arghx

iTrader: (3)

Alright I did do a search and I've found a rather involved writeup at http://www.1300cc.com/howto/how2/rewire.htm .



So my question is this: on this makeshift wiring diagram, can I basically disregard all the stuff on the right side of the diagram because I have an N/A and thus no resistor?

So I'd be running a wire (with fuse) to the "power in" part of the relay. The "power out" part would go directly to the (regrounded) pump. The old fuel pump wires would trigger then relay? Doesn't seem too hard...

When I'm running the wire from the battery, I should run it through the firewall and under the carpet right?

iceblue

First things first. Take a multi meter and check the voltage at the fuel pump harness connector and the pump.

If you searched on this you should have come across a post I made about doing this exactly using a relay.

If the harness is receiving a full 12V then you only need to tap into the harness and if the pump is then you do not need to do anything. If you are not then yes you can rewire it.

The relay is a switching system if you do not wire it correctly it will be on all the time. You can un a constant power from the batt+ or from another strong source. But use the + wire from the fuel pump harness to trigger the relay. Then go-ahead and run a power out to the pump and ground everything. If you run from the firewall no real need there is pleany of other strong places to tap into then yes use a grommet fuse it and run it under the carpet just like the factor harness is.

NZConvertible

Actually if we're talking "first things first", we should first point out that S4 NA's don't have the 2-speed pump system, so the write-up referred to is useless. There is no resistor/relay to rewire or relocate.

To do this on S4 NA, all you do is run a new fused power wire from the battery directly to the fuel pump via a normal 30A relay, and switch the relay with the original fuel pump wiring. Very simple and easy.

arghx

iTrader: (3)

So that's a yes then? I'm trying to get what I can out of the writeup. I know I don't have to relocate anything.

NZConvertible

Pretty much yes, but the layout of the relay pins looks nothing like that so you can't really use it. Try this:

1. [*]
2. [*]
3. [*]
4. [*]

iceblue

I thought that's what I said

SonicRaT

iTrader: (6)

I really should redo most of those write-ups, lol.

NZConvertible

Yeah but I said it so he could understand it...

iceblue

;-) where would we be without thoughs that can desipher my encryption.

Hey atleast I tryd :-D

arghx

iTrader: (3)

Thanks for the help guys. I'm gonna check the voltage tomorrow... I'm kind hoping that this is the source of my lean condition, because otherwise I may need a fuel pressure regulator or something. I have an FD fuel pump and 550 secondaries and it's still running lean...

arghx

iTrader: (3)

The voltage read 12.5 . Looks like that's not the problem. Maybe I need a fuel pressure regulator or something.

NZConvertible

You need to measure the voltage at the fuel pump with the engine running. Should be ~14V

arghx

iTrader: (3)

I measured it at the white connector near the speaker with the four wires. It was at 12.5v with the car idling. I can double check everything tomorrow I guess. I don't even get 14V to my whole electrical system, at least according to the stock gauge--damn s4 alternator. I should double check that too.

Assuming it's correct, Is 12.5V low enough to cause a lean condition? I don't want to rewire the pump if it's not going to accomplish anything.

matts86fc3s

12 volts should be sufficient tho right? i mean it is a 12 volt system... im reading a little bit over 12 volts throught my entire electrical system and the guage on my dash

NZConvertible

12V is battery voltage. When the engine's running the alternator should be keeping the system voltage above 14V. If it's not, the alternator needs to be fixed or else a dead battery is in your near future. The "damn S4 alternator" is perfectly capable of producing the correct voltage unless something is broken. Don't bother with fuel pump wiring until it's sorted.

HAILERS

Sorry, but the wire color on the Rear Harness side of the fuel pump plug is BLUE and on the fuel pump side of the plug it is BLACK with a WHITE stripe.

arghx

iTrader: (3)

I used a multimeter to check system voltage today. The stock gauge is obviously inaccurate--I'm a little above 14 volts.

driftin8ez

sorry to bring back an old post. Just wanted to make sure that this little write up applies to an S5 N/A aswell.

NZConvertible

No, S5 NA's use the same 2-speed fuel pump system as S4 and S5 Turbos. You need to use the write-up mentioned earlier.

http://www.1300cc.com/howto/how2/rewire.htm

driftin8ez

what was the advantage of using the 2 speed fuel pump system?

rogrx7

iTrader: (11)

what if you have a n/a shell and a turbo motor. how do you rewire it? How do u get the 2 speed jive.

arghx

iTrader: (3)

sounds like you don't even need the two speed thing, it's just to save a little bit of gas mileage

wishIhadanFC

Is this really even necessary for n/a cars?

NZConvertible

The 2-speed pump system is mainly there to extend pump life by only pushing it hard when necessary. The FSM says it's "provided to assure good pump operation". It's controlled by the ECU and it's a safe assumption that the system's effect is compensated for by the fuel maps (low speed = lower pressure = less fuel flow). If you disable it and feed full battery voltage to the pump all the time, all you'll do is run richer at low load. This is just an unnecessary waste of gas for zero gain. There's no sensible reason to disable it, whether Turbo or NA.

If you're putting a Turbo motor into an S4 NA and using the Turbo ECU then you need to add the relay/resistor and wiring. You can see what you need to add by comparing the Turbo and NA fuel pump wiring diagrams (FSM pages 50-34 and 50-36). It's pretty simple.

If you're putting a Turbo motor into an S4 NA and keeping the NA ECU then you don't need the relay/resistor. If you're putting a Turbo motor into an S5 NA then you already have it.