LawnMachines 300e Mower won't start-- Choke?

[Smokeeater]

Hey y'all, recently picked up a new lawn mower from a friend that did not start. It is a Lawn Machines 300E Briggs and Stratton mower. I thought it would be an easy fix, but I am stumped. I checked the spark plug and it seems fine. Not sure what to try next. I thought it might be the choke being stuck open but that ended up not being the case.

If you have an ideas let me know.

It’s either spark which you’ve checked, air filter clogged or fuel not getting through. Odds are it’s a fuel issue. Clean out the carb

 

[Joed756]

The spark plug was pretty clean so it must just be a bad spark plug. I'm going to re-assemble it now and do the spray test.

I'm not sure what this means, but you should consider a new plug. And yes, they do fail internally. I have seen plugs (usually Champion) that look just fine and spark just fine until compression is applied in the cylinder, then things expand and contract and you end up with a spark going around the insulator to ground. I've seen this with brand new champions in automotive tests. Simply try to start your engine in the dark, you'll see if there is an errant spark.

 

[gamma_ray]

well first lets see if it has spark.
If you have an carburetor cleaner (that is NOT non-flammable) and/ or starting fluid, or even a bit of gasoline, sprayed right into the carb for about a 2 second burst should be enough for it fire up, so spray a starting fluid into the carb, try to start, if it runs then dies, fuel delivery issue, either the carb still needs cleaned or the gas is bad/ water contaminated.
however this one is a choke version, not primer type.

now if it doesn't start at all, i would be looking for spark...remove the top engine cover (3 10mm screws) you'll see the ignition coil, and a small black wire going to the back of the engine, unplug that wire, it is the Kill wire.
try to start with that wire unplugged, repeat the earlier steps, and if it starts with the wire unplugged, there is an issue with the kill/brake assembly at the back of the engine or the wire insulation is rubbed off and shorting to ground (mower)
if it still doesn't start with the wire unplugged, bad coil.

** however i wouldn't mess with over sizing that jet

I really like Steve's videos and have watched many of them before. He's down to earth and explains things clearly, both rudimentary fixes and quirks he's discovered, such as this B&S carb main jet fix.

 

[Joed756]

The spark plug was pretty clean so it must just be a bad spark plug. I'm going to re-assemble it now and do the spray test.

I'm not sure what this means, but you should consider a new plug. And yes, they do fail internally. I have seen plugs (usually Champion) that look just fine and spark just fine until compression is applied in the cylinder, then things expand and contract and you end up with a spark going around the insulator to ground. I've seen this with brand new champions in automotive tests. Simply try to start your engine in the dark, you'll see if there is an errant spark

Alright Ill give it a shot. Thank you

I just checked the spark plug. It is not a resistor plug, its an E3.20. It had a resistance of over 100k ohms which is not right hah. Ill blow some air through the gas tank to see if that's the issue. I don't have the equipment to test the spark plug so I pulled it out and checked to see if it was corroded or anything. It looks pretty new so unless its an internal thing, it seems okay.
the engine is a 08P5020055F1
serial: 17 0427 54 29274

Ill spray something into the carb.

 

[Joed756]

Dude, seriously, replace your plug. It costs $5, it's the likely culprit and a simple job. Forget what it looks like, that doesn't tell you much unless you are checking the electrode for engine diagnosis, you are not doing that. Pop in a new plug and watch your worries drift away.

 

[Ronni]

Hey y'all, recently picked up a new lawn mower from a friend that did not start. It is a Lawn Machines 300E Briggs and Stratton mower. I thought it would be an easy fix, but I am stumped. I checked the spark plug and it seems fine. Not sure what to try next. I thought it might be the choke being stuck open but that ended up not being the case.

If you have an ideas let me know.

Here is a video that should help you.

 

[slomo]

Hey y'all, recently picked up a new lawn mower from a friend that did not start. It is a Lawn Machines 300E Briggs and Stratton mower. I thought it would be an easy fix, but I am stumped. I checked the spark plug and it seems fine. Not sure what to try next. I thought it might be the choke being stuck open but that ended up not being the case.

If you have an ideas let me know.

"How" did you check the spark plug?

slomo

 

[slomo]

How about a valve adjustment check? Pull the head and de-carbonize the combustion chamber? Clean the block cooling fins all the way around. Get an inline spark tester. Lastly best time to check spark is in the dark or low light conditions. Blue spark is good, orange is weak slash bad.

slomo

 

[Hilton43]

Hey y'all, recently picked up a new lawn mower from a friend that did not start. It is a Lawn Machines 300E Briggs and Stratton mower. I thought it would be an easy fix, but I am stumped. I checked the spark plug and it seems fine. Not sure what to try next. I thought it might be the choke being stuck open but that ended up not being the case.

If you have an ideas let me know.

Spray some starter fluid in the carburetor and try to start it. If it runs for a short time and then dies it is not getting fuel. If it doesn’t then check the compression, remove the plug and put your thumb over the hole and see if it blows your thumb away. An engine needs fuel,air, compression and a spark to run. When you find which one is missing you will know what to repair.

 

[Pecosbill]

Sometimes we over analyze and make these things more complicated than they may need to be. I’ve found that in most cases where a small engine won’t start it’s not the electrical system, although those items most certainly go bad. When a mower has been sitting unused for a while and there was even a small amount of gasoline left in the tank that gasoline, especially if it contains ethanol, will evaporate in the carb and leave behind a tiny bit of residue which will clog shut the jet on the carb. If this is the case, take the carb apart just enough to see the jet and run a very thin piece of wire through the jet, removing the clog. Put it back together and try to start it, without the air cleaner.

If the air cleaner has any dirt on it, clean or replace it. It may very well have been a dirty air cleaner that caused the previous owner to have trouble starting the engine and may well be why he just let it sit for a long time. When the engine sat unused, gunk developed in the carb from evaporation. I have found that these two things are the usual culprits in most of my starting issues.