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Posted to rec.crafts.metalworking
RoyJ
 
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Default OT Primer on a snowblower, how does it work?

The float controls the level of gas in the float bowl, most carbs have a
small air inlet to keep it from air locking. On the primer bulb models,
this air inlet is hooked to the primer bulb. When you squeeze the bulb
the air pressure forces the gas down in the float bowl, and up into the
main needle, dumps raw gas into the carb throat. As soon as you remove
the pressure, the float needle opens a bit to replace the gas that was
pushed out. Radically simple.

Roy wrote:
The primer button (bulb) on my 12 HP sears snow blower developed
a tear in it and the blower would only work while the fuel tank
was fairly full (3/4 or more) I replaced the primer assy and was
very much surprised to find out that all the button seemed to do
was to force air into a single line. To that point, I had
assumed that there would be an in line and an out line and the
button would force gas into the carb but of course the needle
valve in the carburetor bowl would prevent that, unless it were
open. So without wishing to tear all the covers off to find out
what goes where,, could someone provide me with some kind of a
word picture or link that describes how this primer assy, that
appears only to push air into a line, actually primes the carb.

Thanks