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Thottle stuck wide open


waterdowg's Avatar
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11-08-04, 05:41 AM   #1  
Thottle stuck wide open

I have 8hp Briggs & Stratton on a Snapper Riding mower. Engine model numbers 19702 1188-01 80022909. The thottle lever does not move when I move the thottle control. It is in the wide open position. When I try to move it by had it won't move but if I push in a little on the Thottle lever on it moves free. It looks as thou it is being pulled a the wrong angle from the governor plate. Is there an adjustment for that lever or spacers? The engine runs fine and starts on the first pull everytime, but is the thottle is always wide open. The choke moves and opens fine.

 
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cheese's Avatar
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11-09-04, 12:35 AM   #2  
Hello waterdowg!

I'm not quite understanding your terminology. Is the throttle cable moving at the throttle control plate on the side of the engine? Can you disconnect the cable from the engine and manually control the throttle?


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11-09-04, 05:26 AM   #3  
Sorry Cheese its hard to explain. The thottle cable does not move the thottle open or closed. It does move the choke open and closeed. If I take the cable off and move the thottle from the thottle plate it will not move, but if I push the thottle lever on the carb in towards the carb it will move from the thottle plate. I don't know how to post pictures or I would do that.

 
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11-09-04, 09:19 AM   #4  
Azis
Is it possible the throttle valve itself is stuck? I have seen the shaft where the screw holes are to mount the throttle plate break, and the throttle valve wedge in the throat wide open. You should be able to use the choke as suito throttle if this is the case, or look in the throat of the carb and see if it is physically moving.
I was a bit confused also when I read this last night but thinking along the same lines as cheese, is the restriction is in the cable or at the carb, if you remove the cable and it operates normally, then the problem is at the carb either linkage or internal.

 
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11-09-04, 10:13 AM   #5  
All the throttle cable does is adjust the tension on the governor spring. It's the combination of forces of the governor spring & governor centrifugal force that actually moves the throttle plate in the carb. I can't visualize what's going on here and I can't imagine how the governor could get jammed so the throttle arm on the carb wouldn't move, but that's what sounds like is happening here. The governor spring tends to open the throttle and the governor itself tends to close the throttle. A jam in the linkages would tend to leave the system jammed in the wide open throttle condition. The governor is the only thing that will slow the engine down by closing the throttle. If that isn't happening, then either there is a mechanical jam in the linkages themselves, or the governor is broke and/or jammed.

 
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11-09-04, 11:26 AM   #6  
The the cable and the throttle plate move fine. I may be wrong as to what I was saying. I'm looking the Briggs & Stratton Illustrated Parts list from B&S web site. I think my problem is the choke valve. I was thinking that it was the thottle valve because when I move the thottle control to choke the valve above the bowl would snap open. Now seeing that I think I'm really confused. Here is the link to the Parts list from B&S if anyone is intrested in looking.
http://www.briggsandstratton.com/om/...6-Domestic.pdf

On page 3 there is a break down of the carburetor. Part #131 is the thottle that and 141 is the choke. Correct???
I will try to explain again what is happening hopefully I can do a better job.

When the engine is NOT running and I move that thottle control to choke the throttle valve (131) snaps open, when I move it back it snaps closed. So I seem to have either completely closed of open thottle.

Now for the part that doesn't move with the thottle control the choke (141). This will not move with the thottle control. But if I push on the choke shaft and lever I can move it by hand.

I haven't looked to see if this moves when the engine is running but my guess is that I doesn't and I'm running with the choke open. I will start the engine on Thursday and look to see what happens. I will keep you posted.
If anyone can understand what I'm talking about and has any information please let me know.

 
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11-09-04, 02:49 PM   #7  
Azis
Ok I think I do have a better pic, the link you put up tho was to the owners manual and I could not find the parts list other than to buy on CD rom on the briggs site.
With the engine not running the throttle valve will act as you just described, it will open full or close full. With the engine running, the govenor comes into play and with the springs and linkage should control throttle movement depending on engine rpm and throttle setting. So that sounds normal.
As for the choke, apparently to actuate the choke your throttle lever moves to the limit of travel for choke, then back a bit for full throttle/choke off. The way this operates is on the throttle valve shaft lever, there may be a pin or raised tang that when opened far enuff would contact and move the choke lever. The choke may have a small spring pin it ratchets on or be spring loaded to the open position.
It may be as simple as a cable adjustment, with the throttle lever moved to full travel (choke) loosen the clamp on the cable at the carb, see if moving it will actuate the choke, if so when the choke gets to its closed stop, tighten the clamp.
After just re-reading your posts, are your observations you are questioning when the engine is running or when it is not?
The engine runs fine and starts on the first pull everytime, but is the thottle is always wide open.
Are you having problems with how the mower is running or just have some questions as to how's and why's?
Either way is great just need to know if we need to fix somin or just splain it LOL

 
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11-09-04, 11:25 PM   #8  
On the carburetor, the throttle is the valve closest to the point where the carb attatches to the engine. The choke is closest to the end of the carb. It is pulled shut by a lever on the throttle control box on the side of the engine. It pulls a hook shaped linkage that is connected to the choke lever on the carb in the engine side of the carb. When the engine is running, can you slow it down by manually moving the throttle on the carb itself? Is the linkage from the governor arm connected to the throttle on the carb?


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11-10-04, 06:07 AM   #9  
Sorry here is the correct link to the parts list.
http://www.briggsandstratton.com/ipl...100/MS6926.pdf

When I move the thottle control it does not move the choke. When I look at the gov plate I can see were the choke linkage attaches. I can not move it there. But I can move it at the carb but only if I push in on the shaft. I'm pushinh the shaft in toward the carb as if I were to install it. It almost looks like it is pulling at the wrong angle. Is this possible are there different carb for these engines. It looks as if the carb may have been replaced at one time. The engine is white and the are is black. I just got it for free from my brother-in-law who had bought 2 of them cheap.
As for slowing down the engine no it is either full of it shuts off. I will start it tomorrow and see what happens when its running. I have to put the gas tank back on, as I have winterized it and thought that I would be able to fix it without having to start the engine. Thought it may be a cable or linkage.

 
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11-10-04, 04:30 PM   #10  
Azis
On page 3 there is a break down of the carburetor. Part #131 is the thottle that and 141 is the choke. Correct???
As for slowing down the engine no it is either full of it shuts off.
I still think you want to verify that when part# 131 snaps open and closed that part # 130 also moves with it. From the looks of your carb it may be hard to get a look at it if its the one I am thinking of, I have only seen one on a chipper and dont recall much. I cant tell exactly where the throttle plate (#130) actually installs, but unless it is between the air filter flange and the bowl, which would make no sense to me, its going to be a bit hard to get a look at it. You may be able to get a finger inside to feel if its moving or not.
It also looks like there is only one screw mounting the valve to the shaft.

 
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