external fuel pressure regulator. setting pressure.

[dodgemaniac]

Tonight I installed a fass external fuel pressure regulator on the return side of my p pump.

I ran a -06 line from the outlet of the pump to the inlet of the fuel pressure regulator. I then have the outlet of the regulator plugged. The bottom port on the regulator (relief/ return port) is plumbed into the tee fitting that came with my lift pump. Also plumbed into the tee in the injector return and exits to the tank. I am running a fass 220gph lift pump that is internally regulated to 45 psi.

My problem is that I can't seem to adjust the pressure lower then 48 psi at idle. I can get it to drop to 44 psi when free revving it .Am I incorrect in thinking I should be able to drop the pressure down to any pressure at the regulator? I am able to adjust the pressure higher the 48 psi at idle but not less.

Do I have something plumbed wrong? Or is the only way to tune the regulator is by applying a load to the engine?

[khaoskustoms]

If I remember right with my fass system on my 4BT, I put a 7psi spring in the regulator on the fass pump. My regulator after the p-pump is set to a max of 80psi, and I added another regulator in the return on the fass pump which is boost referenced and starts at 25psi with no boost and will increase to a max of 80psi limited by the regulator on the p-pump. It is a bit of a complex system but it was the only way I could get the pressure to vary while still maintaining lots of fuel flow through the pump for cooling.


Sent from my iPhone using Tapatalk

[tornado112]

I could be wrong but I dont think you have a problem. The FASS internal pump springs are regulating your system to a base of 45psi.

Why do you want to take the pressure down at Idle?. From what I know most guys tell you to add psi to the system not remove psi?

[cumminsman315]

It will not go lower than you have now without regulating on the feed side of the pump.

[dodgemaniac]

It seems that the return line I was using was limiting flow enough that I couldn't adjust the pressure properly. I ended up running a seperate dedicated return line from the regulator strait to the tank. After doing so I can adjust the pressure down as low as 10psi at idle.

[Kick Start]

Originally Posted by dodgemaniac

It seems that the return line I was using was limiting flow enough that I couldn't adjust the pressure properly. I ended up running a seperate dedicated return line from the regulator strait to the tank. After doing so I can adjust the pressure down as low as 10psi at idle.

Why would you want that?

[dodgemaniac]

Originally Posted by Kick Start

Why would you want that?

I set it at 48 psi after adding the new return line. I mentioned that I could adjust it down to 10 psi not because I would want it there, but because it will now bypass enough fuel to allow me to adjust the pressure. Before adding the new line I could not adjust it , which I believe to be from too much restriction in the old return.