When the engine is running, the pressure in the housing holds some air in the fuel in a mixture. When the engine stops, the air comes out of the fuel and goes to the top of the housing. The air goes out of the housing through hole (36) in the cover and into passages (37) and (38) in the filter base. The air goes under disc (2) through scratch (39) and down through passages (40), (41), (42). Then the air goes through the top of the filter housing and the remainder of the fuel stays in the housing and filter.
When the engine starts the next time, the fuel in the housing and in the filter will be the supply for the engine until the transfer pump pulls the fuel from the tank.
SIPHON BREAK HOUSING
36. Hole. 37. Passage. 41. Passage. 42. Passage
SIPHON BREAK FUEL FILTER BASE
2. Disc. 38. Passage. 39. Scratch. 40. Passage.