How do I wire in a hobbs switch for 2 fuel pumps?

[Clash0901]

Hi all,

I have done quite a bit of research on this subject and have multiple different answers. None of which apply specifically to the BRZ. I have the radium dual pump hanger and will be running 2 walbro 450's with a 2 prong 5psi Honeywell power switch. Please see questions below.

1) Do I run 2 relays, 1 for each pump, or do I run 1 relay for the secondary pump and run the primary off the stock wiring?

2) Can somebody draw a wiring diagram for me? *Can pay you if needed.*

I am just having a brain fart. I get how to wire the actual relay(s), but just need a full picture painted that's specific to the BRZ chassis and not the generic stuff i've seen online.

Thanks!

[Hags86]

So you are not using the Motec M150? What ECU are you using as that changes the answer to your question. This is for a 2JZ swap yeah?

[FRS Justin]

Here is what I suggest run a hot wire from the battery to the relays (2)fuse protected of course at the battery. then use you factory harness to trigger the relays. Simple and easy Ditch the hobbs switch or if you just have to have it put it on the ground circuit

[sid94]

Originally Posted by FRS Justin

Here is what I suggest run a hot wire from the battery to the relays (2)fuse protected of course at the battery. then use you factory harness to trigger the relays. Simple and easy Ditch the hobbs switch or if you just have to have it put it on the ground circuit

I agree with him ^^ when I wired up dual 485s for my friends s550 I used two fused wires directly from battery to two relays daisy chained to each other and used the power from pump module to trigger the dual relays and make it work like stock. More then likely if you’re doing this you should look into making it return style but keeping same fuel pump bucket to keep your fuel level gauge working




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[Hags86]

I'll draw you a diagram but need to know what engine/ECU combo. If you are using the OEM computer and the FA20 or a Motec with the 2J I'm have the data. Can't help if you are using the ECU that comes from the 2J.

I'd use the first pump with the Fuel Pump Controller so it spins slower at low revs and speeds up at higher revs. The second pump would then be binary (either full on.or full off) using either the Hobbs switch on the OEM computer or based on fuel demand if using the Motec.