Cant get gas to carb in 1979 ski doo?

i have a 1979 ski doo olympique and when i start it the only way to keep it running is to keep primeing it. it cant get the fuel flowing by it self. i checked the fuel pump its fine cleaned the carb and thats good,dont know what it could be.Cant get gas to carb in 1979 ski doo?
check the fuel filter.

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