R33 Fuel Pump - Stock Setup

[MBS206]

Alrighty guys and girls.

Putting an ECU into my car, and have come across a problem whilst tuning.

At 5000RPM, 10.5PSi, my AFR (On a wideband 02) is going to the maximum richness of 13:1 (WOAH, thats bad!)

Now, car is running stock fuel pump, stock fuel reg, stock injectors.

Fuel pump is wired up using the fuel pump relay pin on the stock wiring loom, but from what I can gather, there is another circuit in there also, that enables the fuel pump to enter a faster running state. Now, from what I can see from wiring diagrams, this is something like pin 106, but the issue is, I would like to know how the stock ECU operates this.

Does it:

a) Provide 12Volts when the higher state is required?

b) Ground out the wire, when the higher state is required?

I know that this can be tested, but I can't get to the car right now, and won't be able to for a little while, and was just wanting some knowledge on how this setup operates.

Also: At the moment, I would prefer to NOT be going to do the fuel pump direct feed mod that is written in the FAQ section. So please, don't mention it.

And don't mention, "get a bigger pump" etc as this isn't the pump, or fuel systems limit.

The stock ECU, at the same boost pressure sees AFRs around 10.5:1 - 11:1 so it seems to be that the whole fuelling side of the car, I'm not quite understanding (Electrically on the fuel pump itself)

Any help on how this system works?

[R31Nismoid]

You know why its going rich ye?

Its the stock ECU bogging you down.

Thats the question (if im right), in that your wondering why it goes rich all of a sudden?

[MBS206]

No sorry, I'm trying to work out how to adjust my aftermarket ECUs wiring, to enable me to get an AFR richer then 13:1 when the injectors are at 100% duty cycle.

[sweetr33]

just put an 040 into it n dont worry bout tampering with wires, probably open up a can of worms.

[MBS206]

Okay guys, I've been PM'd the info that I needed, and for those in the future who want this info.

The fuel pump runs at dual stage, just connect the fuel pump relay wire will give you low speed.

From the info I was sent, grounding pin 104 sends the pump into high speed mode, delivering more fuel.

Will let you know on Saturday night how I go.

This can be locked now if the mods want.

Matt