Question: 1981 mechanical fuel pump ???

[FactoryC3]

While working on my fuel system, I found that when I disconnected the fuel outlet (to carb) fitting at the pump, a large volume of fuel ran out until I plugged the line from the tank at the inlet side of the pump. Not just what was in carb line, but solid flow. Is this supposed to happen or should the diaphragm keep fuel from running through to the outlet?

 

[dougelam]

Sounds like the tank was pressurized too me
EVAP plugged maybe?

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[FactoryC3]

Not pressurized

Sounds like the tank was pressurized too me
EVAP plugged maybe?

Sent from my SM-N920P using Tapatalk

The tank was not pressurized...gravity flow.