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Was not sure where to post whether in John Deere or in Briggs. Admin please move if inappropriate here.
Mower starts and runs fine, for about 15 minutes and then dies and will not start. Let it sit awhile and then you can run another 10-15 minutes.
My thoughts: Overheating?
Power-washed and cleaned the engine but had no effect.
Is it a heating issue or something else and what can I do about it?
Thanx for any help and thoughts.

Sounds like a fuel supply issue start at the tank and work back to carb , filter - hoses- pump etc

I thought fuel too initially but ...
The fuel filter is readily visible. It is full of fuel. Disconnect line and fuel pump is working fine.

When it dies check to see if you have spark.

Sounds an ignition coil heat soaking and failing.

First remove the engine shroud and check for a mouse bed that might preventing air flow. Reassembly and test if it fail to start again check spark at the spark plug while it not starting. No spark means you need a new ignition coil or spark plug.

No mouse nest under cover as recently removed shroud to put in new starter. Coincidence? This issue started shoirtly after new starter (but not immediately). Will check for spark when dies.

Ahhh, Check for wires pinched behind the starter.

Gas cap vent plugged?

No wires pinched and gas cap vent not plugged.
Wont let me upload a video
It has something to do with it getting warm, It runs fine but then just shuts off.
It tries to start (or starts for a second or so) and then shuts off,
That is what is puzzling me - only when warmed up and gets worse the warmer it gets. In other words, when first shuts off, can restart and run maybe a minute, restart and maybe 30 seconds, eventually will start for a second and immediately shuts off. Let it cool and we start the whole cycle again.

Engine running and dying
Video above (maybe)

Didn't answer if you had spark when hot.

Freddie21 said:

Didn't answer if you had spark when hot.

Click to expand...

When you try to restart, it does fire, it just wont start until cooled. So I can guarantee there is spark. BUT, maybe it is failing?
Going to replace magneto as not know what else to do

Before dumping lots of parts, try spraying carb or brake cleaner into the carb when hot and see if it wants to start. If so, and you have eliminated a fuel issue, then it's probably carb related. If not, then I would think spark related. If you have not actually replaced the spark plug, then try that 1st.

Freddie21 said:

Before dumping lots of parts, try spraying carb or brake cleaner into the carb when hot and see if it wants to start. If so, and you have eliminated a fuel issue, then it's probably carb related. If not, then I would think spark related. If you have not actually replaced the spark plug, then try that 1st.

Click to expand...

It always tries to start. As I said, it will fire (combustion) as long as you have key turned to start and will even run for a second or so but then dies. It is definitely heat related. Fuel would not be affected by heat or maybe a failing magneto?
Not going to dump lots of parts but may be fed-up and dump the mower.

Sounds most likely like a coil failing.
The typical way they fail is they will get hot in about 12 to 15 minutes and it will just shut down like you turn the key off. It will not restart normally until it cools off for hours and will run the same amount of time again and you can do this every single day running for about 12 minutes. Sometimes you let them cool off 4 or 5 minutes they will fire back up and only run for a couple of minutes but not normally.
The way to test is to get it running and when it dies immediately pull out the spark plug and check for spark. If you have no spark then you likely have a bad coil.

N00bie said:

Was not sure where to post whether in John Deere or in Briggs. Admin please move if inappropriate here.
Mower starts and runs fine, for about 15 minutes and then dies and will not start. Let it sit awhile and then you can run another 10-15 minutes.
My thoughts: Overheating?
Power-washed and cleaned the engine but had no effect.
Is it a heating issue or something else and what can I do about it?
Thanx for any help and thoughts.

Click to expand...

I agree with the guys saying is the coil. Coils will start to fail and will start to cause problems by not supplying a good spark or no spark at all when they warm up. Run it until it dies then test your coil using a multimeter. Your looking for the same reading been the boot and the pick ups and the kill wire connection and the pick ups. Be sure it's good and warm first. If it's not it may still read right even if it's bad. You don't have to pull it to test. Just pull the boot off the plug and pull the kill wire from it's connection so you can excess the tab. So run it until it dies, have you plug boot pullers and your multimeter on you. As soon as it dies check the resistance between those two locations, the boot and pick ups, then the tab where the kill wire connects and the pick ups. If they read the same your coil is good. If they don't read the same then it's bad. But I would almost be willing to guarantee that's the issue. The coil is heating up and the spark is degraded.

Nothing gets ruled in or out till it has been tested
For instance a loose inlet valve seat could produce the same symptoms
A leaking manifold gasket can do the same
As can a leaking head gasket
So you start with the mechanical or with the fuel
For me I pop a SHORT shot of carb cleaner down the plug hole
Engine fires = spark is good
Next do the same down the carb
engine fires = valve timing is good so that suggests fuel and the last bit is the carb solenoid
You can do a quick & dirty test by holding it while turning the key on & off
Then it is off with the rocker cover and check the valve lash
I do this after the carb cleaner because most are lathered with silly cone which takes forever to get off & be replaced with a gasket .
After the valve lash is set I rotate the engine and watch the valves
They are the same, their position in the head is the same & the cam lift is the same , these can all be verified with a simple visual inspection

As this engine is not running the next check is the head gasket - valve seal - rings by doing a leak down test and using ones ears for where the whooshing air is coming from
If all of these test OK then you are left with the magneto
You can use one of those very expensive variable gap jobbies or just hold the spark plug ( using insulated pliers ) about 1/4" off the head while you crank the engine
A good magneto will cause the plug to spark between the electrodes and from the engine to the outside of the plug from 1/4" to 1/2" away from the head
Do this test kill wire on & kill wire off , if the wiring is good then it should be the same
Now if you suspect the magneto try the above test with engine stone cold and again with engine hot
The distance a spark throws should be almost the same hot or cold ( hot will be a little less but not much )
If you have a bit of 1/4" metal bar, you can shove it into the spark plug cap
With the lower resistance a good mag will throw a spark from 1/2" to 1" away from the head

Very rarely the plug cap will go bad but you can sort of test this by pushing the cap harder onto the HT lead or screwing it in 1 more turn
I find those caps with the full metal shield to be the worst .

Sounds like a lot but it is less than 1/2 hour

MikeStihl046 said:

I agree with the guys saying is the coil. Coils will start to fail and will start to cause problems by not supplying a good spark or no spark at all when they warm up. Run it until it dies then test your coil using a multimeter. Your looking for the same reading been the boot and the pick ups and the kill wire connection and the pick ups. Be sure it's good and warm first. If it's not it may still read right even if it's bad. You don't have to pull it to test. Just pull the boot off the plug and pull the kill wire from it's connection so you can excess the tab. So run it until it dies, have you plug boot pullers and your multimeter on you. As soon as it dies check the resistance between those two locations, the boot and pick ups, then the tab where the kill wire connects and the pick ups. If they read the same your coil is good. If they don't read the same then it's bad. But I would almost be willing to guarantee that's the issue. The coil is heating up and the spark is degraded.

Click to expand...

Yeah, I was convinced it had to be the coil (magneto) so I just replaced it. Made no difference
Might be time to junk the whole mower?