Fuel pump relay up front,(speed relay)?

[Bob H]

Ok, I know the relay up front labeled Fuel Pump is for the speed portion of the circuit.  So if I want it to provide the full 12+V at idle and low cruising speeds - can I remove this?  In the end, I plan to put a relay in the back that bypasses all this and only uses the fuel pump voltage as a signal, not as power.  If I kill that circuit will it kill the overall power to the pump?  I don't think so, but needed to make sure.  My idea is at the end. 

 Let me see if I can find a diagram....

The circuit,(with the wire mod done to bypass the power going through the ignition switch), idling/cruising:




Speed circuit enabled, i.e. WOT and fast:



It seems to me by reading the schematic - that if the relay is missing or is open, then it goes to the resistor - which drops the voltage by ~3v.   So if I just butt connect the L/R to the W/R wire, it acts like full speed all the time?  I can't find the color legend - what are those two colors?  I assume something with red - just not sure what.  I'm going to assume they are the big gauge,(10), wires that are white and blue with red stripes.  That would make the most sense since its sending power to the fuel pump. 
Any thoughts? 
BTW, I didn't really want to get into that front harness - but with Samberg's radiator, there isn't much choice...  Its not that hard, but you do have to take your time. 

[Bob H]

I figured I'd put this here as well since I'm using this as my reference now.   Unless someone tells me I'm off my rocker, I'm butt connecting those two big wires from the FP relay. 
Here is my eventual plan:

[wickedrx7]

I have had this fuel pump relay grounded since I swapped my car, would connecting those two wire do the same thing? What size fuse are you going to put in?

[danzan]

1.  energize the fuel pump relay from the PCM.  could save your life.
2.  power the fuel pump from battery +.
3.  keep the fuel pump power wire as short as practical.  meaning, put the relay in the rear, near the pump.

[Speedfab]

Yes Bob, your thinking is correct.  We routinely remove that resistor from even modded rotary FD's - eliminates a potential point of failure.  Remove the resistor (it's located under the master cylinder/clutch master at the base of the firewall) and either make a jumper wire for the plug (I can send you one of these if you need it) or cut and splice the wires.  Once that is done, the pump speed relay is rendered unnecessary.
 
By all means though, do what Dan said as soon as you can: put a relay back near the pump and trigger it with the GM PCM and eliminate all the factory Mazda nonsense.

[danzan]

i have only one mazda component, in any circuit, which is required for running the drive train.  that one component is the ignition switch, which i can jumper.

i may lose the blower, or turn signal, or tail light, etc, but the f'n car will keep chuggin.

[93silverbullet]

Hi Bob,

If I remember correctly you're running an LS2 correct? If so, here's how I ran mine. Works perfectly.



BTW- I completely removed the Mazda wires and relay and ran my own with a 30AMP relay. Hope that helps you out.

[carl0s]

I followed Granny's instructions, which was to remove the front fuel pump high-speed relay, join the big wires there, and let the PCM's fuel-pump on signal go to the large EFI/Circuit Switch +ve relay on the shock tower (via the B1-01 in passenger footwell), after hard-wiring that relay's -ve to ground.
Seems like a nice way to do it to me ?
http://grannys.tripod.com/3LS18.html