15 HP B&S is running at top speed

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  #1  
Old 05-03-10, 07:20 AM
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15 HP B&S is running at top speed

I have a 15 HP OHV Briggs & Stratton (28N707-0162-01). About two weeks ago it suddenly raced at full speed and before I could shut it off it bent a valve and a push rod. I have repaired the engine and it now runs again but I cannot let it run more than a couple seconds because the engine wants to run at maximum speed. I have checked the governor and all the linkage. It all seems fine. There is a lever that goes into the engine (connected to the governor) and I think it has something to do with the governor but I would have to take the entire engine apart to get to it and I donít know what it does. Could that be the problem? I need some help to get it running correctly.

Thank You
 
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Old 05-03-10, 08:17 AM
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Check the butterfly valve in the carb, see if it has jammed wide open in the throat. Possibly the mounting screws have loosened or throttle shaft broke or....
 
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Old 05-03-10, 08:28 AM
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Originally Posted by BFHFixit View Post
Check the butterfly valve in the carb, see if it has jammed wide open in the throat. Possibly the mounting screws have loosened or throttle shaft broke or....
Also check the screws that hold the butterfly on the shaft. They have been known to loosen and fall out.
 
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Old 05-03-10, 09:11 AM
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Originally Posted by indypower1 View Post
Also check the screws that hold the butterfly on the shaft. They have been known to loosen and fall out.
Those are the "mounting" screws I was referring to
 
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Old 05-03-10, 02:37 PM
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Checked

I have checked everything and its fine. Both the choke (which is near the outside of the carb) and the butterfly (which is a little further in ) are working great. I really am at a lost.....
 
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Old 05-03-10, 06:59 PM
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Originally Posted by FireChief105 View Post
I have a 15 HP OHV Briggs & Stratton (28N707-0162-01). About two weeks ago it suddenly raced at full speed and before I could shut it off it bent a valve and a push rod. I have repaired the engine and it now runs again but I cannot let it run more than a couple seconds because the engine wants to run at maximum speed. I have checked the governor and all the linkage. It all seems fine. There is a lever that goes into the engine (connected to the governor) and I think it has something to do with the governor but I would have to take the entire engine apart to get to it and I donít know what it does. Could that be the problem? I need some help to get it running correctly.

Thank You
That rod going into the engine has a flat end that goes against the oil slinger/governor combined. The slinger has plastic teeth that engage with the cam teeth which spin it. When it spins there are weights that open and push a piece out to push that rod you mention which in turn moves the exterior lever attached to throttle to slow engine down. Sounds like you have a damaged slinger. You have to remove bottom of engine (crankcase cover aka sump) to check it. I had one recently and the hole on the tab that fits on cam end was worn oversize.
 
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Old 05-04-10, 06:53 AM
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Originally Posted by FireChief105 View Post
I have checked everything and its fine. Both the choke (which is near the outside of the carb) and the butterfly (which is a little further in ) are working great. I really am at a lost.....
You should be able to control engine RPM by manually moving the throttle valve, if so, it does sound as though you have an internal issue.
 
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Old 05-04-10, 09:09 AM
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Internal Issues

You you be kind enough to explain to me what kind of internal issues could be present or explain how the internal parts of the governor work ?

Thank you
Marty
 
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Old 05-04-10, 01:09 PM
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38racing...Thank you for the explanation

and is that a big job or can I just take off the oil pan?
 
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Old 05-04-10, 06:00 PM
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Originally Posted by FireChief105 View Post
You you be kind enough to explain to me what kind of internal issues could be present or explain how the internal parts of the governor work ?

Thank you
Marty
Much as 38racing explained, although there is no "oil pan" per say, it requires removing the sump from the engine block and examining the internals of the engine.

use the model and type you posted at this link Operator Manuals, Illustrated Parts Lists & Wiring Diagrams - Briggs & Stratton for manuals and illustrated parts list for reference.
 
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