Need help wiring up system, everything is wired correctly according to diagram from TNT but system still will not spray. Using MSD window switch but the only thing that has me wondering is we are not using a fuel pressure switch , we have the wire coming off the relay straight to the MSD window switch. Is this the problem or does anyone have any other thoughts?

 

that should be right

 

That is how it works. The msd switch sends a negative trigger so that should go to pin 85 on the relay. You need to have an arming switch with ignition switched 12 volt source going to your wot switch, and then to pin 86. Pin 30 goes to a fused power line from the battery. Pin 87 goes to your nitrous (and fuel) if your running a wet system. The other wire on the solenoid(s) go to ground.