76 datsun 620

hi i have my 76 datsun 620 truck that been sitting for long time, and the motor run greatly!! but there one problem, i have to pour little gas in my carb to get the motor start and rev it to keep it alive. when i pump my gas pedal, the gas does come out where the hose connect to carb. once i get let go the gas, it will die. i have already check all hose and install new feul filter. do i need to clean the carb?? i couldnt figure out the problem. so any help would be grateful!!!


-randall