I have the Lonnies dual pump system installed and when I originally was talking to Lonnie about it, we discussed the system as constant pressure and the hobbs switch to kick the 2nd pump on. The system was shipped directly to my installer and it was installed and setup as a boost reference system. I talked with Lonnie, and discussed the current boost reference setup and he said that is fine, but to ensure only positive pressure is hooked to the FPR, otherwise when the regulator sees vacuum it will reduce the fuel pressure and the fuel transfer setup requires around a 53-55 minimum pressure to function properly. Otherwise, it could suck only from the pump side of the tank and run out of gas, even though the other side of the tank is not empty.
But there is no way to get positive only pressure to the regulator with the Maggie. The base fuel pressure was set at 60-61, so when at idle, pulling 7psi vacuum fuel pressure will drop to 53-54psi, and under cruise I have seen vacuum of up to 11psi, dropping fuel pressure down to 50.
So, I need to get back to my installer/tuner and either set this up for constant pressure or up the baseline pressure so to 65/66 so I don't fall too far down under high vacuum.
If I stick with the boost reference setup, at 6.5-7.0 psi of boost, and baseline fuel pressure of 66, do you see the 72+ rail fuel pressure being an issue with the Maggie fuel rails? I am going to try and contact someone from Magnason, but I can see them simply stating their rails are designed for GM spec fuel pressure of 58psi.
Or, should I go with a constant pressure setup? Either way will require a re-tune, so I just want to get some opinions before I take the car back.
Thanks for any input.