Yes on adjustable. I think the range is 7-15 psi. I imagine that the adjustment is done via a setscrew.

 

Yes you can loosen or tighten the small set screw in the switch. I used a MityVac to pressurize the port so I could set the switch to 13psi.

 

Im confused about how the hobbs switch works. How does it know what pressure you're getting in order to activate the high volt setting? I see there is a vac/press port on the hobbs switch but I didn't see anyone mention hooking it up to a boost source in this thread, so is it not used?

 

Yes there is a pressure port on the switch that once pressurized, will activate the switch, completing the circuit.

 

I'll add that the pressure switch is not meant to be a power relay. It only serves to complete the circuit on the control side of a power relay as shown in Biggiesacks diagram.

 

I'm actually running mine as a relay with an line fuse off the battery. I couldnt really think of any downsides to running it this way. If the switch failed, it would be stuck on continuous "on" until I disconnected the power wire from the switch or continuous "off" and would run the pump off factory wiring as it was before I ran the 10ga wire inline with the OEM wiring. If it got too hot, it would pop the fuse. I will setup an AFR failsafe and a Fuel Pressure failsafe through my Haltech just in case though..

 

a hobbs switch isn't meant to move current like a relay is, so it will be a bottle neck at best. Specifically the spoolinup one lists its current rating at 15amps, which isn't even good enough for a factory pump.

 

Interesting.. I may need to revisit that..

 

You should.

 

I'll be installing a 450 pretty soon on my evo and I think I'm going to try and make a 3 stage voltage system for it. I'll add a resistor to the factory high stage to make it into a medium and then use the hobbs switch for the new high. I think I'll shoot for 20psi activation on the hobbs switch. If it works out I'll post some stuff about how I implemented it.

I figured this is already happening as a byproduct of triggering off of a hobbs switch, and that the factory high stage can only deliver so many amps to the pump. I am going to try and just be more deliberate with how many amps are delivered to the pump during that "middle" stage.

 

There needs to be an ELI5 for those of us (me) that are not elecrically inclined. Like seriously Dr. Seuss style.

 

I kind of just had this idea when I was thinking about how I want to go about installing this new pump. I'll post way more details as I get further down the rabbit hole. I mostly wanted to throw this idea out there to see if anyone thought I was off my rocker. I'm still researching my parts order and I have to logistically figure out where the best place to even put the new resistor is going to be. Before that even I need to figure out the physical dimensions of the resistor, which means I need to settle on a part, which means I need to figure out what resistance I want to try.....and it pretty much keeps going down the rabbit hole like this lol. I am kind of half way between the conceptual stage and the planning.

 

Gotcha. I try reading through this stuff and it's WAY over my head. I'm still lost with the normal high/low rewire. I can tear down an engine and reassemble with no problem, but ask me to wire some **** and it's a wrap lol. Really just need to find someone local to walk me through while I'm doing it.

 

The 450 doesn't flow enough to need three stages. You can just raise the factory crossover point if you really wanted to, the the 525 pump need that in my car. I think we bumped it to like 130 load, which I can't remember what is for boost off the top of my head

 

Oh yah totally, I know people have been installing these things for a long time and making it work. I even purchased a radium jet pump to replace the factory one, so I'm sure i especially wouldn't need to do this. I just enjoy tinkering with stuff. Since I'm already doing this I figured I would give it a shot and see how it turned out. It's a simple enough thing to do (I think) that even very minimal gains in efficiency might make it worth it (to me anyway).