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I have a Yardworks 19 hp riding lawnmower with a intek Briggs & Stratton engine and it will run perfect fir about 15 - 25 minutes then it dies , and I check for spark and it has none so I change plug and it has spark and runs again for another 15-25 minutes then it dies again with no spark, and again I put new plug in and it runs again and then repeats , what do you guys figure is the problem could it be the coil ??? Thanks for any help you can give

Change the coil.

Sounds like a heat related deal. Have to be the coil or high tension lead failing I'd think.

Thanks guys I kinda figured it might be the coil I just never seen a coil kill plugs before I know they can heat up and stop putting out power but never kill a plug before, but thanks guys

Had a case of Champion plugs do that once. Each plug would run for about 5 minutes and then quit. Failed on multiple engines after installation on spring tune ups

Exactly. Just because it seems improbable doesn't mean it can't happen. When I was repairing office calculators I was having problem with a group of new machines adding wrong. THe OEM just insisting it is was impossible. Well with 100 machines doing it consistently they were wrong so set to find a set of repeatable miss-calc. It turned out to a simple set of numbers that always added wrong on those machines.

Boy was it fun to change out CPUs on nearly 200 machines just my area once they found the programming problem.

ILENGINE said:

Had a case of Champion plugs do that once. Each plug would run for about 5 minutes and then quit. Failed on multiple engines after installation on spring tune ups

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Back when champ first moved producrion to mexico there were problems with dead plugs out of the box. I never saw any. Supposedly the problem was fixed quickly and no more bad new plugs.

Hammermechanicman said:

Back when champ first moved producrion to mexico there were problems with dead plugs out of the box. I never saw any. Supposedly the problem was fixed quickly and no more bad new plugs.

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Have had a few random NGK plugs do the same thing but seem to be hit and miss. I remember reading years ago and haven't been able to find it since, but I believe that it was Champion said that a 25% misfire rate was acceptable. Which in todays equipment especially vehicles that misfire rate would set off the money light on most vehicles.

ILENGINE said:

Have had a few random NGK plugs do the same thing but seem to be hit and miss. I remember reading years ago and haven't been able to find it since, but I believe that it was Champion said that a 25% misfire rate was acceptable. Which in todays equipment especially vehicles that misfire rate would set off the money light on most vehicles.

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Hard to believe that a 25% misfire rate is acceptable. Back in the 90's when i was building 5hp briggs engines for WKA cart racing i got to attend a seminar (sales promotion) sponsored by champion spark plugs. Once you got past the sales hype and the engineer started talking it was worth the time. He explained in depth how ignitions worked and how spark plugs work. More to it than i thought. They gave us a copy of that years catalog. Still got it around here somewhere.

ILENGINE said:

Had a case of Champion plugs do that once. Each plug would run for about 5 minutes and then quit. Failed on multiple engines after installation on spring tune ups

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Glad you said that
Go a Kohler Confidant in the yard at the moment that keeps dropping a cylinder for a minute or so then runs fine for a few minuted before repeating .
Naturally no XC12YC's on hand at the moment so I will let it rest quietly for a day or so till they come in .

NGK plugs seem to resist fouling better than other brands.

Pittrotti said:

I have a Yardworks 19 hp riding lawnmower with a intek Briggs & Stratton engine and it will run perfect fir about 15 - 25 minutes then it dies , and I check for spark and it has none so I change plug and it has spark and runs again for another 15-25 minutes then it dies again with no spark, and again I put new plug in and it runs again and then repeats , what do you guys figure is the problem could it be the coil ??? Thanks for any help you can give

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If you’re not the original owner, Have you verified the correct spark plug is being used? Meaning not just replacing it with what was already in there, but looking up the correct plug in the manual (or on the B&S website)? It might be that the plug in it is the wrong heat range which could also be killing the plugs.