Just about to get wiring my dual 450s. It is converted to a RETURN setup. I ran 10 gauge from each pump up to the engine bay and am running two separate relays; one triggered off the stock pump relay trigger wire and the other from a hobbs switch.

It was a returnless system. I looked up the diagrams on all data and have tested the wire with my meter, Green/white stripe from PCM Green pin 9 to the fusebox, C2-A7.

The question is, being returnless, should the wire have 12v for a few seconds for priming or is staying on with the key normal? I'm getting 12v the whole time the key is on, it should work fine, just checking that it's normal and I for sure have the right wire. Dealing with the returnless stuff is foreign to me. I know normally a stock pump will prime for about 5-8 seconds.

 

i wired my single 450 up to a relay, 12v from battery to the relay then wire from harness turns it on

 

Which wire from the harness did you go to? I'm pretty confident on the one that I have.

 

This is from mangleds write-up from years ago. If you use this it will prime and run like stock.

 

i tapped into the actual plug that is on top of the fuel pump housing, i de pinned the stock fuel pump wires from it, and put them to my relay

 

In that picture above, that looks like it's labeled "Fuel Pump Supply Voltage" according to my Alldata diagrams. Now I think that is going to be power coming out of the relay going back to the stock fuel pump plug. That is Grey, pin F1. Wiring the new relay to that wire would just be using the stock relay to turn on another relay, wouldn't be necessary. Then you have two relays that could fail vs 1.

The important thing to remember on these pinout pictures is that they are showing the view on the fusebox side, not the back of it like in the picture above, so you have to look at it reversed.


The wire I tapped into is the signal wire out of the PCM DkGrn/Wht for the primary fuel pump relay trigger. This should be the wire that tells the relay to turn on, which is what it will be for me. A-7


Bottom view of fusebox.


Mine

 

Here it is, got it all wired today and it works perfect like stock. Checking with my meter a few days ago, my wire would read 12v the whole time the key is on. Now that I have the relay wired, it just turns the pump on for a few seconds and shuts off, so idk. It works though.

I was able to hide everything in the fuse box too. My two relays are right there in front and are covered by the lower fusebox cover. Tapped into 3 wires down there; fuel pump relay trigger for my main pump; ignition wire to go to my hobbs switch so if the hobbs ever gets stuck, the key will still shut it off rather than having a constant 12v supply; the ground for the relay coils.


Power for both pumps comes right off of the battery terminal there.