4-23
EVAPORATIVE EMISSIONS CONTROL
CALIFORNIA MODELS
GENERAL
Buell motorcycles sold in the state of California are equipped
with an evaporative (EVAP) emissions control system. The
EVAP system prevents fuel hydrocarbon vapors from escap-
ing into the atmosphere and is designed to meet the Califor-
nia Air Resource Board (CARB) regulations in effect at the
time of manufacture.
The EVAP functions in the following manner:
●
See Figure 4-24. Hydrocarbon vapors in the fuel tank are
directed through the vent valve and stored in the carbon
canister. If the vehicle is tipped at an abnormal angle, the
vent valve closes to prevent liquid gasoline from leaking
out of the fuel tank through the vapor vent hose.
●
See Figure 4-25. When the engine is running, carburetor
venturi negative pressure (vacuum) slowly draws off the
hydrocarbon vapors from the carbon canister through the
vent hose. These vapors pass through the carburetor and
are burned as part of normal combustion in the engine.
The large diameter canister-to-air cleaner hose (canister
clean air inlet hose) supplies the canister with fresh air
from the air cleaner.
TROUBLESHOOTING
1
WARNING
Verify that the evaporative emissions vent hoses do not
contact hot exhaust or engine parts. The hoses contain
flammable vapors that can be ignited if damaged, thereby
resulting in personal injury.
The system has been designed to operate with a minimum of
maintenance. Check that all hoses are properly routed and
connected and are not pinched or kinked.
Figure 4-24. Vent Valve Operation
Figure 4-25. Carbon Canister
VEHICLE UPRIGHT
Hydrocarbon vapors
released to canister
through vent valve
VEHICLE TIPPED
Check balls stop liquid
gasoline from escaping
fuel tank
Vapors to canister
Vent valve and
check balls
Gasoline
Captured
check ball
b0258a4x
2
5753
1
3
1. Overflow vent hose from fuel tank
2. Vent hose to carburetor
3. Fresh air inlet from air cleaner backplate
4. Cable strap around all three hoses
4
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