Surge Tank Fuel Pump Wiring

[Zodiac]

So searching around mostly to get more confused. I have a 2006 wrx wiring harness and ECU. If I have the older pump (walbro 255lph) in the tank and now adding a external pump (another walbro 255lph) do I just tap off the two wires going to the original pump and use that? Or do I need to install another relay and if so what wires am I tapping into? Or do I have the external one run the way the original would have and have the lift pump always on through a relay?

[DodgyTim]

At 45 psi I think the Walbro draws about 8 or 9 amps.
You'd need to check fuse and wire ratings to run both pumps off the original circuit (and is there variable fuel pump controller on the US 2006?)
I'm using the factory circuit to run the surge tank pump (feed the injectors) and wired a new relay to provide power to the "in tank" pump.
Power for the relay comes of one of the unused fuses in the original fuse box


But, its all not tested yet....:(

[Bob_n_Cincy]

I'm curious how you guys are running the return hoses from the 2 pumps.
Can you explain.

I agree with Dodgytim's wiring.

Thanks
Bob

[DodgyTim]

My in tank pumps to the surge tank, which overflows back to the main tank
The surge pump feeds the fuel rail and the return goes to the surge tank as well
That way any fuel delivered to the surge tank stays ready for use, otherwise you have to scavenge the fuel from the main tank again

[Zodiac]

That sounds correct to me. On a 06 WRX Turbo model power goes to the relay which then goes to the fuel pump controller (which IS variable) which then in turn feeds the fuel pump. So basically wire the surge pump to feed the injectors from here. And so I should run the in tank pick up pump to go off a relay that goes off battery and ignition like in the picture below? Does this make the in tank pump to be always on as long as the car is running?


47021

[Zodiac]

As for surge tank plumbing DodgyTim has it down. Here's a quick pic also

47022

[Pearldrummer7]

I have a surge tank with a Walbro 255 in it (Radium generic FST with internal fuel pump). I wired it just like I wired my in tank pump- directly to 12V through a 20A switch on the dash board, and grounded locally. It's definitely louder than the stock pulse width modulator (the little silver fuel pump "brain"), but it seems to be just happy fuel wise.