Fuel pump voltage booster schematic

[Sonic Blue 2V]

The Edelbrock N2O wiring diagram for the voltage booster unit (VBU) did not show relay labels and wasn't marked very well so I made a schematic. This is just a MSD Fuel Pump Booster they use to make their dry system work on a returnless fuel system.
The way it is supposed to work is when the nitrous is NOT activated, the ECM is in control of the fuel pump (varying the voltage to the pump to maintain 39psi at the fuel rail). When the nitrous is activated, the relays are thrown and the VBU is now driving the fuel pump at it's potentiometer adjustable voltage. As soon as you're off the nitrous, the relay swings back to it's normally closed position and the ECM takes over again. Please take a look and tell me if you see any flaws in the diagram, I'll be hooking it up this weekend :D

[Joe Lynch]

I think it is fine. You could substitute a single double pole double throw relay and simplify things a little. I was confused when looking at my own wiring diagrams as to which wire to the pump was the positive and which was the negative. I think you should check that before you wire it up. You probably have it right, but check it with a voltmeter before you break the wiring.

One other thing. The wires don't come from the PCM (computer), they come from the FPDM in the trunk and you have to wire up the VPU and relays in the trunk, not at the computer.

Joe Lynch

[Sonic Blue 2V]

I just took Edelbrock's wiring diagram and made a schematic from it as it was not labeled from their color coded relay sockets. I used the relay numbers to make it easy to reproduce without the relay sockets.
I will definely check the power to the pump to verify the polarity, good suggestion.
I decided to upgrade the fuel injectors before installing the VBU as I don't want to run lean due to stock fuel injectors. Hope to get them in this weekend.
Thanks again Joe!

[Joe Lynch]

Post up what you found out on the wiring. I have a Kenne Bell Boost-a-pump coming and want to know how yours worked out as well.

Joe