smell of gas from the open spark plug hole? Spray the piston with piston cleanerthrough the spark plug hole to clean up fouling.

If the lawn mower starts practice by running a few cacklers down. If the start a cackling kick their heads off. Cacklers are like weeds, you have to get rid of them as soon as they show up.
 

newtohobby

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Jul 22, 2006
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I have done the spark plug test and its sparking after I replace the plug and coil. Its easier to see when you do it at night lol.

I took apart the carb and cleaned it out, looks ok so I don't know what else to do
 

Ceiling Cat

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Feb 25, 2009
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Do you smell gas coming out of the open spark plug hole, is the gas getting to the piston? It may be flooded, which means you will have to let it dry out.
 

jackson11

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Jun 6, 2010
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If this is your first time starting it this year it could be old gas in the carb. I used to see this all the time in a job I used to work at. I used to spray some Quick Start in the carb pull the cord a few times and would usually start right up.

Also as a safety note never lift up the lawnmower and start turning the blade with the spark plug wire on the spark plug. Always take the spark plug wire off the plug before turn the blade with your hands. It could start up the lawnmower (kind of like popping the clutch on a standard car). This may be common sense to some people however I was always amazed how many people would start spinning their lawnmower blade around. Surprised there are not more fingerless people out there.
 

newtohobby

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Jul 22, 2006
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Do you smell gas coming out of the open spark plug hole, is the gas getting to the piston? It may be flooded, which means you will have to let it dry out.
I think I can smell gas out of the hole. How do I know if gas is getting to the piston and engine?
 

Lady fisher

Member
Oct 13, 2015
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Shell gas no additives

But seriously though.... if it is puff puffing as if there is combustion but it just won't catch on to keep running, it is likely a problem in the carb. Like a stuck float or leaky gasket.

The fact that your primer bulb was rotted suggests that the gas has caused deterioration of the rubber parts of the fuel system . Gasoline now often contains ethanol which might not be compatible with the fuel system rubber and gaskets in older mowers.

Also, putting lawnmowers away like we do with old gas catches up in a few years and the carb gets all gummed up. You often have to take the carb apart and clean everything and replace the gaskets and o-rings etc PITA but lots of How To videos o youtube I imagine.


You MIGHT try using some Quick Start spray to see if you can get it to run on that shit for a few seconds to isolate it as a carb problem,
I use shell premium gas no additives great for small engines like lawn mowers and snow blowers

Always run your small engines dry of gas at the end of the season

Get a honda engine and take care of it ........my mower starts first pull every time
 

John Henry

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Apr 10, 2011
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Some engines like my 4 hp Yamaha boat motor are not supposed to be run dry . I use a good quality stabilizer in the gas and leave it . Not only that I use ethanol free gas in all of my small engines . It's available in regular form . Just gotta look for it . All Shell High Test gas is ethanol free as well . You can use that . Will not hurt the engine .

http://www.amazon.com/PRI-Fuel-Stab...qid=1461997620&sr=8-9&keywords=gas+stabilizer good stuff

Dry off the spark plug put it back and leave it for a day . Like other people have said , quick start is your friend . Just spray it in the carb .
 

whitewaterguy

Well-known member
Aug 30, 2005
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Some engines like my 4 hp Yamaha boat motor are not supposed to be run dry . I use a good quality stabilizer in the gas and leave it . Not only that I use ethanol free gas in all of my small engines . It's available in regular form . Just gotta look for it . All Shell High Test gas is ethanol free as well . You can use that . Will not hurt the engine .

http://www.amazon.com/PRI-Fuel-Stab...qid=1461997620&sr=8-9&keywords=gas+stabilizer good stuff

Dry off the spark plug put it back and leave it for a day . Like other people have said , quick start is your friend . Just spray it in the carb .
Shell without the ethanol is the only way to go...even for my harley, and especially for everything motorized that sits around with no use over winter
 

Wigglyguy

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Jun 17, 2014
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I had the same problem. Replaced all the same parts. Then finally replaced the rubber diaphragm under the carburetor and it ran like a top. Good luck.
 

RickC

Member
Feb 10, 2008
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Rust on your Rotor is my guess , no spark is a good sign . Pull recoil , sand rotor ,
 

james t kirk

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Aug 17, 2001
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The fact that your primer bulb was rotted suggests that the gas has caused deterioration of the rubber parts of the fuel system . Gasoline now often contains ethanol which might not be compatible with the fuel system rubber and gaskets in older mowers.
Ding ding ding.

Ethanol is the scourge of infrequently used engines, small engines, old engines in classic cars and modern Audi Q5.

Gasoline with Ethanol should be avoided at all costs.

Shell is the only company I am aware of that does not use ethanol and I use it exclusively in my old car and small motors. I used to think it was nonsense, until I suffered severe impacts from ethanol laced gasolines. You take apart your carb and the bowl will have a green moss like slime on the inside of it. It rots rubber and plugs up all the orifices.

Never use ethanol laced fuels if you can avoid it.
 

SchlongConery

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Jan 28, 2013
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Check if you are getting gas and spark. Pull the plug out and touch it against the body of the engine and pull the cord or hit the starter. If it is good you should see spark. Are get getting the smell of gas from the open spark plug hole? Spray the piston with piston cleanerthrough the spark plug hole to clean up fouling.

If the lawn mower starts practice by running a few cacklers down. If the start a cackling kick their heads off. Cacklers are like weeds, you have to get rid of them as soon as they show up.

Piston Cleaner?
never heard of the stuff and I I am a gearhead and crank case chemist having rebuilt or otherwise disassembled perhaps a dozen various types of engines. No chemical will remove carbon buildup on the head of a piston. Only scrapers and do that.

Besides, that would have nothing to do with his lawnmower running.


Or did you just pull that out of your gas hole?
 

SchlongConery

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Jan 28, 2013
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I had the same problem. Replaced all the same parts. Then finally replaced the rubber diaphragm under the carburetor and it ran like a top. Good luck.

That is so typical of this kind of problem. Especially with ethanol now. All it takes is one O-ring or gasket leaking allowing the unmetered fuel to get into the engineand resulting in an incorrect air fuel ratio that will not support combustion

For such a simple carburetor, those little engines sure are sensitive
 

newtohobby

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Jul 22, 2006
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I put a bit of gas in the spark plug hole and it started for a second. Should i change the carbuerator?
 

SchlongConery

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Jan 28, 2013
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By all that you have said, it seems that the carburator is the culprit.

I have no idea what engine it is or where you get parts etc. But if you are handy, I'd see if you can find a rebuild kit of gaskets or if you can find a new carb, then do that.

But fixing these little fuckers gets expensive fast and unless you are a really good small engine mechanic, they never seem to run right.

. Sears has a decen mower on sale for $219 this weekend that might save a lot of hassle. http://www.sears.ca/product/craftsm...gital&extid=affiliate_comj&affiliateid=749547

Here is coupon code
 
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