Section 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.(c) Each updraft and horizontal draft carburetor must have a device that: (1) Collects and holds fuel that flows out of the carburetor venturi section toward the air intake;(2) Prevents collected fuel from being carried out of the carburetor assembly by the shock wave of a backfire or by reverse air flow; and(3) Returns collected fuel to the engine induction system after the engine starts,CGD 74-209, 42 FR 5950, Jan. 31, 1977, as amended by CGD 77-98, 42 FR 36253, July 14, 1977