On Tue, 31 Jul 2007 06:45:02 -0700, wrote:

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


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