R34 GT N/A Fuel Pump Wiring

[Toff]

Hi guys,  Tried bumping an old thread on this subject a few days ago but no joy. Anyway, I have an ENR34 And i was intending on doing the GTT "Hard Wire" mod to get constant voltage on my fuel pump. However after a quick search i found that this is possibly not needed?

The thread had one comment stating that they had the same plugs etc but no relay to adjust the voltage. Would this mean it recieves a constant voltage closer to 15v say, Or is it a lot lower? 

https://www.sau.com.au/forums/topic/291561-r34-turbo-fuel-system-on-na-same-wiring-harness/

Have i got it back to front?

 

Thanks!

[GTSBoy]

Why don't you put a multimeter onto it and find out for yourself?

[Kinkstaah]

Also if the car is N/A I would wager the N/A pump could live with the N/A Wiring.

This was really more of a mod for aftermarket pumps that really wanted (needed) a direct 14v.

[iruvyouskyrine]

NA engine will never need enough fuel to outflow the standard NA fuel setup.

[Toff]

@GTSBoy Ahhhh the infamous GTSBoy smartass, super helpful comment, I love reading these when i browse the site. In response to that i am away with work so an ask on a forum is the next best thing isnt it? Because then i get helpful people like yourself answering for me.

And @iruvyouskyrine @Kinkstaah I should have added, I swapped in a forged NEO with Borgwarner S362 and Link G4+ Fury etc etc etc so its no longer N/A. Swapped hubs etc also. So i need a constant supply. 

Last option is pull it all and rewire the lot but i dont think i require it. Walbro 460LPH And Bosch EV14 850CC Injectors

 

Thanks for your help

 

[GTSBoy]

Well, in that case, why don't you download the service manual and check out the wiring diagram, seeing as you're working on your car by remote?

[Toff]

@GTSBoy I had a look at page 19 of the workshop manual  but not 100% on what i am looking at tbh! It clarified that the fuel pump control module and dropping resistor are not included on the DE motors, but as far as what voltage is actually supplied im still not sure. Could you tell me what voltage is received? As far as i can work out the lines that run back to the ECU plug are voltage supplied, so im guessing its just 14v or whatever is sent to the plug? Or am i way off the mark? Battery supplies plug with 14v or whatever and everything off that plug that takes a feed regulates itself with resistors and voltage droppers etc?

 

Thanks

Edited February 15, 2019 by Toff

[GTSBoy]

If the power is "controlled" by the ECU then it is very unlikely to be anything other than battery voltage.  There is no sense in dropping resistors etc inside an ECU.  That would just generate waste heat, which is the enemy of electronics.  It's the reason why the FPCM on the turbos is a separate module.

The only thing likely to be in the ECU would be a MOSFET to switch the power down to earth.  (ie, it is unlikely that the ECU is the source of 12V for the pump.  Instead, it is most likely that the power comes from the battery (through a fuse), through the pump and switched to earth at the ECU).

If you have the diagram, post it up.  I don't think I would have the R34 NA diagrams around here, unless they are hiding in the GTT manual.

[GTSBoy]

Turns out the DE wiring diagram is the same as the DET wiring diagram with DET specific parts labelled.  On the pasted image, ignore the bits I put the red box around.  They are DET specific (basically the FPCM and the dropping resistor that makes it work).

You have fused power coming in from the left, through the fuel pump relay.  The switched side of the relay runs through the fuel pump to earth, and the coil side of the relay runs to the ECU's pin that activates the relay.  That's it.  It's effectively direct wired....just probably with thin wire.

Edited February 16, 2019 by GTSBoy

[Toff]

@GTSBoy That's the diagram I was looking at, I was on the right track then! Thanks for your help, much appreciated. We got there in the end!

Hopefully be useful to others in the future.

 

Thanks

Toff

[R32boz]

@Toff was just wondering if you ended up rewiring it? Would the thicker wire help much or is it ok to leave the current setup with the stock thin direct wire.