it won't/can't stay full constantly because the check valve in the fuel pump will leak down as the motor cools and gravity is moving the gas to be more level with the the much lower gas tank supply.....that's totally normal....
(LOL, mount your gas tank on the roof and it will stay full)
compared to alot of pumps sold today your's is working excellent!!! (my check valve holds pressure for maybe 30 minutes)
all that a mech pump is.... is the rubber diaphram pushes/pulses a bit of gas past that one way check valve and spring combo and if the carb bowl is full so that the needle and seat are closed the line will build pressure...the check valve spring that limits/bypasses the gas at only 5.5psi isn't strong enough to hold the pressure forever....
Last edited by red65mustang; 07-26-2008 at 05:58 AM.