Fuel pump / starvation question

[zracer22]

My 2.0 16v has no top end in 4th and 5th gears. I have checked and rechecked everything. I can't find the problem. But I think I may have figured it out......

I'm not running the stock external fuel pump and assembly. Instead of the stock pump and housing, I am running a larger bosch pump from a Mercedes. Fuel pressure test result in 100 PSI running and 45-50 psi residual pressure. is it possible that the intank pump cant supply fuel to the main pump fast enough when under load at high rpms in 4th and 5th gears.? Should I put a fuel sump between the tank pump and the main pump?

Mark

[Lael Cleland]

I have used a chevy truck in tank pump as a prepump. there good to 50 psi, and easy to swap

cheeper than a pierburg oem pump also