Fuel
Systems
Equipment Standards
FEDERAL LAW
183.526 - Carburetors
(b) Each carburetor must not leak more
than five cubic centimeters of fuel in 30 seconds when:
(1) The float valve is open;
(2) The carburetor is at half throttle; and
(3) The engine is cranked without starting; or
(4) The fuel pump is delivering the maximum pressure
specified by its manufacturer.
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There are two leakage tests for carburetors
to satisfy the intent of 183.526(b). This test relates to
183.526(b)(1), (2), and (3).
This test is performed by the marine engine
manufacturer and the carburetor manufacturer. Additional information
and requirements for marine fuel metering devices may be found
in SAE J1223 Marine Carburetors and Throttle Body Injection.
Fuel injection is now prevalent in marine engines. The regulations
specifically addresses carburetors, as fuel injection was
not commonly available in the mid-1970s when the regulation
was written. This test is to confirm the integrity of the
fuel metering equipment and is conducted as follows:
- the float valve is free to operate normally
- the throttle is in the half open position.
Crank the engine without starting for 30 seconds.
During this period there shall be no more than 5 cc observed
gasoline flow coming from the carburetor fuel bowl, vent port
or any other place on the exterior of the carburetor. This
test includes only external flow, not fuel flowing down the
throat of a downdraft carburetor.
NOTE:
A complete copy of the United States Coast Guard Compliance
Test Procedures — Fuel System Standard Test Procedure,
is provided in Appendix A of
the Fuel Guide.
TO COMPLY WITH THE LAW
- With the float free and the throttle
half open, the carburetor will not leak more than
5 cc of fuel in 30 seconds while the fuel pump is
delivering fuel, at the engine cranking pressure.
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This is the second leakage test for carburetors
to satisfy the intent of 183.526(b). The test described on
this page relates to 183.526(b)(4).
This test is to confirm the integrity of the
float valve with a remote fuel pump and is conducted as follows:
- the float valve is free to operate normally
- the throttle is in the fully closed position.
Connect the fuel pump with the largest pressure
intended for use with the carburetor and run it for 30 seconds.
During this period there shall be no more than 5 cc observed
gasoline flow coming from the carburetor fuel bowl, vent port
or any other place on the exterior of the carburetor. This
test includes only external flow, not fuel flowing down the
throat of a
downdraft carburetor.
NOTE:
A complete copy of the United States Coast Guard Compliance
Test Procedures — Fuel System Standard Test Procedure,
is provided in appendix A of
the Fuel guide.
TO COMPLY WITH THE LAW
- With the float valve open and the throttle
half open, the carburetor will not leak more than
5 cc of fuel in 30 seconds while the engine is cranked
without starting.
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