Rotary Car Club - GTUs Turbo -HISGTUS-

I found this in one of my folders about car stuff...I don't remember where I got it from but if you remember then link to give props.

Quote:

Why rewire the fuel pump?
- Even on a car with a new alternator, new battery, new battery terminals, and
clean electrical connections (mine) I saw as low as 10v to the fuel pump with a
load on the system (lights on, stereo cranked, heater on, etc.)
- The fuel pump should, under boost, be seeing at LEAST 12v. Reduction in
voltage=reduction in fuel flow=bye-bye motor.

Considerations when rewiring the pump...
- First off, it should operate as normal. You turn on the key and go - no extra
switches, etc.
- The fuel pump resistor circuit should continue to work. This drops the fuel
pump voltage to 9v at idle and cruise to improve fuel economy.
- The safety switch in the air flow meter should continue to work. The airflow
meter, when closed, turns off the fuel pump. So, if you roll the car, you won't
be pumping gas out of the car at 30-40psi making a big fireball :).

OK, so how do you do it?

You'll need -
- a 12v automotive relay (Radio Shack)
- about 15 feet of 12 gauge wire
- an inline fuse for the 12 gauge wire
- about 20 feet of speaker wire (you need two wire runs to the back of the car,
and speaker wire has 2 wires)
- various crimp-on connectors (to connect to the relay and positive battery
terminal)
- electrical tape

OK, first off let's run the wire. The speaker wire needs to start at the airbox
location in the engine bay and end by the driver's side rear shock tower. The
12 gauge wire needs to come from the postive battery terminal to the same spot
(don't hook it up yet! :) Hook the inline fuse between the positive terminal
and the 12 gauge wire - you always want the fuse close to the battery. I used a
15 amp fuse, and it seems to be adequate.

Next, it's time to move the resistor and relay. Remove the airbox. There's a
metal bracket that has a relay and a aluminium box that looks like a heat sink.
It connects to the wiring harness with a large round white connector. Inside
the connector should look like so -

__--__
| - - - |
| - - - |
_______

Let's label these wires, as per the shop manual. Diagram below is on the
relay/resistor side:

__--__
|E C A |
|F D B |
_______

OK, cut the connector off the wiring harness. Leave enough slack on both sides
of the cut - we'll be re-splicing the connections in. Connect the speaker wire
to C and D.

So, now you've got your resistor and relay with a cut off connector. Move to
the back of the car. Remove the driver's side rear speaker assembly and the
plastic trim above where the jack goes. Pull the covering on the side of the
hatch area forward. On the side of the shock tower closest to the rear of the
car is a wiring harness with a white connector. This is the connection for the
fuel pump. There's 4 wires there - 2 for power and ground, and 2 for the fuel
level sender. On the fuel pump side of the wiring, the two topmost thicker
wires are power and ground. I believe power had a white stripe and ground is
just black. You might want to test it first and make sure you've got the right
wires. Cut both of them about 6 inches down from the connector - you might need
to cut off some of the covering around the wires. Time to hook up the relay.

Here's what you want to do - use the power lead that normally comes into the
fuel pump and the ground on the car side of the wiring harness to turn the relay
on and off. Run the 12 gauge wire from the battery terminal into the relay.

Time to wire up the resistor relay. Take the wires from terminals A and E and
splice them together. Take the wires from terminals B and F and splice them
together. Attach the speaker wire you ran from the front of the car to
terminals C and D. Run a wire from the relay (the opposite terminal that the 12
gauge wire is on) and attach that to terminals A and E that are spliced
together. Run a wire from the spliced terminals C and D to the fuel pump
positive lead. You can ground the fuel pump separately or just attach it to the
same ground wire it used in the past on the harness.

OK, go back to the front of the car. There should be 4 extra wires where you
cut the resistor relay off. Splice the wires that were on A and B together, and
the wires that were on E and F together. This lets the signal from the main
fuel pump relay travel back to the fuel pump area, and it activates the relay
there to bring the new 12 gauge wire online with the pump.

Time to test it. Get a jumper wire and jumper the fuel pump check connector -
it's a yellow two-prong connector on the passenger's side shock tower in the
engine bay. It might be buried a bit, so keep looking. After jumping the
connector, turn the key to "On" (don't start it) and go back to the hatch. You
should hear the fuel pump running. If not, check your wiring for good
connections.

Yes, this is a VERY complicated procedure, and you have to keep a lot of things
straight. If you have a shop manual, turn to pages 4B-70 and 4B-71 - there's a
really nice diagram of the whole setup there, along with a diagram of the fuel
pump resistor relay. This job took me just a Saturday afternoon. I haven't had
a chance to see what kind of voltage I'm getting yet, but I know it's got to be
better than before :).

The prinicpal of the idea is moving the fuel pump resistor relay near the back
and splicing a relay carrying a REAL voltage into the equation. This method
keeps all the factory safety features (air flow meter cutoff, check connector,
etc.) It also allows the resistor to function properly. When the relay for the
resistor is open, all the current goes through the resistor and is dropped to ~9
volts. When the relay closes, it makes a path with no resistance through that
part of the circuit, and we all know that electricity takes the path of least
resistance.

If any part of this is unclear, please let me know. It's a pretty complicated
procedure with a lot of wire-deciphering, and I think I got the gist of it down.
This procedure is VERY necessary with upgraded fuel pumps and fuel pressure
regulators as Bruce Lewis found out - the stock wiring just can't deliver enough
current. Hopefully this $10-20 mod will help save some modded engines out
there! :)