1 - pump should pull fuel until the tank is virtually dry, 2 or more gallons should definitely be enough to work, if you have the original style sender/intake
yes the pump can pull fuel from a newly installed tank via previously dry lines
2 disconnect the line from the pump to the carb, aim it in a can and crank awhile, you should get flow, it does take awhile even when the running truck has run out of fuel and you dump a gas can worth into it .... alternatively, disconnect the pump inlet and using a rubber line, put it in a can of gas, it should suck that up fast and fill the carb and prove if the pump is OK
if by some chance there's an 'air lock' between the tank and pump, filling the carb bowl should keep it running long enough to get things flowing
Bill
