Briggs Stratton 4HP high idle speed

I found the message I pasted below on this group a few days ago. I had this exact same problem with the same motor (10A902) 4HP. after reading all the replies I went and replaced the diaphragm. The mower now has a steady idle but it is much much higher than it was before. The mower also seems to run twice as loud as it used to. What do I do to fix this problem.
Tim
CanadianCowboy
My briggs and Strattan mover was working fine up until I ran it dry using every drop of gas. The next time I used the mover it runs rough with RPM's going up and down but never stalling. Is there a block in the carberator from the garbage at the bottom of the tank ? Do I have to take it apart and clean ?
Any help would be appreciated !!
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snipped-for-privacy@att.net wrote:

...
Adjust idle screw.
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If he didn't change the screw before or after replacing the diaphragm, that's probably not the cause of a much-higher idle.
You might have a vacuum leak, where air is getting sucked into the engine around the gaskets. Make sure the gaskets are all seating properly and the screws are tightened correctly. "Real tight" isn't as important as tightening evenly the several screws that hold a diaphragm or gasket.
Good luck,s
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DaveC
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having dealt with gaskets in the past I was careful to tighten the screws evenly and not over tighten. Im stumped.

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tmt wrote:

Float level?
Throttle linkage?
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> On Jul 31, 1:21 pm, DaveC < snipped-for-privacy@bogusdomain.net> wrote:
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On Tue, 31 Jul 2007 06:45:02 -0700, snipped-for-privacy@att.net wrote:

As far as I know, no Briggs and Stratton 4HP made in the last decade or so has a carb with an idle adjustment screw. They use that el-cheapo and funky vacu-jet carb with the vibrating diaphragm that acts a a fuel pump. There is neither an idle adjustment or speed screw. These carbs also have no float or float level adjustment. In effect, the fuel tank IS the carburetor bowl.
Did you replace the external throttle springs correctly? Those engines run at a more or less fixed speed determined by the back spring pressure on the governor linkage. Some mowers have a "throttle" adjustment, either with a lever or a cable, that simply changes the spring pressure.
Doug
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