I installed a new gas tank and sending unit and I can't fill the tank without it spraying gasoline out of the filler - this happens when the tank is mostly empty. The first time this happened, I soaked my shoes. (I stand back now). Once it gets to be 1/2 to 3/4 full, the problem stops. Very slow filling is required or it sprays gasoline back out the filler. I have the return line connected and the vent line is connected to the filler up near the cap. The filler hose is new and all hose connections to the tank are new. Thanks in advance for your help.