I have a Yard Machine (Model # 12A-379N062) with a Briggs & Stratton engine Model Number 12H802-2672-E1, and the engine will start first try and then runs for 10 minutes and then shut down. Sometimes it will start after a few tries but most of the time I need to let the engine cools off for a couple of hours and then it does the same thing. The air filter and spark plug are new and gas is new from gas station. Any ideas? Thannks for any help.

 

Check for gas flow into the carb bowl. Also check spark after it dies. Let us know what you find.

 

Thanks cheese for the quick response!
How do I check the gas flow into the carb bowl?
Will check the spark when I get home this afternoon and respond.
Thanks again.

 

Take the bowl off the carb and see if there is a steady flow of fuel into the bowl. As soon as you take it off, it should start flowing, so be careful.

 

cheese
Thanks again - Should I check for flow after the engine dies or prior to starting up?

 

You can also try loosening the gas cap and see if that helps. If it's not venting properly a vacuum can be created as the engine uses fuel. Letting it sit until it cools possibly allows enough time for air to seep in and equalize the pressure so it's good for another 10 minute run.

Is the engine sputtering and slowly dying or when it's good and hot is it like you flipped a switch? If it's running fine and then just dies it could be the ignition coil failing when it gets hot.

 

Pilot Dane,
Still not home yet to try all the suggestions but to answer your question, the engine would sputter for about 15 to 30 seconds and then dies.

 

Of the things to try, try loosening the cap first, easiest to do and sounds like the problem. Have a good one. Geo

 

Thanks for all the suggestions and as promised, here is what happened
First, I removed the air filter and cleaned it with compressed air. Then I used the compressed air to blow out all the debris from the engine. I then unscrew the gas tank cap leaving about 2 threads engagement between the cap and the tank. I then started the mower (started on first try) and began my normal mowing and unscrewing the gas cap every 5 minutes and reinstall leaving about 2 threads engagement as stated above. The mower did not stalled for the entire mowing period which normally lasted for about 35 minutes.
I am not sure what did it and not sure if it will act up the next time I try to mow the lawn. With this input, can someone concluded what was or is my problem?

 

You need a new gas cap. Have a good one. Geo

 

Yep, I agree. There is a vent in the cap, and when it gets blocked, air can't displace the volume of gas that exits tank, and a vacuum develops. The gas flow gets too little for the engine to run.

 

Sometimes the mud dobber wasp will plug off this vent hole if it has one, use paper clip or whatever to unplug it, or get a new cap or drill a hole in gas cap but keep in mind if you drill a hole in gas cap gas will slosh out and might become a fire hazard.

 

This is a long shot, but have you checked the oil level?

My son has an older B&S powered lawn mower that died after a few minutes of running. After letting it cool down, it would start right back up and die again after a few minutes. The oil level was VERY LOW!

 

Update:
I ordered a new fuel Tank Cap but B&S sent the wrong part so I used the mower with the old cap for the second week in a row now with now problem. I keep opening the cap every 5 minutes or so to releive any pressure and it seems to work. I should get the new cap next week and will respond with the result. Thanks again for all the suggestions.

 

Doesn't the gas cap just have a small tiny hole on the top? Maybe a needle or toothpick would cure it?

 

Allpauwork, Some do some don't.

 

I have a crafsman 18.5 42" cut riding lawn mower,five years old, same thing, starts great, runs great, cuts great, for about ten minutes, then misses and quits. Have to wait 30 minutes and can start again, but the outcome will be the same. I need help, I have cleaned every thing, and checked everything I can think of, again, I NEED HELP !!

 

Did you read this thread? Did you try loosening your gas cap? Did it help?

 

gas cap has a small hole in the top of it for vent,

 

Is the hole open??? Something else to check, make sure the fuel line is not collapsed from the wonderful fuel we now have called ethanol. The line will collapse internally but look fine out side. Good luck. Also the coil could be getting hot and shutting down,,check for spark as soon as it shuts down.

 

More Update:
Briggs & Stratton sent me the wrong cap again so I had to use the mower as is this weekend. I did the same - Opening the cap every 4 or 5 minutes and let the tank breed for about 30 seconds and install back the cap. Worked for a second week.

 

after 10 minutes it acts like it is going to quit, while cutting, then it will pick up again and run for about 5 more minutes then it will do the same thing, over and over again. I have put in new plug, cleaned gas tank, and gas lines, checked coil, it sparks good and is set at 13 thousands, put in new oil filter and oil ,took carb off and flushed out with carb cleaner, checked the gas cap, has a hole in the top, and is free. cleaned up the entire engine(outside) and all over frame and mower panel.
What am I missing?
Thanks
Don
crimson9

 

Plug should be gapped at .030", not .013". Did you actually take the carb apart and clean out the jets?

 

plug gap is set at .030 --.013 is the proper setting for the coil gap. Yes took it apart and cleaned everything. Today I found the problem. The choke spring was broken and I replaced it. Now it runs fine.

 

I have found my problem.. the choke had a broke spring, replaced it and ir runs fine.

 

Update:
I think it is definitely the fuel Cap. I've replaced the cap and every thing seems fine now. Thanks to all for their suggestions.

 

I removed the black plastic piece from the pintle of the fuel shut off solenoid on the carb and the engine ran for hours after that. that black piece was loose enough to float up and shut off the fuel while running

 

Had the same issue. I fixed it in about 45 min. Has happend to me about 10 yrs ago with a different tractor. Make sure you have a good ground on the engine. Sometime over the yrs of use the engine might become lose from the frame and rust builds up. My engine was lose so I re-bolted it down. Works fine now. Would run for about 2- 3 min then stop. Then you could restart for another 2-3 min then it would stop.

Hope that helps

 

I just picked up a 2005 craftsman with BS 675 engine. I replaced the oil, spark plug and broken pull cord (air cleaner was pretty clean), but after the 1st few pulls the rope is a bit loose. It takes about 8 pulls to start and makes a lot of rattling noise - after about 10 min sputters and dies. Will not start right back up.
I'll replace gas cap tomorrow, but concerned about the rattling and slow start.
Thanks for you suggestions!

 

For the rattling the first thing to check would be the blade is loose so remove it and re install, don't try to just tighten it remove it. Have a good one. Geo

 

After viewing all types of websites, including Briggs & Stratton support, I was convinced that much of the advice assumed the worst and offered complicated steps to resolve. My 21 HP Briggs & Stratton would run for 5 minutes and then cut off as if you turned the switch off. No sputtering, just died. It is now healthy and happy and runs like a champ. Here were my steps to fix it:
1. Is it bad gas?: probably not a gas issue if it runs fine for 5 minutes and then just shuts off. Keep going
2. Is vent plugged on gas cap: Loosen a turn and then start. If it keeps running, Buy a new gas cap.
3. Maybe fuel line issue: replace fuel line with new line, replace fuel filter with new filter
4. Is it a spark issue?: Since you changed the fuel lines, go ahead and put in a new spark plug.
5. Why it cuts off when hot?: Buy a cheap $6.00 spark plug tester. When the motor cools, restart and let it run until to cuts off. Attach the spark plug tester and try to restart the motor while it is hot. If you are getting NO spark, you have solved the problem and at this point have only spent a few dollars for filter, line, spark plug and tester.

The problem is a bad ignition coil. Cost for my 21 hp was $40. It took a few minutes to install. There are multiple videos that show the simple steps. My mower started immediately and ran like a new mower. - GOOD LUCK, Bayleedog.

 

Bayleedog:

Curious as to how old your tractor (?) is. B&S has had that issue for years. I've seen it on more lawnmowers than anything else. Shouldn't point the finger at B&S though. I've had my share of hot coils opening up on Tecumseh engines too.

 

Mower is 8 years old. No issue with B & S engine. Only that the online tech was sure it could ONLY be vapor locked and if loosening the cap didn't work, the only solution was to take it to an authorized repair center.