Briggs And Stratton won't idle and Surges

itsjoeyboyJuly 23, 2008

If someone could please help me I'd appreciate it ..

I have a relatively new Brigs and Stratton 3.5 hp

Trimmer motor that won't idle and surges when the throttle is set up .. It just won't run smooth !!

1. It has a new spark plug

2. I went through the carb .. disassembling it.. cleaning it.. and replacing all gaskets and the diaphram.

It seems to be running a lil lean, but on this model the air mixture adjustment is covered with a brass cap.

Is this just a cover that can be removed ?? or is the air fuel mixture set at the factory ??

I don't know where to turn ...



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I'm guessing non -adjustable. You may get more replies w/ model and type # on the engine. There are several diaphragm carb styles to choose from.

    Bookmark   July 25, 2008 at 12:57AM
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Model 091202
type 1231E1
Code 040313YA

I noticed today when I disassembled the carb again that the flapper on the right ( leading into the tank ) doesn't seal. the hole in the carb body is too far forward and is slanted so that the flap can not seal. I'm wondering if it's time for a new carb .. and a request for reimbursement from B&S ...

If anyone knows if this is the way it should be ..let me know !! thanks !!

    Bookmark   July 25, 2008 at 2:14AM
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I suggest down loading the IPL from the Briggs website, so you will use the proper terminology, so we know exactly what you mean.

Are you talking about the diaphragm or the tank gasket.
Get a new diaphragm for $3-4. The tank gasket is just a gasket.

Blast carb cleaner through the 2 holes under the diaphragm to make sure both passages are clear.

    Bookmark   July 25, 2008 at 3:46PM
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I am talking about the diaphram and flappers on the side of the carb. I did get a new diaphram, and ran carb cleaner through every hole on the unit. but it seems like the the hole that goes from the flaper chamber ( next to the diaphram ) is clear, but too far forward for the flapper to seal over it. One hole leads into the diaphram chamber, and the other leads to the tank, which is the fuel pump. but the tank hole doesn't seem to be sealng ..
I'm just wondering if this is normal.


    Bookmark   July 25, 2008 at 9:48PM
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