Briggs and Stratton 104M02-0010-F1 starts 1st pull runs and mows perfectly about 15 minutes and dies. Won’t restart until next day. Please help

[Phillip Campbell]

My wife bought this Toro mower used. As stated above, it starts first pull, runs, and mows perfectly for about 15 minutes then just dies. It sounds like the motor slows down right before it dies. The next day same story. Starts runs about 15 minutes and quits. I have cleaned out the carburetor and fuel tank. Changed the spark plug. Blown out the air filter. I have read that you can’t really get good readings on the coil with an ohmmeter, but for info purposes mine reads 9.70.
Thank you
Phillip

 

[Rivets]

Next time it happens check to see if you have spark. Sounds to me like you have a hot short or hot open, which would indicate a bad coil.

 

[Phillip Campbell]

Will do. Thank you

 

[dspikes]

One thing to try is loosening the gas cap. At times, the breathe hole gets clogged, and once enough fuel is used, a vacuum is created, and the fuel won't flow. Just a random thought.....

 

[sgkent]

someone here has recommended a spark tester from HF. That is one way you could see if you have spark. I know of 3 issues that are heat related - bad coil, tight valves / loose head, and fuel starvation if the tank can't breathe.

Bad coil - test for spark
Tight valves or loose head - check compression before and when it happens to compare
Tank not breathing - loosen the cap and try again.

 

[slomo]

Those inline spark testers are a waste of money. Yes you will see a light flicker if you have spark, but.......

Coils need to be LOAD tested. As in this tool or something like it.

 

[Rivets]

Sorry Slomo, but you and I disagree on this one. Been using the inline neon light tester since the mid 70’s and I’ve never had a problem. I’m probably on my 5th or 6th one. I don’t remember ever needing to know the sparks strength, just if the system is sending enough current to jump the gap when the plug is in the cylinder.

 

[sgkent]

the only time an inline tester would not be accurate would be if the plug was grounded internally, tip crushed, carbon across the gap etc.. If the spark jumps the gap that is enough to know there is spark. The gap and compression in the engine determine the actual firing voltage of the plug.

 

[Rivets]

Sgkent, I need to be clearer, testing a plug outside the cylinder can give you a false reading. I’ve used a tester on plugs without them being installed in the cylinder and they will fire. Once the plug is installed it may no longer jumped the gap. It’s happened to me more than once.

 

[slomo]

Sorry Slomo, but you and I disagree on this one. Been using the inline neon light tester since the mid 70’s and I’ve never had a problem. I’m probably on my 5th or 6th one. I don’t remember ever needing to know the sparks strength, just if the system is sending enough current to jump the gap when the plug is in the cylinder.

WIth the PET-4000, you see the actual spark and know if the coil is strong enough for combustion. You guys only see half of the puzzle.