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Fuel Pressure Safety Switch with Zex Wet Kit

  • Thread starter Thread starter ukgtguy
  • Start date Start date Jun 10, 2009
U

ukgtguy

New Member
Apr 1, 2005
13
0
1
North-East England
Jun 10, 2009
#1
  • Jun 10, 2009
  • #1
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
 
B

BoostedSN95

Founding Member
Jun 29, 2000
123
0
0
cc,tx
Aug 16, 2010
#2
  • Aug 16, 2010
  • #2
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?
 
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