Specifications

84
Primer Bulb Identification
Caution must be used when replacing carburetor primer bulbs. Using the wrong primer bulb could cause hard
starting and operating problems. Currently, Tecumseh uses five different carburetor mounted bulbs. To avoid
problems, use the Master Parts Manual for the correct application.
The primer bulbs offered feature two different shapes; derby and stepped (or hourglass).
The stepped primer bulb is used to force a charge of air
into the bowl through the atmospheric vent chamber.
The sealing surface (diag. 139), prevents air from going
back into the air filter while priming.
Series 12 Carburetor
A new carburetor, part #640350, has been released to
produce improved starting on our 5 to 7 horsepower
walk behind mower engines. The carburetor was
designed to eliminate human error from the priming
process. The Accu-Prime™ system consists of a spring
loaded plunger behind the primer bulb that will create
a full seal each time the bulb is depressed no matter
what angle it is depressed at. Testing has shown a 15%
improvement in average prime volume. The Series
12 carburetor body is similar to the Series 11, which
uses an extended run fuel well to aid in starting. The
exception is the primer area, which includes changes
to the body of the carburetor that do not allow the new
primer components to retro-fit older carburetors. The
primer assembly will be available as a kit to service the
carburetor under part #640351. This kit will include the
primer bulb, retaining ring, plunger and spring (diag.
140).
DERBY STYLE
STEPPED
INTERNALLY
VENTED
EXTERNALLY
VENTED
INTERNALLY
VENTED
EXTERNALLY
VENTED
Sealing Surface
Foam element on externally
vented bulbs are to prevent dirt
ingestion.
139
640350
640351
140
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