do a fuel pressure test. looks like it could be a stock hipo pump but a pressure test is needed.
another thing to think about is adequate venting of the fuel tank. i did some tests on some pumps and an original hipo 440 pump pulled 19" of vacuum. in fact it pulled more vacuum than any pump i tested. if the fuel supply system isn't properly vented high vacuum in the lines can contribute to the fuel flashing.
My tank has lines going to the vent(s). Checked under there one day looking for a fuel leak. Saw they have newish rubber hoses on all the lines back there. When the tank is filled to the point of the deadman stopping the pump, I then can get an overflow out a vent, at least best I can tell.
This car appears to have multiple vents compared to what I remember on previous cars. Other ones I had ran the vent up into the frame rail and only had one best I can recall. This is a CA car and I’ve never had one before.
Maybe run the tank down and blow air through the vent lines?
