HobbeZ

I've been searching the previous post and i can't seem to find the diagram / instructions on how to upgrade the wiring for the fuel pump? does anyone still have it or directions on how to do so? thank yo

dubulup

search the single turbo forum

HobbeZ

yah searched the forum but the one in the single turbo section refers back to a thread posted here.. it doesn't have the wiring diagram in it anymore. That's the main thing i am looking for

TwinTriangles

Ooh I've been looking for that too.

M104-AMG

iTrader: (8)

In principle what you are doing is basically "relaying" the fuel-pump, just like people do with headlights.

That is, the existing fuel-pump power-lines (12VDC) will activate/control a heavy-duty 12VDC 20+ amp relay (use Hella over a generic) and you run NEW dedicated 10-gauge or better power-lines (each FUSED) running DIRECTLY from the battery-posts to the fuel-pump.

Although the diagram is for headlamps, the same concepts apply (you just don't have a HIGH/LOW-beam switch) and headlights.

In short, on the relay:

terminal 86 to the existing fuel-pump positive wire;
terminal 85 to the existing fuel-pump negative wire (preferred, though to ground may work);
terminal 30 NEW 10-gauge wire FUSED to battery-post positive OR alternator B+ ;
terminal 87 NEW 10-gauge wire to fuel-pump POSITIVE terminal;

While you may keep the existing fuel-pump NEGATIVE wire to ground, I would run a NEW 10-gauge FUSED wire back to the battery post negative.

Things are easier when pulling 10-gauge ZIP cord.

You can get a Hella relay kit from him here for about $35 (RIK-1):

http://www.danielsternlighting.com/p.../products.html


:-) neil

PS: do this to your stock lights, and you will see a dramatic result.

Taken from:
http://www.danielsternlighting.com/t...ys/relays.html

HobbeZ

any particular type of fuse that needs to be used?

M104-AMG

iTrader: (8)

Any type of automotive fuse rated for the PEAK amperage/current you expect to be drawing and no greater than the load of the relay used (usually between 15 and 20 amps).

:-) neil

alberto_mg

I think this is what you are looking for: https://www.rx7club.com/showthread.p...el+pump+wiring

Good thread for an archive...

HobbeZ

yup that's the thread i was refering too, but it doesn't have the diagram he mentions anywhere in that post.. i guess it was taken down or something. but M104-AMG, explained it out very well thank you.

2MCHPWR

iTrader: (2)

i just did this last night. before i did the rewire job, i was seeing 10.9 under load. but after rewiring, its 14.1 i got 10 gauge wire with some gold plated connectors at autozone, including a $3.99 relay and i'm golden tonight i check my fuel pressure to make sure its higher than before. another relay diagram:
http://www.ado13.com/techs/relay.htm

M104-AMG

iTrader: (8)

Nice relay schematic!

Just a warning on the cheap $3.99 "McParts" relays.

I have had many fail in less than 3-months doing 20-amp duty on a SPAL puller-fan.

I went to a diesel alternator/starter rebuilder and purchased a $9 Hella relay and it has been working fine for the last two years.

I would HATE to have a fuel-pump on a FD fail, so IMHO, get a Hella or other well known brand designed for automotive/marine use (e.g., vibration & corrosion resistant).

:-) neil

PS: here's that new schematic that 2MCHPWR linked:

HobbeZ

another question... how did you end up powering the fuel pump? Did you end up splicing into the original connector? or did you run the 10 gauge wire directly to the fuel pump? I am trying to keep the tank as isolated as possible and it seems if i ran the 10 gauge wire to the fuel pump directly i'd end up having a small problem with lke sealing the tank completely shut. If you did utilize the factory harness which wires are the +, -/ ground?

HobbeZ

dam i hate to answer my own question but here is a thread if anyone searches on what kinda needs to be done
https://www.rx7club.com/showthread.p...el+pump+wiring
from my take of the whole wiring etc it seems like you will need to run that 10 gauge wire into the fuel tank and directly to the fuel pump. To do so you'll need to drill holes in the fuel tank cover and seal them with some kind of fuel resistance sealant. (anyone have any suggestions for this?)
I went to radio shack and picked up a 12VDC 30 a relay <-- is this adequate?
so I assume i just need to wire it up according to the outline listed above. I also need to drill the fuel tank cover and run the 10 gauge wire DIRECTLY to the fuel pump.

I am trying to create a sorta easy how-to for the people who arn't exp too well versed in wiring etc

HobbeZ

I found the original text for the rewriting. It is different from the method explained above

It has been known for a long time that the stock Mazda FD fuel pump wiring does not
allow full voltage to reach the pump even after the FP resistor has been bypassed by
the relay. Many have totally rewired their FP by running full voltage directly from
the battery all the time. This works great except the FP runs full voltage even when
not needed. I decided to analyze and mod it for the easiest fix. This will help any
pump running the stock wiring to perform better.

Following is the results for my March 1992 RX-7 R1.

At idle with the FP resistor manually bypassed, the voltage at the battery was 14.2VDC.
Across the FP (+ wire to ground wire at the FP connector), it read 11.8VDC. That is a
2.4 volts loss, or 16.9%.

First I grounded the ground wire at the FP directly to the trunk floor. This had an
immediate result as the voltage across the pump went up by .4volts to 12.2VDC. That
is a 3.4% increase.

Next I ran a secondary + wire from the FP to the FP speed control relay. It was
initially disappointing as it made no difference at all. Later it did.

Looking at the wiring diagram for our car, The injectors (and some other functions)
get their power directly from the + side of the battery. The EGI relay which is
controlled by the ignition switch makes that connection. The ignition switch also
switches on the FP relay to allow power to the FP. But the FP gets it's power through
the ignition switch, not directly from the battery. This is where the major voltage
loss is.

I bought a 20amp-12VDC blade fuse holder from NAPA and some spare 20amp fuses. I cut
the BLUE solid + side wire between the FP relay and it's normal 20amp fuse which goes
to the ignition switch. I did this under the relay/fuse box on the driver's side fender.
I ran a heavy gage wire from the relay side of the cut through the new 20amp fuse to
the + side of the battery.

Retesting the idle voltage at the pump, it now was 13.5VDC. That is a 14.4% increase
in voltage to the pump over stock. Or a loss of only 4.9% as compared to 16.9% originally.
Remember the second wire which did not make any difference above. Well when I now
disconnected it, the FP voltage dropped by .4VDC to 13.1VDC, so it ends up helping after all.

What does all this mean. My pump will now be able to run closer to it's advertised potential
and pump more fuel at high boost levels. This will reduce the injector duty cycle.

2MCHPWR

iTrader: (2)

hobbez, mine is making 14.1 now and fuel pressure is perfect for my LS1 application at 56psi and is no longer falling off under WOT in high RPM's. i did not do what you mentioned about drilling into tank and new wires directly to pump. i just left about 8 inches of the original pos and neg wires to the pump and connected them to 10 gauge for a few more inches before connecting to the relay. the stock old wires to the pump are fine since i'm only using them for less than a foot. if you want a pic, let me know. don't kill yourself with this; i'm a complete newbie and it took under 1 hour to rewire whole thing. i just bought a lot of those crimpy connectors (gold plate spade to slip on relay pins, hoops to ground to body and bigger hoop to hook up to battery).