craftsman 21hp briggs

alg · Aug 24, 2017

Have a Craftsman with a 21 hp Briggs.When it gets hot ,it dies.Will not restart until it cools off. Where should I look. ????

Al

MtMan · Aug 24, 2017

You might have carbon build up on your valve stems where they go through the guides. This is usually not a BS problem but some other air cooled engines it is a problem

tractorguy2 · Aug 24, 2017

Could be the coil. have you checked for spark after it dies?

alg · Aug 25, 2017

That's my next step,this problem just started yesterday. Will run it today and try to diagnose the problem.

Texasmark1 · Aug 25, 2017

V twin? If so with 2 "Magnetrons" one should at least carry the engine with no load at higher rpm than idle. Clip a timing light on the spark plug wires and check for fire.......Note. Mine was 40 years old and had quit working. Got on ebay and found a new one for about $20. Really works nice.

My experiences with that problem have either been "coil" related or vapor lock. Timing light will chase the dead coil while a shot of Sea Foam or starting fluid in the carb would chase vapor lock. Put in a new fuel filter lately?

alg · Aug 25, 2017

Fuel filter fairly new,checked for flow through it this morning, good steady stream. Ran it for almost two hours and it didn't cut out.????Might only happen with the wife. Operator error??!!!!

jeffcat · Aug 25, 2017

One more thing with these Vtwins. A partially sheard key will really screw them up. They will run very hot if that key is even slightly clipped. Had one where that wafffle washer was getting weak and would let the flywheel move. Put a new washer on. Runs perfect.

T.R.K. · Aug 25, 2017

you don't say what its mounted on.

Some things to check:
The last one with that problem it was a fuel cap not venting.

Most 21 hp have a fuel solenoid. When it quits, is there still power to the solenoid?

Did the rubber plunger come off the pin in the fuel solenoid? (I had one in the shop 3 times before we caught it doing this.)

If its a single cylinder, it could be the coil. So when it quits check for spark.

There is a remote possibility of a valve sticking, but they usually don't re-start until they are fixed.

It could also be something on the chassis of the mower killing the spark. I have seen on some Troybilts that the kill wire from the NO-MOW in reverse switch came off the switch on the shifter, and was grounding to the frame at odd times.

Texasmark1 · Aug 26, 2017

Might watch her mow. Maybe catch the "smoking gun".

Texasmark1 · Aug 27, 2017

BTDT. I too once chased a problem to a slightly sheared Woodruff on an engine.....single, about 5 hp as I recall. Amazing how that slight change in timing cold cause so many problems.

jeffcat · Aug 28, 2017

Just rattles your cage, don't it?? The machine got so hot it almost caught fire. Glad someone else had this happen !!

craftsman 21hp briggs

alg

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MtMan

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tractorguy2

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alg

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Texasmark1

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alg

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jeffcat

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T.R.K.

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Texasmark1

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Texasmark1

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jeffcat

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