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Simplicity Coronet 12 stalls when hot


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#1 dmauder OFFLINE  

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Posted August 26, 2010 - 10:24 AM

Hi All:

Brand new here. I found the forum while Googling for a stalling issue on a used Coronet 12 I recently picked up. It has a 12.5HP Briggs & Straton engine which seems to run great and starts almost on the first try every time. However, after running for 10-15 minutes and getting nice & hot, the engine just sputters out and dies. After I bought it, I replaced the spark plug, fuel filter, changed the oil, and checked the air filter (clean).

At first, I thought it might have been the safety switch under the seat not making good contact. It seemed like if I bounced a little on the seat while trying to re-start after a stall, it would fire up. So, I used some good ol' trusty duct tape and a small metal disk to permanently depress the safety switch. :) Unfortunately, that did not resolve the issue either.

So, any ideas? What would cause this thing to run fine until it gets hot and then stall? If I let it sit and cool for a bit, it will fire right back up and mow fine until it gets hot again.

Figured I'd get some ideas here before I haul it into my local Simplicity dealer for service.

Thanks!

Dave

#2 mjodrey OFFLINE  

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Posted August 26, 2010 - 10:44 AM

Dave:welcometogttalk:glad to have you here.

#3 MH81 ONLINE  

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Posted August 26, 2010 - 11:47 AM

After running for 10-15 minutes and getting nice & hot, the engine just sputters out and dies. After I bought it, I replaced the spark plug, fuel filter, changed the oil, and checked the air filter (clean).

What would cause this thing to run fine until it gets hot and then stall? If I let it sit and cool for a bit, it will fire right back up and mow fine until it gets hot again. Dave



I had the same problem with a TORO built Lawn Boy. Mine would sputter a while then die out. Problem ended up being sticking valves due to shellac. Clean the valve shafts, clean the guides (I carefully hand-ran the right size drillbit down the guides. ) and try it again, couple hours & a couple gaskets. Might just do it. Or, if not comfortable with all that, the dealer is always an option...

If that fixes it, run some 2-cycle mix once in a while to keep it from happening again.

It might also be a bad coil... Anyone else?

#4 Bolens 1000 OFFLINE  

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Posted August 26, 2010 - 03:17 PM

Could be a few things....

Bad Coil....

Is your fuel line next to an extreme heat source? The fuel could be vaporizing in the line....

#5 Bill56 OFFLINE  

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Posted August 26, 2010 - 10:25 PM

Welcome to GTtalk, Dave. Could you post some pictures of the Coronet?

#6 tractormike OFFLINE  

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Posted August 27, 2010 - 07:59 AM

Welcome to the forum Dave! Another thing you could check would to make sure that you don't have a mouse nest under the tin shroud covering the engine cooling fins. That could cause the engine to overheat also. The Valves sticking could be causing your problem also. I have seen it happen in the old Kohler engines. They would usually run 20 plus minutes and then stop. Let them sit a half hour and they would start up and go another 10 to 15 minutes and stop again.
Good luck on finding your problem and glad to have you here as a member!

#7 jdslednut ONLINE  

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Posted August 27, 2010 - 05:37 PM

Could you have a plugged vent in your gas cap? Pull off your cap and run it to see if she goes any longer.

#8 olcowhand ONLINE  

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Posted August 28, 2010 - 02:01 PM

So you've checked for spark as soon as it dies? If the spark is gone, then I'd say the coil is breaking down & you need to replace it. If spark IS there & choke helps, then likely a fuel delivery issue...as said, look at gas cap vent, etc. If choke does not help, then valve issue likely.

#9 dmauder OFFLINE  

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Posted September 10, 2010 - 08:25 AM

Hi All!

I just wanted to say THANK YOU to everyone for all the great suggestions -- all input is very appreciated! I'm going to check the air vent in the gas cap and check for anything under the heat shroud. Beyond that, I think I'll be taking it into my local dealer for some repair work. I'm not about to tear the engine apart because I'd probably never get it back together. :)

Dave

#10 cwsittko OFFLINE  

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Posted July 28, 2011 - 12:11 PM

Dave, I have the same problem, if you find out please email me, thanks in advance...Curt
cws56501@yahoo.com




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