Originally Posted by bmw335iguy
Interesting- so here's something I found yesterday
Cold start the car pegs 87-90PSI like a rock, does not budge no matter what.
But on a warm start (ie after filling gas or something) the car starts at more like 75-80PSI, and stays there until I drive around for a block or two. Maybe it's a matter of the pumps just needing to re-prime after losing some pressure with the car off for a few mins. IDK what to make of it.
I'm going to make some modest scalar adjustments this AM and see if that does anything. Perhaps I just got a crap 455 pump, it happens. SteveAZ was kind enough to ship me out his inline setup, so if this doesn't work a really nice alternative will be here soon.
I'll continue to bump this thread with updates, I think it could be useful for others experiencing problems with additional fuel pumps. Thanks for the help all involved, really appreciate it. "