Radium Pressure Switch Setup
Overview
For 2-pump fuel pump hardwire kits with the Radium hanger, the pressure switch is designed to trigger the secondary pump after a predetermined boost pressure. Having the secondary pump running in low or no boost situations is not ideal because it will overrun most fuel pressure regulators.
The Radium Pressure Switch for your secondary fuel pump is designed to run on manifold pressure.
DO NOT TIE THIS TO FUEL PRESSURE
Please consult your tuner for the recommended pressure setting for your application. The switch ranges from 3 to 15 PSI.
Insert the terminals into the plug (as shown) with the crimped side facing the same direction as the plug locking tab. Push the terminal in until it clicks into place.
With both wires pushed into the plug, lock them in place by pushing the red retaining clip into the closed position.
With the wiring complete, the next step is to adjust the set point.
Connect a continuity tester (such as a multimeter) to the two wires of the pressure switch. Attach a hand pump, such as a "Mighty Vac" that has a positive pressure mode, with a gauge to the port of the pressure switch. Increase the pressure and watch the gauge for when the switch triggers.
The switch can be adjusted by removing the electrical connector and inserting a 3MM Allen key. Tightening the screw increases the set point, and loosening the screw decreases it. The available adjustability is between 3 and 15psi.
Install the pressure switch into a threaded 1/8NPT hole in the intake manifold. If a threaded 1/8NPT hole does not exist, one will have to be created by drilling and tapping. Alternatively, a brass female 1/8NPT to hose barb adapter can be installed on the switch (seen in the picture), along with a vacuum hose connected to an existing vacuum port on the intake manifold. Make sure to use a small amount of PTFE tape or paste on the threads.
The video above gives an idea of how to connect up the pressure switch to the manifold if you want to just tie into a standard manifold pressure line.