Fuel System And Carburetor
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Carburetor
The P25 series of engines uses the Walbro WT series carburetors, or a carburetor of similar design from another
manufacturer.
The main distinguishing features of this carburetor design are:
• It has a butterfly valve, not a rotary throttle valve.
• The primer bulb is mounted on the carburetor.
NOTE: The carburetors used on the P25 engines are adjusted to meet federal emissions standards on the
assembly line using tamper proof needle screws. EPA and CARB standards do not allow for adjusting
of these screws once the finished product leaves the manufacturer.
Troubleshooting the carburetor
Typically, troubleshooting the carburetor is the last step in the diagnostic process. The other factors are more
readily identified; spark vs. no spark, specific pressure readings on a compression gauge, or a visible blockage in the
muffler. Carburetor function is more subtle. While specific problems with a carburetor can be identified on tear-down,
identification of the carburetor as the location of the problem is usually done by process of elimination.
Treat the carburetor as part of a system. If damaged fuel lines or a blocked filter prevent the carburetor from get-
ting fuel, it will never work right.
To troubleshoot the carburetor:
1. Check the operation of the primer. When the bulb is
depressed and released, fuel should move through
the lines.
NOTE: This is a wet bulb primer. It draws fuel from the fuel
tank through the pump and diaphragm chambers
and pumps it back into the tank, purging the air
from the carburetor. The primer will not squirt fuel
into the throat of the carburetor as dry bulb primers
do.
2. Remove the air filter cover.
3. Remove the two screws in the air filter housing with a
T-25 torx driver. See Figure 5.11.
4. Disconnect the fuel lines. See Figure 5.12.
5. Disconnect the throttle cable from the carburetor.
Figure 5.11
Screws
Figure 5.12
Fuel lines
Throttle cable
For Parts Call 606-678-9623 or 606-561-4983
www.mymowerparts.com
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