engine problem

[Dpmulvan]

Does a John deer even have a magneto? Does it fly? As others said it’s probably your coil an easy quick check with a $5 spark check tool. Someone mentioned putting a meter on it to check ohm but you might not get a bad reading with an intermittent coil issue. Start simple, obvious, easy and cheap.

 

[Jim K.]

John Deere LA 115 19.5 briggs and stratton starts cold runs 5 minutes and cuts off. loses spark. Has a new spark plug new gas filter, new air filter. Anyone else have this problem?

Sounds like the coil is breaking down after it heats up, I had that problem once could not figure out the problem, I called my brother in law that lived 500 miles away told him about it he said change the coil and wire sure enough that fixed it

 

[Jim K.]

Sounds like the coil or Magneto for whatever kind of electrical system that's on it is breaking down after it warms up needs replaced

 

[bertsmobile1]

This happens sometimes when the Low Oil Level safety triggers

Quite true but not on a LA because they don't have one

if the engine runs for 5 minutes then dies after heating up...the carb is fine...the coil or grounding is an issue along with a possible gas cap vent issue...if you test the coil resistance and its good...gounding or gas cap is an issue. .if the engine stopping is an inconsistant time then debris in the carb...fuel line...or gas cap vent is a issue...

IT all depends upon HOW it dies
A dead stop will be electrical
A gradual stop with a bit of surging will be insufficient fuel from a partial blockage
This is why we ask questions like how does it stop ?

While it is nice of all of you to throw suggestions it is best to gather all the FACTS you need before trying to make a diagnosis and when a possibility is thrown at the poster, give them a test to confirm or revoke that possibility
Otherwise the poster ends up doing a whole lot of unnecessary things which may or may not make things worse or break things that that were not broken in the first place .

I tried to stay out of this thread because there were plenty of good willed people happy to help .
However we are 5 pages into the post and yet to do a DIAGNOSIS which is where you should be starting .

So the instant the mower stops the spark should be tested
I use an inline red test light for no other reason that they are easy to see in the daylight.
This does not confirm that the plug is firing but it rules in or out a failing coil .
The other diagnostic tool is a can of carb cleaner, if a short shot down the carb the instant the engine stops makes the engine fire and you can keep it running by repeating the process then that rules out the coil and rules in the fuel system.

I

 

[TobyU]

Sounds like valve clearance is too small. I adjust it .001" looser so it takes longer between adjusts.

Not on this or any Briggs OHV engines.
They do not wear tight like a valve in block engine.
They wear loose and they will always be really looser than specs when you check one that's not been adjusted in a while.
You should adjust these to the tight side of the specs .004 intake even tight .004 and .005 - .006 exhaust..
The intake needs to be tight so the ACR works as well as it can where the exhaust is safer when it's loose for cooling the hotter valve and on a 31xxxx or 33xxxx series eng the exhaust has no affect on acr or cranking.

 

[TobyU]

Quite true but not on a LA because they don't have one

IT all depends upon HOW it dies
A dead stop will be electrical
A gradual stop with a bit of surging will be insufficient fuel from a partial blockage
This is why we ask questions like how does it stop ?

While it is nice of all of you to throw suggestions it is best to gather all the FACTS you need before trying to make a diagnosis and when a possibility is thrown at the poster, give them a test to confirm or revoke that possibility
Otherwise the poster ends up doing a whole lot of unnecessary things which may or may not make things worse or break things that that were not broken in the first place .

I tried to stay out of this thread because there were plenty of good willed people happy to help .
However we are 5 pages into the post and yet to do a DIAGNOSIS which is where you should be starting .

So the instant the mower stops the spark should be tested
I use an inline red test light for no other reason that they are easy to see in the daylight.
This does not confirm that the plug is firing but it rules in or out a failing coil .
The other diagnostic tool is a can of carb cleaner, if a short shot down the carb the instant the engine stops makes the engine fire and you can keep it running by repeating the process then that rules out the coil and rules in the fuel system.

I

I agree. A lot of people who aren't techs just throwing out ideas or what they have had happen in the past.
That usually results in throwing parts at it and it's bad practice.

Wait until it dies and instantly check for spark. If no spark 95% chance it's a coil and don't buy from local dealer unless you want to pay a lot. Online aftermarket ones are fine and cheap.
The other 5% are chewed wires grounding out (just had a snowblower tonight like this) or kill switch messed up and in "kill" mode all the time.

 

[skiman]

Does a John deer even have a magneto? Does it fly? As others said it’s probably your coil an easy quick check with a $5 spark check tool. Someone mentioned putting a meter on it to check ohm but you might not get a bad reading with an intermittent coil issue. Start simple, obvious, easy and cheap.

ive checked literally hundreds of coils this way over time...if it reads between 2.5K and 5k ohms...its good...outside this range is bad...worked every time...outside the lower and upper limits has identified if the coil is bad every time without exception...been doing this for almost 50 years...

 

[bertsmobile1]

Modern magneto coils have a timing chip inside since around 1990 when Atom Industries patient ran out
You can not test the primary coils because the chip is in the way
It works for car coils,
It works for coils that have points
It does not work for coils that have embeded chips
As coils ( called armatures when the embed a 10¢ the charge $ 50 ) are not repairable the only test worth doing is to remove the kill wire to ensure the coil is the problem & not the stop switch or any safety switch .
This is a forum for serious repairs not for spreading old wives tales & urban myths, that is what Face book & twitter is for .

 

[pay1920]

John Deere LA 115 19.5 briggs and stratton starts cold runs 5 minutes and cuts off. loses spark. Has a new spark plug new gas filter, new air filter. Anyone else have this problem?

I had a mower do this one time, the gas tank had some bugs and rubber from the gas cap, blocking the gas flow to the carb. I removed the tank, cleaned it out and it's been running since.

 

[TobyU]

Modern magneto coils have a timing chip inside since around 1990 when Atom Industries patient ran out
You can not test the primary coils because the chip is in the way
It works for car coils,
It works for coils that have points
It does not work for coils that have embeded chips
As coils ( called armatures when the embed a 10¢ the charge $ 50 ) are not repairable the only test worth doing is to remove the kill wire to ensure the coil is the problem & not the stop switch or any safety switch .
This is a forum for serious repairs not for spreading old wives tales & urban myths, that is what Face book & twitter is for .

Absolutely true! The problem is a lot of people on here think they're one or even 50 experiences from 1965 to 19 91 are indicative of everything that exists in the world today.
There is really no such thing as a good or bad coil from one test!
Even one, even old school one, that testified can easily break down in 10 to 15 minutes and do what so many coils do and then be fine once they cool off again..
There are even coils, even on small weed eater style engines that can mess up and the internal timing gets screwed up. There was a recall that Stihl had on this for they would start and run but wouldn't run well at all or rev up to have the power they should..
Just a few years ago I saw a rash of the old Kohler command coils going out on the singles which were very prominent up until around 2003.
It was just the fact that these things were becoming 20 years old and all the years of heat, cracks and moisture etc was taking its toll.
They would have spark and would run a little bit or for a while but some wouldn't even start. When you watch them spark or on a test or whatever you would see that about every two and a half to three and a half hits they would be no spark.
In these cases you might get an ohm test that works okay but there are just too many times when something will check perfectly in a static test or at a cool temperature but in actual use will break down quickly.
So there's really little point in troubleshooting that way. Get it to mess up and diagnose it then.