Fuel Pressure Safety Switch with Zex Wet Kit

[ukgtguy]

Anybody running a fuel pressure safety switch with a Zex wet nitrous kit ?

Looking for advice/recommendations on a suitable EFI compatable hobbs switch, pressure setting, and wiring.

In the absence of higher intelligence (or previous experience) I'm thinking :

- Datalog my fuel rail pressure with my Predator (guessing it's going to be 38-45 psi or thereabouts)

- Plumb the FPSS into the fuel tap to the Zex NMU, setting it to my min fuel rail pressure (less 5 or 10 psi)

- Wire the FPSS to interrupt either the ground to the NMU or the 5v signal from the TPOS sensor.

I really would like a safeguard against my pump failing, but I've read bad things about hobbs switches cutting out or 'fluttering' the system when improperly installed or adjusted

 

[BoostedSN95]

Ill give this a bump, I just installed a NOS15685 adjustable cut off switch. I spliced it in to the chassis ground wire for the NMU. Very simple and seems effective-

anyone know what it should be set it? I have mine set to turn off the nitrous for everything except wide open throttle (fuel psi w/o vac line).

While doing this I noticed that when the circuit was open and I had the test light (12V from fuse block) on on the circuit (adjusting fuel pressure to close the circuit) the car actually throttled up. Once I adjusted the diaphragm and the light turned On (close circuit) the rpm came down back to normal.

Anyone know why this would happen?