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Subject: 6 HP Briggs won't start when hot.

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joe in wilkinson    Posted 08-21-2017 at 19:15:06 [URL] [DELETE]        [Reply] [Email]  
  • 6 HP Briggs won't start when hot.
  • Why go anywhere else with all of the brains right here. Craftsman 22" mower, 6 HP Briggs engine. Starts fine with one pull when cold. I mowed for 15 minutes. Shut it down. Tried to restart and no luck. Even squirted a few drops of 89 octane gas in the spark plug hole, and not one fire. Let it sit for a couple of hours. Same story. Starts right up and runs fine until I shut it off. I replaced the spark plug, set at .030" and also .020" gap; still no start. Gas cap tight and also loose, so that is not the problem.

    joe in wilkinson    Posted 08-22-2017 at 17:22:33 [URL] [DELETE]        [Reply] [Email]  
  • Re: 6 HP Briggs won't start when hot.
  • Not perfect, but much better than it was. Research on the web indicated these engines expand enough when hot that the valves do not always close tight. The exhaust valve was "crudded up", so I re-seated both valves and increased the clearance on the exhaust valve to .011. Seems to be starting much better now when it is hot. We will see if it lasts.

    Really appreciate all the interest. Dan, I don't know how to check the timing. Sometimes the crankshaft key shears a little. I didn't pursue this because it was running so well. It actually ran very good, it just didn't want to start when it was hot.

    I "think" the case is closed. This mower actually belongs to a neighbor. Just trying to help. Thanks again to all!!!!

    36 coupe    Posted 08-22-2017 at 17:05:59 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 6 HP Briggs won't start when hot.
  • Check compression when hot.The first test on no start is a squirt of gas frome a pump oiler.

    36 coupe    Posted 08-22-2017 at 17:04:36 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 6 HP Briggs won't start when hot.
  • Check compression when hot.The first test on no start is a squirt of gas frome a pump oiler.

    Farmer Dan    Posted 08-22-2017 at 11:38:35 [URL] [DELETE]        [Reply] [Email]  
  • Re: 6 HP Briggs won't start when hot.
  • any way to check the timing?

    Carson (NCAL)    Posted 08-21-2017 at 20:01:21 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 6 HP Briggs won't start when hot.
  • Did you look to see if you had spark when it would not start. Just pull the plug, lay the plug against the engine and then try to start it. You should see a spark jump across the open points on the spark plug

    If you don't have spark you might look at a replacement coil. I just put one in a 5 horse and the new coil assemblies no longer use points. They have a hall effect sensor that triggers the spark.

    joe in wilkinson    Posted 08-21-2017 at 21:13:46 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 6 HP Briggs won't start when hot.
  • Yep. I have an inline spark tester and it shows spark when cold and when hot. Bunch of things to try tomorrow. Compression before and after. Some say this engine has valve clearance problems when hot.

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