when i changed fuel filter i released all the pressure, amd the the fuel nozzle that is on the fuel pump itself, it has the fuel nozzel the nozzle in the middle and the return nozzel, when the pump activates no gas will go throught the pump sending unit, ive tried manually priming it , bringing the gas to the top of the pump, expecting to turn the keyand the pump to at least drizzle some out , but i cant get that either