Well I just changed to a supra pump hoping it would fix my problem,

so my setup is
Supra pump -> 6an lines -> Aeromotive filter -> 6an Y-block -> primary rail and secondary rail in parrallel -> SX regulator set at 40 psi when engines running -> 6an return.
Fuel pump re-wired 13.8v at pump at idle.

now heres the deal, if I get the pump running when the motors not I get ruffly 60 psi at the regulator, then I kill the pump and it SHOULD hold at 25 psi per the SX regulator instructions, Well it drops to about 10, holds for 5 seconds and goes to 5, then drops the rest of the way down , Their are NO leaks in the lines, I have taken EVERY SINGLE AN FITTING OFF, Re-tightened and pressure checked! this is getting stupid, I can not for the life of me find a leak. Now when the cars running which it doesnt like to do for some reason (really hard to get started) fuel pressure holds at 40 psi, when I get on it it steadily drops off. now heres the funny bit. every so often it holds and bumps pressure all the way to 50 under boost. generally when the car has JUST been turned on and hasnt moved anywhere. once I get it moving I cant hit boost because fuel pressure cuts like ****.

 

i had almost same problem with my walbro on my s5. it was leaking the pressure at the pump to sending unit by that stupid black oring not sealing right.

 

black O-ring? I am beffudled.

 

ur using a s4 or s5 sending unit assembly?

 

Those regulators won't hold fuel pressure very long after the pump stops. Only a few seconds or so.

As engine vacuum increases, fuel pressure will decrease. You describe that your pressure increases and approaches 50 under boost...that sounds like expected behavior.

 

The issue is when the secondarys open it cant flow enough, Ive figured it out to be MASSIVE amounts of sediment in the tank, The sock came out completely brownish red and filled with rusty sediment, the filter had tons of rusty sediment stuck before the element. I dropped the tank and it looks like ****, now I need to figure out what to do about it.