The REAL Bosch 044 isn't E85 safe so it doesn't last long and there's are tons of fakes, counterfeits and low quality copies. Noone I tune uses it anymore. The Walbro 450s are a significant upgrade but its an in-take pump.
For any external pump, you need to keep the pump's inlet BELOW the lowest part of the tank. Besides that, just be sure not to restrict its INLET with a too small of a filter.
Thanks. I'm using the AEM 400lph that is E85/E90 compatible. Removed the after pump filter element and I'm still dropping pressure. I'm stumped. Maybe my Aeromotive boost ref regulator? I'll try a diff battery also.