Relay Diagram

Hello everyone!

I'm fairly new here, I've watched all the club level videos and I feel pretty confident in taking on the wiring on my street car project. I do have questions and concerns however so feel free to chime in!

Its a K series Honda that'll be running 2 sets of injectors and 2 fuel pumps to get my desired power level. Stock coils.

In the solenoids circuit i have the ALT, Reverse Lockout, IAC, VTC, VTS, BCS, VSS, and flex fuel sensor.

I've attached a pic of the relay diagram and id like some insight so here are my questions.

1. Is the diagram correct or should i change anything?

2. Do I add a fuse to the power wire off the battery?

2. I'm not too sure on the fuse and wire sizing so any recommendations will be much appreciated!

Thanks!

Anyone?

Different people will have slightly different opinions -

I'd add a main circuit breaker (resetable fuse) between the battery and the main feeds, then use fused relays. With the secondary injector relay, I'd use two relays, one for each of the outputs you have.

You have a couple of 30A rated circuits, while some relays are "rated" for that, I have had failures, and I'd suggest using higher rated relays for those.

I might put the fuel pumps on a different 'main' relay, with a manual, spring loaded swithch, to prime the pumps, flush the lines, even drain the tank - but that's optional.

That said, if you're thinking of using the vehicle for any sort of motorsport, I'd suggest checking the regulations to see what they require, as that may require the wiring to be altered. Also, I'd upsize ALL the pump wiring from what you think they need - power is proportional to the square of the voltage, and any any excess voltage drops can have a BIG affect on the pumps' pressure-flow capabilities.

What pumps are you running?

Common turbine pumps i.e. "big" walbro are still going to be under 20 amps so I'm curious if you really need that 30 amp fuse or could be running less and mitigate Gord's concern. I agree with Gord, "30 amp" standard relays often don't hold up well in a race application when you get much over 20 amps.

It’s 2 Walbro 525LPH pumps

OK so sub 20 amps with proper wiring, voltage, which does relieve some of Gord's valid concern.

Yea ill be running 12awg wiring to/from the pumps and the wires are no longer than like 4ft. I could get away with a 20-25amp fuse but i decided to run 30 and a 30a relay. Ran it like that for over a year with zero issues.

Side note tho, I wasn't sure on the ecu fuse size so I contacted Fueltech and they told me i need to use a 30a fuse on the ecu circuit.

My next question is what size power wire do i run from the battery to all the relays and what size fuse should i use if i choose to install one?

25 or 30 amp fuse per pump circuit for those pumps, depending on how much margin you want to leave.