governor problem

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  #1  
Old 05-26-04, 07:20 PM
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governor problem

OK, here's the problem, at school I am working on a snapper push mower with a briggs quantum 5 hp engine. The problem is that the engine will idle for 2 or 3 seconds then kill, plus it won't go any faster than idle. I cleaned the air filter but left it off, cleaned the fuel filter and carburetor. Then I found out that the problem is that the governor will keep forcing the butterfly valve back to idle. You can push the throttle to wide open and all the linkages move, but the governor keeps that butterfly valve closed. If I push the butterfly valve to wide open, then engine runs great, but that governor keeps putting pressure to close it. The governor spring hooked to the throttle linkage doesn't even pull on the butterfly valve since the governor isn't pulling on the spring. I will remove the shroud tomorrow, but I have no clue what would cause these problems. With the engine shut down, I can move the butterfly valve back and forth, it moves completely freely. Could the air vane be stuck in the overspeeding position? Thanks for the advice!!!!!!!
 
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Old 05-26-04, 09:00 PM
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If it's an air vane type governor it could be stuck. A lot of B&S engines have the fly ball type governors that are turned via gears and are located inside the crankcase. You can tell if they are free by seeing if the governor shaft will turn when the engine is off.
 
  #3  
Old 05-27-04, 12:12 AM
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I think that engine has an internal governor (quantum). Is there any evidence that someone has removed the governor lever from the shaft? Look for wrench marks on the governor arm clamp nut.
 
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Old 05-27-04, 06:54 PM
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OK. I took a look at it today and the butterfly valve doesn't move at all no matter how you move the throttle. There is a spring that connects the throttle linkage to the governor linkage and that spring never tightens or loosens, it just stays in one location causing the butterfly valve to never go to any position above idle. I have no clue how this setup works since the throttle won't even tighten up on the spring. Am I missing something here? Can someone please explain to me how this setup and linkages work? By the way, I broke the spring trying to adjust the tention, can I just stretch that spring and make it work? That spring is so long that it won't move the governor linkage it's hooked to. Also, the throttle linkage that the throttle cable hooks to turns like it should, but the spot that the spring hooks to is located in the center on that part and so even if it turns, the spring will not tighen up at all. Also, this engine does not have an air vane governor. I hope I explained everything clearly enough. Thanks for the advice!!!!!!!
 
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Old 05-27-04, 11:44 PM
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With the engine off the governor linkage should have a small radius of travel. The throttle cable should not directly move the throttle plate but instead simply adjust the tension of the governor spring. You should find the throttle at full with the engine off. After the engine starts, and as it picks up speed, the governor should start to move the throttle plate in the carburator towards a more closed off position to keep the engine from overspeeding. I think Cheese was trying to imply that someone was messing with the position of the governor arm on the governor shaft. From your description of the problem it would be easy for me to agree with Cheese on that point.

I wouldn't expect that there would be a change in the position of the throttle plate inside the carburator by moving the hand throttle with the engine off. You SHOULD see a change in the tension of a spring attached to the governor arm when you move the hand throttle. Your description of the problem implies that there is a disconnect between the hand throttle and the governor spring, or perhaps the governor spring itself is missing. The function of the governor is to slow the engine down. The function of the governor spring is the speed the engine up. The system was designed so that there is a constant "tug-of-war" going on between the governor and the governor spring each trying to control the speed of the engine. Your hand throttle can influence the outcome of this battle by making the pull of the governor spring stronger. This stronger spring pull will open the carb throttle plate. This will make the engine speed up. At a new higher speed the centrifugal force generated by the governor flyweights will again be able to balance the higher governor spring force and the battle for engine speed continues as a stalemate at the higher engine speed.
 
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Old 05-28-04, 12:54 AM
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I didn't see any obvious signs of the governor be tampered with. With the engine off and the governor spring removed, the throttle plate does have a little amount of springyness to make it close. But as I said, the governor spring is so long that it doesn't pull the governor linkage at all. So let me get this right, with the engine off, the throttle plate should be in the full throttle position? If that is true, then the governor spring is way too long. One other question still remains, I am sure this mower worked correctly at one time, so why would it start acting up? Did I overlook something more obvious? Surely the governor spring didn't grow overnight. HELP!!!!!!!
 
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Old 05-28-04, 12:59 AM
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Do you know the history on it? I mean, did it just quit working and they brough it to you, or maybe did someone try to fix it, or did someone remove the carb and possilby the linkages fell off and they got installed incorrectly? It doesn't sound like this is put together right. I'll look at the shop and take note of the governor linkage on one of these engines, and let you know what I see. Maybe I can describe it to you and you can compare to see if yours is installed correctly.
 
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Old 05-28-04, 01:03 AM
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I will try to find out tommow on the history of the problem. All I was told is that it would only idle. I would appretiate it if you could check out the linkages cause they just didn't look right to me.
 
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Old 05-28-04, 12:16 PM
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You are correct, mower17, with the engine off the throttle plate should be in the full open position. I usually try to adjust the governor arm on the governor shaft so that, yes, the throttle plate is full open, but there isn't much spring tension from the governor spring holding it there. This adjustment is made with the hand throttle in the slow speed position. This way when the engine starts it takes a minimum of force from the governor flyweights to overcome the spring force to start closing the throttle plates from the full open position. I think I've seen a spec for the amount of spring tension in one of the B&S manuals, but that's a lot of trouble trying to actually set the governor spring in this manner. I usually just try to "wing it" and am usually close on the first or second try.

I does sound like someones been messing with the governor spring, or throttle linkages on the machine you're working on. Governors are very reliable and you won't have much trouble with them if they are left alone.
 
  #10  
Old 05-28-04, 04:14 PM
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Well, I finally fixed it today. I kept bending the governor spring to shorten it and I slightly bent the throttle linkage to stretch the spring at the right time. I kept messing with it for a couple of hours and finally it revs up and idles just like it should. The governor spring was way to long to do anything, that is why it wouldn't speed up. My teacher said that nobody messed with it and this problem showed up all of a sudden. How that governor spring grew at least half an inch, I have no idea. I also pulled a hand full of grass out the air cleaner and sharpened the blade, which had deep chunks broke off of the cutting edge. It's strange how when someone's push mower breaks, the gas trimmers and riding mower is never far behind!!!!!!!!! Thanks for everyone's help!!!!!!!!!!!
 
  #11  
Old 05-29-04, 08:41 AM
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Glad you got it fixed. I usually don't believe it when someone says "it just broke and I didn't do anything to it".
 
  #12  
Old 05-31-04, 11:51 AM
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Good job! Maybe the owner was pushing the mower under some shrubs. I have seen linkages and springs get bent, stretched, and disconnected because of low branches that snag on the mower.
 
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