Fuel Pump Direct Feed Rewire.

[tacker]

Cubes,

If what you say is correct i will need to look into this quickly.

Just one question though, as you mention i didnt know that the normal trigger for the pump could shut down if the car stalled or such. Good to know really.

[HKS-R33]

hey guys, i spoke to my tuner today and he said all that i have to do is splice into the earth for the fuel pump and put it to a direct earth and it will up the voltage. Will this actually work?

Thanks, Mike.

[Cubes]

I tested that.. Using the chassis as an earth it raised voltage 0.5v over the std 11.2v

I think your tuner is thinking we are discussing the high/low voltage.

[justin911]

i didnt understand a fair bit of this thread... but it seems you only need to do this if you have 2 x fuel pumps right ???

I've just got a single 040... do i need to worry bout this ??

[Cubes]

I wouldn't bother unless you run out of fuel.

I had issues, I measured fuel pump voltage, rewired and saw the car instantly run richer at wot.

[SLVR32GTR]

Hi Guys,

This has been a really interesting read! I was hoping that you guys could clear up a few grey areas that i still have tho.

I am going to be running a bosch 040 or 044 pump inside my tank on my 32 GTR soon as i am upgrading the turbos and what not. My power aim will be around 320awkw and im wondering if this mod is required (as i know the pumps run approx. 230l/hr and 330l/hr respectively at 13.8v)?

Where abouts is the factory voltage control module located in the car?? Is it possible to rewire the pump but still use the factory voltage control module, as to only supply the pump with a lower voltage at idle but still have the 13.8v at higher rpm?? If not, im guessing the Jaycar kit that Sydneykid was talking about will be needed.

Thanks in advance for clearing it up for me.

Tony

[Cubes]

I'm not sure about the other PFC's but when I dropped the PFC in to my R32 it constantly supplied the pump with high voltage. No more low voltage on idle with the PFC, In mine and other R32 GTST's I've seen.

I believe it would be possible to rewire the pump to still use the factory voltage control module. From memory I remember seeing something in the manual about the resistor pack to drop the fuel pumps voltage is located in the engine bay.

If its needed in your case.... suck and see... Unless you want to do it just to be safe and possibly save you having to go back for another tune, but chances are with a decent 044 even at the lowever voltage it will be fine. But really.. I don't know as there's a few variables that man influence if its up to the task, fuel pressure, boost and injectors size. Run less fuel pressure and the fuel pump will flow more.

[R31Nismoid]

added to FI guide...

i damn well knew there was a thread on fuel wiring for the full volts

I thought it was in DIY though hehehe

[Craved]

anyone know what kind of current is drawn from the std fuel pump, same with the bosche 044 pumps?

with both of these running from direct power via a switched relay (each) finding its drawing alot of current making the car take longer to start

as in if i prime the system and turn the pumps off, then the car starts easier, then i switch the pumps on.

this is ona 550CA 60amp hour battery

[tacker]

Where is your battery located ??

[Craved]

in the boot, but not in the STD location that R33's have ..

[AzzurrA]

*subscribes*

[tacker]

sorry about the late reply,

I would look at doing the oposite in your case and run larger cables to the starter motor. One thing that could be an issue is if your cables can not carry the current to run the starter motor, then the cable get hot during your start up, resistance of the cable goes up voltage goes down, then current goes up again! A very nasty circle.

Also a dircet cable from the negitive terminal to the engine block might help as well, if you dont have that already.

[Craved]

hmm its more ECU related than started motor ...

the dash lights go out when cranking then comeback on then the car starts

turning off the pumps just reduce the time the lights turn off for..

strange issue and i havent had time to play around with the currents that are being drawn when doing the above.

[tacker]

Strange,

does the starter motor sound like its struggling to turn the motor over. Do your self a favor if you have a multi meter connect it across the battery terminals and record what your minimum voltage was during the time your starter motor was turning over.

[AzzurrA]

you've checked the charge in your battery?

[Craved]

yeah will have a look, but no the starter turns the car over fine, just a momentary drop of power to the PFC

this is reduced further when jump starting the car..

can even get that bad if the battery is low that the car turns over but the lights never come on and it wont start ..

one day i'll find it

[Cubes]

Have you had the motor out and rebuilt at any time?

May just be a bad earth.

[Craved]

Have you had the motor out and rebuilt at any time?

May just be a bad earth.

motor hasn't been out, only ever head off..

have been looking into making my own earth kit for it all.... just a matter of free time which i dont have much of

only earth i know to be missing is the one the the turbo manifold.. which has been gone for years

[tacker]

Not something like a bad ACC relay?