rxcited2

Did you power the end of the wire going to the relay, or the other end? If you powered the other end, it would be like turning on your ignition, permanently! This could explain it.

Actually that ^^ doesn't make sense because then your pump would be always DEAD. One test you could perform is to yank the OEM fuel pump fuse. This is the one I pointed at in my marked up figure saying "REMOVE FUSE". If the modification is done correctly, then removing this fuse should be done anyway. However, if the pump goes off when you remove this, I don't know WTF is going on, but something is wrong.

HDP

iTrader: (2)

So the stock fuel pump fuse under the dash will no longer be used? So since the quick-disconnect connector on that fuse would fit perfect in the empty slot under the hood, could you just remove the connector under the dash and reuse it under the hood and not have to modify the empty slot?

Gadd

Hmm.. Never looked at it that close, it's worth a look but it's likely you'd have to do a lot of work to get it out. But it may be worth a trip to the junk yard to grab some Madza fuse boxes.

vtakk eg

so if you use the extra fuse holder, you cut the blue wire and spade it into the bottom, i got that but which end of the cut blue wire goes up in there?
the one coming from the circut relay, or the peice that is coming from the harness (where exactly do you do with the unused peice of wire

vtakk eg

and how do you hook it to the batt. terminal? a big crimp on ring , doesnt that provive constant power?, and where is the fuel pump fuse that you pull?

rxcited2

If I understand this correctly, the OEM fuel pump fuse is under the dash. This gives me an idea. Not sure how to do it yet, but if you could sever the positive supply from the ignition switch that powers the existing fuse, and replace this with unswitched positive from the battery, this would be exactly the same thing as Dale and Gadd's original modification. But it would use the existing fuel pump fuse so it would be very stock from an FD owner's perspective. See attatched figure.

Will this work and is there unswitched decent gaged positive available to the fuse box (under the dash?) where the OEM fuel pump fuse is located?

dubulup

Holy cow...I had no idea reading wire diagrams and modifing a single wire could be so hard, LOL.

step 1

If you don't pull the fuse you will be putting 12V live (HOT!) in a harness.

step 2

Now "good" 12V is applied to the relay

speed 1

This is the case while idling/cruising. The resistor dissapates ~3V, and supplies 9V to the pump

speed 2

Under boost, the "speed" relay is triggered by the ECU...since electricity flows like water (path of least resistance)...electrons find a new path thru the speed relay and your "new" 12V is now supplied to the pump.

Now, if this doesn't make sense...

rxcited2

Clear as daylight - thanks dubulup. What about my idea, do you think this would work and is there unswitched positive under the dash?

DamonB

I was wondering how the hell this thread ended up 6 pages long!

Guys, if you can't read or understand a schematic I don't recommend you working on your car's electrical system. This is not offered as a shot at you or your intelligence, it's advice that will prevent you from messing things up.

Eggie

Install a new run from battery to fuse to relay to pump. Connect the stock white/red wire to the new relay's trigger so that the factory wiring will switch the pump, but the actual power will travel only 3'.

Eggie

Oh - and a question. Dale, you didn't add another ground at the pump?

dubulup

theorically it will work and there is [there are two female spade connectors on top of the fuse block, on is unswitched and one is switched], but I don't know what AWG the wire is...

gadd has it right and is as clean as it gets.

damn, this is my 14 post in this thread and I don't even use the stock fuel pump circuit for my fuel pump

AHarada

iTrader: (25)

Ok found the problem, at 2am this morning. Thank god this isn't my DD.

It turns out when I pulled out the circuit opening relay (the green one) I bent the little metal keeper in the relay to always keep connection at the blue wire to the Blue w/ Red stripe wire, so the circuit wouldn't open and the fuel pump always recieved voltage.

So I bent the relay back, tested it with a battery, and it works great and I have voltage where I should, and continuity when and where I should.

Now the fuel pump doesn't turn on lol. I'm pretty sure it's because I never pulled the fuse out from under the dash. My car never came with a fuse box cover under the dash. Could someone post a pic of exactly which fuse I need to pull.

HDP

iTrader: (2)

Page Z1-4 in the FSM.

rxcited2

So you "accidentally" bent the contacts INSIDE the relay so it stayed closed even when no power was applied to the coil? (!!!) You're right, if you damaged the relay (so it was closed circuit all the time), then you wouldn't have had your fuel pump stuck on before all this, because the positive source to the relay would only be there when you turned on the ignition. With the modification in place, the relay has to be working properly or else your fuel pump would just stay on all the time, like you observed.

rxcited2

DamonB, this is now about optimizing this modification, not about making the thread longer.

Call me arrogant, but if we can make this modification while retaining the existing purpose and location of the fuel pump fuse (under the dash), I think THAT is cleaner. Why remove the OEM fuse, set up a NEW fuse (either in-line or in a spare opening in the engine bay fuse box), and run a new wire to the battery, if you can just sever one wire and make a jumper to unswitched positive in the under dash fuse box? The later seems cleaner to ME!

This all presumes there IS a suitably gaged positive unswitched source within or near the under dash fuse box... I got my FD back from the shop so I can look into it myself now. I'll see if I can replicate Dale's original experiement with a multimeter to check the before and after voltages with my idea...

DamonB

Because that defeats the entire purpose of the mod. This mod reduces voltage drop to the pump by eliminating connectors and small gauge wire between the battery and the pump.

Why do you think people have gone to the trouble to run new wires?

rxcited2

Dude ^^^, the problem with the stock wiring is NOT the wires, it is the fact that the pump power is going through the ignition switch. The modification I am suggesting will likely have exactly the same effect as either Dale or Gadd's methods. The only difference is theirs either adds a new inline fuse or uses a spare fuse in the fuse box containing the relay, whereas my mod continues to use the OEM FP fuse but cuts the ignition switch out of the circuit.

The only question I have about my idea is whether there is unswitched positive with sufficient current carrying capacity "handy" in the dash fuse box. If not and I had to run a new wire, then I would ditch my concept and use Gadd's. I'll let you guys know what I figure out.

Edit: ^^^ I guess dubulup answered this earlier when he stated there IS unswitched positive available in the under dash box. Usually a supply source to a fuse box is large gage. Also we already know the wire going from this box to the FP relay in the engine bay is BIG and BLUE. So I think my concept will work. Will try it out with before and after VM readings...and take some pics in case it pans out.

AHarada

iTrader: (25)

OK, I feel like I'm going in circles trying to figure out my problem and it's absolutely driving me crazy. Ever since I did this mod, my fuel pump will not turn on.

So here's what I've tested so far,

With the circuit opening relay out, the connector that the Blue L(F) wire connects to sees 12.xx volts. As does the B/LG wire. So I don't have any missing/blown fuses, and I have voltage up to where I should.

I tested the relay outside of the fusebox, and it works fine.


With the ignition ON,

If I ground out the L/B wire, then the relay closes and the fuel pump turns on. So this would obviously lead me to believe that I have a ground problem on the L/B wire. Now this is kind of weird, since I didn't even mess with this wire, and everything worked fine before I did this mod. So looking through diagrams and the FSM, it never even shows this wire going to ground. This wire would need to go to ground to close the relay and send voltage through the fuel pump. The diagrams above show that from the relay, the L/B wire goes straight to the data link connector. From there, it goes nowhere. So where does it get it's ground from?

What am I overlooking?

dubulup

that is my fault...(didn't have enough room for the entire diagram) do you see the DOT in the diagram on the L/B wire?

that runs to the ECU (1T). so, the ECU decides when to GND that relay powering the fuel pump.



here is another diagram (ignition)

AHarada

iTrader: (25)

You know what, I did see that dot and kinda wondered about it, but didn't think too much of it. Ok, so I'll check resistance from the relay and the data link connector to the PCM. I could have not even realized it and unplugged that wire or something. Hmm..is there any reason the PCM wouldn't ground the fuel pump relay?

As long as it isn't a problem with the ECU, do you think it's a problem to make my own ground? Does the ECU control the fuel pump for fuel cut or something?

Do you happen to know where that splice is on the wire and in the car?

rxcited2

So it looks like AHarada's ECU is not doing the right thing? Is that a stock ECU or a PFC? I guess you could check continuity beteen the 1T pin and ground with igntion on and off. Should be open when igntion off and closed with it on, right?

AHarada, I wasn't clear whether you had done the mod wrong and then corrected it, or it was right all along and then something happened. Originally you were saying your pump was ON all the time, now you are saying it is OFF all the time. Maybe you fried something in the ECU if you did it wrong the first time around?

DaleClark

iTrader: (55)

Nope, I didn't do anything with the fuel pump ground - every step I did is documented on the ClubRX writeup.

I think if you're not handy with electronics, my method is about as simple as it gets.

Dale

dubulup

maybe something inside the relay is now broken? Or the fuse blew...

if your car ran fine before...your ECU isn't the problem...or the wiring to it.

AHarada

iTrader: (25)

At first, I bent the relay to always be on, but I bent it back, tested the relay, and it works fine. The circuit closes when I put 12V and ground to the one side, and resistance on the other, and no resistance when it's open with no 12V or ground.